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STATE OF FLORIDA
STATE BOARD OF CONSERVATION

DIVISION OF GEOLOGY


FLORIDA GEOLOGICAL SURVEY
Robert O. Vernon, Director




REPORT OF INVESTIGATIONS NO. 40





WATER RESOURCES

OF

ESCAMBIA AND SANTA ROSA

COUNTIES, FLORIDA


By
Rufus H. Musgrove, Jack T. Barraclough, and
Rodney G. Grantham


Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
FLORIDA GEOLOGICAL SURVEY,
ESCAMBIA COUNTY, SANTA ROSA COUNTY,
and the
CITY OF PENSACOLA


Tallahassee
1965







vl 4o
AGRI-
CULTURAL
LIBRARY
FLORIDA STATE BOARD

OF

CONSERVATION


HAYDON BURNS
Governor


TOM ADAMS
Secretary of State




BROWARD WILLIAMS
Treasurer




THOMAS D. BAILEY
Superintendent of Public Instruction


EARL FAIRCLOTH
Attorney General




RAY E. GREEN
Comptroller




DOYLE CONNER
Commissioner of Agriculture


W. RANDOLPH HODGES
Director






LETTER OF TRANSMITTAL


{r^ tJt ^7eoiyoacai s irveyf

TALLAHASSEE

January 28, 1965

Governor Haydon Burns, Chairman
State Board of Conservation
Tallahassee, Florida

Dear Governor Burns:

The Florida Geological Survey is publishing the "Water Resources of
Escambia and Santa Rosa Counties, Florida," as its Report of Investiga-
tions No. 40. This report was prepared from a cooperative program be-
tween the U. S. Geological Survey, the Florida Geological Survey,
Escambia County, Santa Rosa County, and the City of Pensacola.
As you know, Escambia and Santa Rosa counties are the westernmost
counties in Florida. Much of the recent industrial growth of this section
of Florida has been placed in this area. The impact and demand for
water resources have been greatly accelerated, and this study was un-
dertaken by this department, the counties, and the City of Pensacola,
through the cooperative program to monitor the salt-water-fresh-water
contact, to determine the total demand for water at the moment, and to
try to meet the future needs of the area. I believe that the details pre-
sented in the report will meet the intended purpose.

Respectfully yours,
Robert O. Vernon
Director and State Geologist



























Completed manuscript received
November 30, 1964
Published for the Florida Geological Survey
By Rose Printing Company
Tallahassee
1965







PREFACE


This report is the result of a 4-year investigation dealing with the
water resources of Escambia and Santa Rosa counties, Florida. The mild
climate and excellent water supplies are prime reasons for industrial de-
velopment in this section of Florida. Information on the water resources
of the area prior to this investigation was sketchy and based on a
minimum of documented data. The purpose of this project was to collect
water data to combine with data previously collected into an interpreta-
tive report that will be beneficial to water users.
In 1958, the U.S. Geological Survey in cooperation with the Florida
Geological Survey began a detailed investigation of the surface-water
and ground-water resources of Escambia and Santa Rosa counties, Flor-
ida. The investigation was financed by the U.S. Geological Survey, the
Florida Geological Survey, Escambia and Santa Rosa counties, and the
city of Pensacola.
The investigation was made by the following personnel of the Water
Resources Division of the U.S. Geological Survey: Rufus H. Musgrove,
hydraulic engineer, Surface Water Branch; Jack T. Barraclough, hydrau-
lic engineer, Ground Water Branch; and Rodney G. Grantham, chemist,
Quality of Water Branch. Owen T. Marsh, geologist, Ground Water
Branch, did the basic geologic study and was transferred before the
completion of the investigation. The work was supervised by A. O.
Patterson, district engineer, Surface Water Branch; M. I. Rorabaugh,
succeeded by C. S. Conover, district engineers, Ground Water Branch;
and J. W. Guerin, district chemist, succeeded by K. A. Mac Kichan,
district engineer, Quality of Water Branch.
Appreciation is expressed to the many individuals who furnished in-
formation and in particular to the following persons for providing infor-
mation and extending courtesies which greatly facilitated the investiga-
tion:

M. E. Batz, B. T. Dean, C. P. Neiswender, and C. A. Witcher, Jr.-
The Chemstrand Corporation
D. W. Young, C. E. Adams, and J. A. Hamm, Jr.-St. Regis Paper
Company
E. L. Russell, W. E. Moore, H. E. Province, Duncan Goldthwaite,
J. F. Schindler, and J. S. Porter-The California Company
R. C. Howard and M. F. Kirby-Gulf Oil Corporation
Stanley Sweeney and J. P. Bowers-Water Department, city of
Pensacola





PREFACE


J. J. Pinke-American Cyanamid Company
J. J. Petruska-Newport Industries Division
A. G. Symons-Layne-Central Company
C. G. Mauriello and Robert Schneider-Bureau of Sanitary Engineer-
ing, Florida State Board of Health
Lehmon Spillers-Spillers Well and Pump Company
D. M. Harvey-Harvey Hardware and Mill Supply








CONTENTS

Page
Abstract .. .... ... -- ....... -- ..........-.. ----............----- --- 1
Introduction _--- --- --- -----_---. --------------- 2
Purpose and scope --..---.-.--- --.----.. ----.---......-- -- 2
Previous work ---- ---- ------- ---- 3
Description of the area -...--.--.--.....------.--.... --- ----.---. 4
Rainfall -_..............-....--_...-_ _.... .......----- ----.. 6
Temperature ..------...--..- ...---............-_.---..-----. -- 8
Well-numbering system ...----............---.......---------...--- 8
Geology ............-. ..-_ ---......- ............ ..... 9
General statement _--- --------------- 9
Collection of data .--......----- ---......- --- --....... -.--- 9
Stratigraphy _......... ........------------.--- 11
Aquifers --------------.----------- --------------- --- --- 11
Sand-and-gravel aquifer ---......--.-- --------------- -------------. --- 11
Floridan aquifer _..-- -.... -_ -.. .....--- --.- ----.- 16
Aquicludes ----_- ......... ~____--..- .----- 18
Aquicludes within the sand-and-gravel aquifer ----- ---- 18
Aquicludes below the sand-and-gravel aquifer -- 20
Aquicludes within the Floridan aquifer __ -_----- 21
Aquiclude below the Floridan aquifer --------- -------- 21
Regional dip __- __ -__------ 21
Relation of geology to ground water -----..----.. ------. ---------- ---- 23
Movement of water -..............----.-- .------..----- ---- ----- 23
Relation of geology to quality of water ------23
Zones of fresh and salty water ---------------- 23
Mineralization and hardness of ground water ------- 24
Relation of quality of water to geologic history of the Gulf Coast -- 24
Surface water ..--..-----...... --------------...................----- 25
Collection of data ___-- 27
Flow-duration curves ------ -_29
Perdido River basin ------_______----- 30
Occurrence of water ------... ------.--- ---- --- 30
Mineral content ...-----... --. ..........----- -- ----.....- 39
Escambia River basin -. ..--------. ...--..-.....--- -.- 39
Occurrence of water --------------__--- --- ---- 39
Mineral content ....------.__ ...--.--- --..---.---------- 47
Blackwater River basin ...------...---- ----..---...----..--- 49
Occurrence of water .....---------------.--------- ----------. -- 49
Mineral content --------- --- ----------- 55
Yellow River basin _-----------------------55
Occurrence of water ---- -- ------------ 55
Mineral content --- ------- -------.----------- 55
Ground water -------- _-- --- -- --- -------- 56
Principles of occurrence ___ ----_--- 56
Hydrologic properties of the aquifers -- -56
Sand-and-gravel aquifer -----------57






CONTENTS


Page
Floridan aquifer --_-57
Movement of water ________-58
Ground-water velocities ______ -62
Areas of artesian flow _________63
Fluctuation of the water level _____ _______64
Temperature of ground water ______-__--72
Specific capacity _-_ --- --------------___ -- 73
Quantitative studies _-___ 73
'Mineral content ____76
Sand-and-gravel aquifer ------- 76
Floridan aquifer ___ 82
Use of water 82
Surface water ____________82
Ground water _________ 83
Sand-and-gravel aquifer __ 83
Use by industries ______ 83
Use by municipalities 85
Use by military operations __87
Use by agriculture ____87
Supplies for domestic use ____ _---___88
Floridan aquifer __88
Water problems ___89
Problems from natural causes _____ ________--------89
Periods of low rainfall ______ _89
Decline of water levels _____----__ --__-__ ------89
Salt-water encroachment ___...___ 89
Periods of high rainfall ____---------___---__-90
Man-made problems ------_____ 90
Large drawdowns ------------__-- 91
Salt-water encroachment ________91
Industrial waste disposal --- -------- -- 95
Potential water supplies ____96
Surface water _____----------____-- 96
Ground water _____-________--- --98
Sand-and-gravel aquifer ---------- 98
Areas of abundant fresh ground water ____ --_ 98
Factors which limit the amount of fresh ground water -____ 98
Floridan aquifer 99
References ___----________---____-- 101









ILLUSTRATIONS

Figure Page
1. Map of Florida showing location of Escambia and Santa Rosa counties 5
2. Graph of rainfall at Pensacola, Fla., and Brewton, Ala., showing monthly
averages, maximums and minimums, and yearly rainfall for the period
1926-61 ___ 7
3. Map of Florida showing the well-numbering system 8
4. Geologic sequence in Escambia and Santa Rosa counties, as shown by
representative log of oil test well near Pensacola 10
5. Map of Escambia and Santa Rosa counties showing locations of selected
wells from which information was obtained and the water supplies that
can be developed from wells in the sand-and-gravel aquifer __ 10
6. Geologic section across Escambia and Santa Rosa counties showing aqui-
fers and aquicludes along section A-A' in figure 11 _12
7. Geologic section along the Gulf Coast from Mobile Bay to the Choctaw-
hatchee River showing aquifers and aquicludes 14
8. Geologic section showing faces changes and zones of relative permeabil-
ity and impermeability in the upper part of the sand-and-gravel aquifer
along the Perdido River, Escambia County ____ ______ 15
9. Map of Escambia and Santa Rosa counties showing contours on top of
the lower limestone of the Floridan aquifer 18
10. Map of Escambia and Santa Rosa counties showing contours on top of the
Miocene clay units -_ --- 20
11. Map of Escambia and Santa Rosa counties showing contours on top of the
Bucatunna Clay Member of Byram Formation __ 22
12. Approximate average annual runoff, in inches, from areas within Escam-
bia and Santa Rosa counties __----- 26
13. Runoff in inches for 1961, a year of high runoff, and for 1956, a year of
low runoff, from areas within Escambia and Santa Rosa counties --- 27
14. Basin map of Perdido, Escambia, Blackwater, and Yellow rivers _--- 28
15. Graph showing periods and types of surface-water records in and near
Escambia and Santa Rosa counties ___ __- 29
16. Map of Escambia and Santa Rosa counties showing surface drainage and
data-collection points _-- ---------- 30
17. Flow-duration curves for 5 streams in Escambia County 31
18. Flow-duration curves for 5 streams in Santa Rosa County -- 32
19. Channel-bottom profile for lower Perdido River ------- ---- 33
20. Regional flood frequency curves for the Perdido, Escambia, Blackwater,
and Yellow rivers _- ---- 35
21. Low-flow frequency curves for Perdido River at Barrineau Park,
1941-61 __ 36
22. Graph of the minimum, average, and maximum monthly discharge of
the Perdido River at Barrineau Park, 1941-61 37
23. Channel-bottom profile for lower Escambia River 41
24. Channel-bottom profile of Pine Barren Creek ----- --42
25. Discharge available without storage, Pine Barren Creek near Barth,
1952-61 _____ 43
26. Mass-flow curve for Pine Barren Creek near Barth, 1952-58 44






ILLUSTRATIONS AND TABLES


Figure Page
27. Graph of the minimum, average, and maximum monthly discharge of the
Escambia River near Century, 1935-61 __ 46
28. Relation of daily chloride content in water in Escambia River at Chem-
strand plant to streamflow at State Highway 4 near Century, October-
December 1959 and October-December 1960 __ 48
29. Channel-bottom profile of Pond Creek 50
30- Low-flow frequency curves for Big Coldwater Creek near Milton,
1938-61 52
31. Graph of minimum, average, and maximum monthly discharge of Big
Coldwater Creek near Milton, 1938-61 53
32. Channel-bottom profile of lower Blackwater River 54
33. Water levels in an artesian well and two nonartesian wells drilled into
the sand-and-gravel aquifer in northern Escambia County and graph of
monthly rainfall at Pensacola __ 60
34. Cross section showing geology and hydrology in northern Escambia
County 61
35. Hydrograph of wells 037-645-1 and 032-648-1 ___ 65
36. Hydrographs of wells 031-716-1, 036-719-1, and 036-716-1 and graph of
yearly rainfall at Pensacola _____67
37. Hydrographs of wells 024-715-1, 024-715-2, and 023-716-2 ..--- 69
:38. Hydrograph of well 021-709-8 and graph of the rainfall at Pensacola 71
39. Graph showing theoretical drawdowns in the vicinity of a well 76
40. Map of Escambia and Stanta Rosa counties showing mineral content of
water from the sand-and-gravel aquifer -- 77
41. Map showing types of water from wells in the sand-and-gravel aquifer 78
42. Graphs showing chemical composition of water from wells in the sand-
and-gravel aquifer from Molino to McDavid ------- 81
-3. Map of Escambia and Santa Rosa counties showing the amount of ground
water used daily for industrial and public supplies during 1958 and
1962 ____ 84
44. Graph showing pumpage from the sand-an-gravel aquifer by the City of
Pensacola, 1933-62 87
45. Cross section showing the decline of water levels in the vicinity of
Cantonment ______--- 94



TABLES
Table Page
1. Drainage areas and average flows of streams in Escambia and Santa
Rosa counties, Florida ------ 97









WATER RESOURCES
OF
ESCAMBIA AND SANTA ROSA
COUNTIES, FLORIDA

By
Rufus H. Musgrove, Jack T. Barraclough,
and Rodney G. Grantham


ABSTRACT
Escambia and Santa Rosa counties, the westernmost counties in
Florida, have an abundant supply of both ground and surface water of
excellent quality. A 4-year study was made to determine the quantity
and quality of the water and the possible effect of municipal and indus-
trial expansion on the water.
Over 8.5 bgd (billion gallons per day) of fresh water flow into the
200 square miles of estuarine bays from four major rivers. Only about 5
per cent of this water is used. The Escambia River, the fifth largest in the
state, has an average flow of over 4.5 bgd. Many smaller streams within
the area produce large quantities of water.
Most of the 87 mgd (million gallons per day) of water taken from
the ground comes from the sand-and-gravel aquifer. This aquifer extends
from the water table down to various depths ranging from 200 to 1,000
feet. In parts of this aquifer the water is confined under artesian pressure
by numerous layers of clay and hardpan. The sand-and-gravel aquifer
contains a large supply of exceptionally soft and unmineralized water.
The Floridan aquifer, consisting of limestones which underlie the
sand-and-gravel aquifer, contains a large supply of harder, more mineral-
ized artesian water, and is virtually untapped.
Recharge of the sand-and-gravel aquifer is by local rainfall. The
Floridan aquifer is recharged by rain falling in southern Alabama, 10 to
35 miles north of the area, and by downward leakage from the sand-and-
gravel aquifer.
Factors such as decline of the water table, salt-water encroachment,
and contamination of surface and ground water can greatly affect the
availability of water of good quality. Decline in the water table may be
caused by below-normal rainfall or heavy pumping of closely spaced
wells. Salt-water encroachment is likely to occur where heavy pumping






FLORIDA GEOLOGICAL SURVEY


of wells near salty bays or estuaries lowers the water table below sea
level. Contamination can be brought about by disposing of wastes
directly into rivers and bays, or by seepage from waste basins to the
water table.
Industries use about 60 percent of the ground water withdrawn from
the area: St. Regis Paper Company, the largest user in the area, pumps
31 mgd. Chemstrand, using 31.5 mgd, is the largest user of surface
water in the area. The large amount of surface and ground water being
used by industries and municipalities is only a small part of the usable
supply of the area.

INTRODUCTION

PURPOSE AND SCOPE
An immediate need of community and industrial planners in Escam-
bia and Santa Rosa counties is information on the water resources of the
area. It is presently known that the area has a large supply of surface
and ground water that is low in mineral content. However, because the
water needs of this fast growing section of Florida are becoming greater,
information about other characteristics of the water must be made avail-
able so that the area may realize its full industrial potential without
creating problems caused by permanently lowered water levels, salt-
water encroachment, and pollution.
An investigation of the water resources of Escambia and Santa Rosa
counties was started in January 1958 by the U.S. Geological Survey in
cooperation with the Florida Geological Survey, Escambia and Santa
Rosa counties, and the city of Pensacola. This investigation was designed
to obtain, over a 4-year period, data on the occurrence, quality, and
quantity of surface and ground water. The information collected during
the investigation will serve two major purposes: (1) it will provide an
inventory of the water of the area; and (2) it will provide a sound basis
for planning development and use of the water resources of the area.
The purpose of this report is to make available information on the
quantity and quality of water in the area collected prior to 1962. It
contains a brief discussion of climate, a geologic description of the area,
information on streamflow and streamflow characteristics, principles of
the occurrence and movement of ground water, properties of the
ground-water aquifers, and chemical characteristics of the water re-
sources of the area. It discusses present use of water, some existing
problems associated with water, and potential water supplies of the area.






REPORT OF INVESTIGATIONS No. 40


PREVIOUS WORK
The earliest published report that describes the water resources of
Escambia and Santa Rosa counties was by Sellards and Gunter (1912);
it discusses the water supply of west-central and west Florida. This
report describes the physiography, drainage, water wells, and soils of
Escambia and Santa Rosa counties. It contains information, on wells in
Santa Rosa County at Bagdad, Blackman, Cobb, Milligan, Milton, Mulat,
Pace, and Robinson Point. Data are supplied for wells in Escambia
County at Cantonment, Bohemia, Molino, Muscogee, Pine Barren, Mc-
David and Pensacola, including chemical analyses of water from several
of these wells. The report also contains a map (p. 95) showing areas
of artesian flow in the two counties.
The following year (1913) Matson and Sanford published a report
on the geology and ground water of the entire State. They briefly de-
scribe the physiography, geology, and water supply of Escambia and
Santa Rosa counties (p. 301-304; 401-403). Data on typical wells and
general information on water resources of selected towns are tabulated
for each of the two counties.
Streamflow records have been collected on the Escambia River since
1934, on Big Coldwater Creek since 1938, and on the Perdido River
since 1941. Daily records of flow for these rivers are published by the
U.S. Geological Survey in the annual series of water-supply papers.
The first detailed investigation of ground water in the area was made
by Jacob and Cooper (1940). The report contained a section on geology
by Sidney A. Stubbs. The study included pumping tests of both the
drawdown type and the recovery type to obtain coefficients of trans-
missibility and storage for the aquifer in the vicinity of Pensacola. Since
1940, continuous and periodic measurements have been made of the
water levels in wells as far north as Cantonment to determine the effect
of rainfall, pumping, barometric pressure, and tides. Jacob and Cooper
also had chemical analyses made of water from several wells and
studied the encroachment of salt water from Bayou Chico into wells of
the Newport Industries and of the U.S. Navy.
The mineral spring at Chumuckla in Santa Rosa County is briefly
described by Ferguson, Lingham, Love, and Vernon (1947) in their
report on the springs of Florida.
Heath and Clark (1951) made a detailed investigation of the poten-
tial yield of ground water in the vicinity of Gulf Breeze on Fair Point
Peninsula, Santa Rosa County. Twenty test wells were drilled across the
peninsula, and periodic water-level measurements were made to obtain






FLORIDA GEOLOGICAL SURVEY


profiles of the water table. Heath and Clark conducted quantitative
studies to determine the effect of pumping in relation to salt-water
encroachment and to determine how much ground water could be
pumped from wells. They give a brief but adequate discussion on the
geology and cover such topics as use and quality of ground water.
Chemical analyses of ground water in the two counties have been
published by the U.S. Geological Survey (Collins and Howard, 1928)
and by the Florida State Board of Conservation (Black and Brown,
1951). Black, Brown, and Pearce (1953) give a short description of the
intrusion of salt water into wells of the Newport Industries and of the
U.S. Navy near Pensacola. Chemical analysis of water from Pensacola
city wells was published in a report by Collins (1923, p. 33). Another
analysis of water from these wells was published by the U.S. Geological
Survey (Lohr and Love, 1954, p. 111).
Stubbs (in Jacob and Cooper, 1940, p. 5-12) describes the upper 300
feet of geologic deposits in the southern half of Escambia County. Heath
and Clark (1951, p. 12-15) describe the same interval on Gulf Breeze
Peninsula. Cooke (1945, p. 232-233) describes a short measured section
exposed in the bluffs on the west side of Escambia Bay. He also noted
the presence of several Pleistocene marine terraces in Escambia and
Santa Rosa counties. MacNeil (1949) and Carlston (1950) likewise rec-
ognize the existence of several marine terraces in the area. Calver's
report on Florida kaolins and clays (1949, p. 24-28, 41-42) gives infor-
mation on clays in Escambia and Santa Rosa counties and indicates which
clays he believes have commercial value. The first detailed geologic study
of Escambia and Santa Rosa counties was made by Marsh (1962) in
connection with the comprehensive investigation of the water resources
of the area. An interim report of that investigation (Musgrove, Barra-
clough, and Marsh, 1961) summarizes the geology and water resources
of the two counties. Barraclough and Marsh (1962) describe the geology
and water resources of the southern half of Escambia, Santa Rosa,
Okaloosa, and Walton counties.


DESCRIPTION OF THE AREA

Escambia and Santa Rosa counties are in the extreme northwest
corner of Florida (fig. 1). Escambia County is the westernmost county
in the State and is bordered by Alabama on the west. Both counties
border on Alabama to the north and on the Gulf of Mexico to the south.
Water courses serve as boundary lines on three sides of Escambia County






REPORT OF INVESTIGATIONS NO. 40


and two sides of Santa Rosa County. The Perdido River is the boundary
line between Florida and Alabama on the west and the Escambia River
separates the two counties. Santa Rosa is the larger, but less populous
county, with 1,151 square miles and a 1960 population density of 25.6
persons per square mile. Escambia County covers 759 square miles and
had a 1960 population density of 229 persons per square mile.


Figure 1. Map of Florida showing location of Escambia and Santa Rosa counties.

The two major cities in the area are Pensacola and Milton. Pensacola,
located in southern Escambia County on Pensacola Bay, had a population
of 56,752 in 1960. Greater Pensacola includes several small suburban
communities and thus has a much greater population than Pensacola
proper. Milton is the largest town in Santa Rosa County, with a popula-
tion of 4,108 in 1960.
Much of the land in the southern part of the area is less than 30
feet above sea level. Bays, low marshy areas, peninsulas, and islands with
long shorelines characterize this section. Estuarine bays extend inland
some 20 miles and cover over 200 square miles. Santa Rosa Island is
about half a mile wide and 55 miles long and extends from the mouth






FLORIDA GEOLOGICAL SURVEY


of the Pensacola Bay eastward. Sand dunes on the island are as high as
55 feet above sea level. North of Pensacola the land is hilly and well
dissected with streams that drain toward the Pensacola area. The eleva-
tions of the streambeds are sea level for distances of 30 to 40 miles inland
from the coast. The hills 20 miles inland are about 150 feet above sea
level, becoming higher to the north. The highest land elevations, 290 feet,
are along the northern boundary of the counties.
Agriculture is the principal industry of the northern half of the area.
Much of the area is devoted to forest. The Blackwater River State
Forest occupies the northeastern quarter of the Santa Rosa County. Row-
crop farming is prevalent throughout the northern half of the area. In-
dustrial operations predominate in the section south of Cantonment and
Milton. Chemicals, synthetic fibers, and paper are the major products of
the local industries. Raw materials from many parts of the State are
shipped to the industrial area around Pensacola for processing and
manufacturing. Military operations, tourists, shipping, and fishing also
contribute to the economy of the area.

RAINFALL
To evaluate the effect of rainfall on the water resources of the area, a
study was made of records collected by the U.S. Weather Bureau at
two stations for a 36-year period, 1926-61. Data for these two stations
are presented in graphical form in figure 2. The rainfall data at Pensacola
were selected to represent the rainfall in the southern part of the area
along the coast. Data from the Brewton station, located in Alabama about
10 miles north of the State line, were selected to represent the rainfall
farther inland.
Within the two-county area there seems to be only minor long-term
variations in amounts of rainfall. The difference between the Pensacola
and Brewton averages for the 36-year period is only 0.46 inch. The shorter
the period of time for which rainfall is measured at any two points, the
greater the difference may be. A 1-year period can show uneven distri-
butions. For example, in 1953 Pensacola received one-third more rain-
fall than Brewton. The pattern was reversed in 1929 when Brewton had
87.18 inches and Pensacola had a below-average rainfall of 60.79 inches.
The average rainfall, based on the 36 years of record at the Brewton and
Pensacola stations, is about 63 inches per year. The year-to-year variation
can be great at any one point. For example, the highest and lowest an-
nual rainfall occurred in successive years at Pensacola-90.41 inches in
1953 and 28.66 inches in 1954.







REPORT OF INVESTIGATIONS No. 40


PENSACOLA, FLA.
-- i 1001---------- -----------
soo

= BO -------- ------1 I ---- ~ ----il-
S36-
i -,.
__- .* ,* ,- F. S- _~ ~_-- *- -- -
W -- -
I *'* iT i i *




NIII 0 o- o
II ,^ -HIIIIIllIt


a a 6


BREWTON, ALA.
25 100

to MAXIMoUM so I

2 z





0 0

Figure 2. Graph of rainfall at Pensacola, Fla., and Brewton, Ala., showing monthly
averages, maximums and minimums, and yearly rainfall for the period 1926-61.


The pattern of seasonal distribution is the same over the entire area,
the wettest periods occurring in early spring and late summer and the
driest in October and November. Except during October and November,
an average rainfall of at least 4 inches each month can be expected.
October and November have an average rainfall of about 2.9 inches and
3.8 inches, respectively. An average rainfall of over 6.0 inches occurs dur-
ing March, July, August, and September. July has the highest average,
with 7.4 inches. There is always the possibility, however, of having a dry
month during normally wet seasons or a wet month during seasons
which are usually dry. For example rainfall in October has varied from
near zero to a maximum of 20.5 inches at Pensacola, and March,
normally a wet month, has experienced as little as 0.9 inch of rainfall.
Another interesting aspect of the rainfall of the area is the high
intensity-as much as 0.6 inch has been measured during a 5-minute
period. Rainfalls of 3.5 inches during a 1-hour period and daily rainfalls
in excess of 6.0 inches are not uncommon.


N VO






8 FLORIDA GEOLOGICAL SURVEY

TEMPERATURE

Temperatures in the area are mild. The average annual temperature
at Pensacola is 68'F. Average monthly temperatures vary from a high of
810F in July and August to a low of 54F in December and January. The
extreme temperatures recorded at Pensacola have been as high as 103F
and as low as 7F; however, they seldom rise above 100F or drop
below 200F. On the average, 275 frost-free days occur annually. Winter
temperatures may be as much as 10F higher along the coast than in
the northern part of the area.


WELL-NUMBERING SYSTEM

The well-numbering system that is derived from latitude and longi-
tude coordinates is based on a state-wide grid of 1-minute parallels

C ees 'A 1-9hde -eT of the Gree-nr Engl-nd. pr-me m-4d-an

'"G EOR A
^^*^ r-;--^ l'_r< ...--. :.l --"



Figue /. .ap o d s' t w m i



45 V-
:9-.c __ ....... .-............. ..-- ..i .oo' "' .... O







1: :+ +
S::::::::::::. .::::::::L -:1: 31: + .' '. ', ......-

~ ?---~. -rt i -- -.





.. ... 3__ .. ....

.. 2r o. s .es .




Figure 3. Map of Florida showing the well-numbering system.






REPORT OF INVESTIGATIONS No. 40


of latitude and 1-minute meridians of longitude. The wells in a 1-minute
quadrangle are numbered consecutively in the order inventoried. In
Florida, the latitude and longitude prefix north and west and the first
digit of the degree are not included in the well number.
The well number is a composite of three numbers separated by
hyphens: the first number is composed of the last digit of the degree
and the two digits of the minutes that define the latitude on. the south
side of a 1-minute quadrangle; the second number is composed of the
last digit of the degree and the two digits of the minutes that define
the longitude on the east side of a 1-minute quadrangle; and the third
number gives the numerical order in which the well was inventoried in
the 1-minute quadrangle (fig. 3).

GEOLOGY
GENERAL STATEMENT
In Escambia and Santa Rosa counties, a thick sequence of sand,
gravel, and clay extends from the surface to as much as 1,000 feet
(fig. 4). Nearly all the wells in this area tap permeable sediments within
this sequence-referred to as the sand-and-gravel aquifer (Musgrove,
Barraclough, and Marsh, 1961). In the northern half of the area, the
sand-and-gravel aquifer lies on the upper limestone of the Floridan
aquifer, but in the southern part, the two aquifers are separated by a
thick clay unit of Miocene age which serves to confine the water that
is present in the upper limestone of the Floridan aquifer. An extensive
clay bed, the Bucatunna Clay Member of the Byram Formation, under-
lies the upper limestone of the Floridan aquifer and forms an aquiclude
throughout the area (Marsh, 1962).'the lower limestone of the Floridan
aquifer underlies the Bucatunna and rests upon relatively impermeable
clay and shale. Within the area, no fresh-water aquifers occur below the
lower limestone of the Floridan aquifer. A more detailed report of the
geology of the Florida Panhandle was prepared by Marsh.

COLLECTION OF DATA
Information has been collected on about 600 water wells in this
area. Figure 5 shows the location of the wells in Escambia and Santa
Rosa counties. They range in depth from about 15 feet to over 1,800
feet but most of them are between 30 and 300 feet deep. They range in
diameter from 1%i inches to 30 inches. Most of the domestic-supply wells
are 1, to 4 inches in diameter and most of the industrial supply wells are









FLORIDA GEOLOGICAL SURVEY


Sand, !:ght-brcan, very coarse; -
and gravel


Sand, ':ght grey, fine to very coarse;
mollusk shells
G-- I Coy, sandy -
Sand, very coarse; shells; and gravel

Mollusk shells with some fine to very
Coarse sand
LJ
;CC
o Grave! and shel:s and medium
S to very ccarse sand
7 Cv d sell gfrayg -
S Gravel =rd sell fragments


LJ
0 U
-00

0


,:cy, gray, sandy


Limestone, gray:sh white, and dark
gray clay

Limestone, light gray, fossils rare

ana, medium to very corse, and
tfne crave
Limestone, grayish white, some
crominifers in lower half



Clay, dark gray; a little pyrite and
carbonaceous material


Limestone, white, coundant
foraminifers


AOUICLUDE
(Cloy units of Miocene age
absent in northern half of Escambia
and Santa Rosa Counties)


LOWER LIMESTONE
OF THE
FLORIDAN AQUIFER


Figure 4. Geologic sequence in Escambia and Santa Rosa counties as shown
by representative log of oil test well near Pensacola.


o SCO
u acc-

0


zCCC






:2CC -


3 3CC-


-CC-

4CC




.6CC-


'BCC
;acc-


9CC-


2CCC -












3100


-i

*L































,2 Well and well number
- "Area where bel 00 gp, or


Areas where wells of 100 to 250
.HII^LL








.
















EXPLANATION
'2 Well and well number
m Areas where wells of 1000 gipm or
mwaeore capacity cn be developedraw
Areas where wells of 250 to 1,000en
gpnm capacity can be developed
Areos where wells of 100 to 250
gpm copocily con be developed.
*N Areas where large quantities of
water ore withdrawn
A r Areas subject to sal-wOater encroach-
ff ment if large-caupacity wells ore
closely spaced and heavily pumped,
Small to moderate supplies of water
can be developed.










GULF BE
7 --- --- I-
U
G


BOGIv


7T


CHUMUCKLA


""-'^L;0 :tm """ ztL""" '"":^ i1 {L""zti/--itzit


DI VKN ~-I ~


,k, 1 k


0 2 3 4 5 6 7 8 9 10 miles

- I l I I I I I I I I I I I I I i i i I I I I I


U Fr L I ~-- ---__ -- -,


87000


Figure 5. Map of Escarubia and Santa Rosa counties showing locations of selected
wells from which information was obtained d nd the watcr supplies that can be
developed from wells in the sand-and-gravel aquifer.


m


H __( 8.0 .4.. -1


3100'


NZ


4


S I I


30a1'


87040


S30010'
6045'


m


Fy~ ~1


I---l--c--t- -I--, ,+--t--~


J I H J I J -- l! 1 1 111 1 1 7 1 1-_


*^^.ym r -nr 1- 1@14 '^-TIP-in I^


r


H ri ( I


W0' 86'45'


+h ,^1


tI N .1.


Its!F~ BY
PE5OA FC


0


II


9 A M I A C 0 N Y A L A AM A- ..


S0o N TY 5 SANT RO UN

I -. ....r ,
?A
y "C NT

-H I Il I I Y -'







REPORT OF INVESTIGATIONS No. 40


10 to 24 inches in diameter. About 99 percent of the wells draw water
from the sand-and-gravel aquifer and the rest draw water from the
Floridan aquifer.
The larger-diameter wells tapping the sand-and-gravel aquifer are
constructed by drilling an open hole until permeable strata (generally
coarse sand or gravel) are encountered. Screens are then set in these
permeable zones. Almost all of these wells are equipped with screens.
The wells obtaining water from the Floridan aquifer are constructed
by drilling an open hole into the limestone, then casing the well to the
top of the limestone. The water is obtained from the uncased limestone
section. Sometimes an open hole is drilled to the top of the limestone,
the casing is firmly seated into the limestone, and drilling is continued
into the limestone below the bottom of the casing.
In 1959 and 1960, the U.S. Geological Survey contracted to have 31
test wells drilled, by the rotary method, in Escambia and Santa Rosa
counties. There were three main purposes for these test wells. First,
they helped to delineate aquifers and aquicludes in parts of the area
where little or no geologic information was available. Geologic logs of
wells were compiled from an examination of rock cuttings that were
collected at intervals of 5 or 10 feet. Fossils were picked from the rock
cuttings and were identified to determine the ages of the geologic for-
mations. Electric logs of the two deepest wells were made to determine
accurately the position of the clay layers and permeable zones. Second,
these test wells were used to establish a grid of water-level observation
wells in areas where information on water levels was needed. Third, 20
of the wells in Santa Rosa County were used to determine the water
budget (water gains and losses) for a small topographic drainage basin.
A total footage of 5,175 feet was drilled, and the depths of the wells
ranged from 32 to 750 feet.


STRATIGRAPHY
AQUIFERS
Sand-and-gravel aquifer.-Virtually all of the wells in Escambia and
Santa Rosa counties draw their water from the sand-and-gravel aquifer.
This aquifer extends from the surface to various depths, ranging from
200 feet in the area 7 miles northwest of Milton to 1,000 feet in the area
14 miles northwest of Milton (fig. 6). In the northern half of the area,
the sand-and-gravel aquifer overlies a thin limestone of late Oligocene
age (the upper limestone of the Floridan aquifer), but in the southern






















I I IL I I f" ,a -I
I/ ? R ~ 1600





4 1

IV oo
1.a400
1,600


CLPA)
EXPLANATION
? I L 4 L I I 1' 9 lO mimi
Length of I clian abooual mnI
Vtricaal lalurall, ooulal 31 Ii as
SeClln iakln dinclly do 'n li rn itnal dill
Canlocti lluld on awll cultlmngl ld elgtllae lII
]I II Tha i 1i polgaeflid fnam
Naimal,, al faorm n mndCate t ni plan s Ailmos alq i smile ..
lilIOna ol mowa mInIl ata Itiea II at u Intoa plant f Uncoaa miiy
section


200


.j 600

W00
1AW
1.0a

Q I.200.


SAND AND -


GRAVEL


Figure 6. Geologic section across Escambia and Santa Rosa counties showing
aquifers and aquicludes along section A-A' in figure 11.






REPORT OF INVESTIGATIONS No. 40


half of the area the sand-and-gravel aquifer rests upon a thick clay unit
of Miocene age (fig. 7). The aquifer ranges in age from Miocene to
Recent.
Abrupt faces changes are characteristic of the sand-and-gravel
aquifer. Although composed predominantly of sand, the aquifer contains
numerous lenses and layers of clay and gravel that are as much as 60
feet thick. The discontinuity of the sediments in the sand-and-gravel
aquifer is shown in figure 8. This is a detailed geologic section of the
uppermost 100 feet of the aquifer along the Perdido River in west-
central Escambia County. The cross section is based on rock cuttings
and electric logs of 20 test wells. These wells were drilled for the St.
Regis Paper Co. to test the infiltration characteristics of the ground
along the Perdido River. The logs were made by the firm of Leggette,
Brashears, and Graham, consulting ground-water geologists. As can be
seen from the cross section, irregular lenses of gravel and clay extend
for short horizontal distances. For example, one gravel lens that is 20
feet thick is only about 200 feet long. Well logs of the sand-and-gravel
aquifer elsewhere indicate that this cross section is fairly representative
of the aquifer throughout the area.
The uppermost 5-20 feet of the sand-and-gravel aquifer differs
markedly from the underlying beds. This upper part consists of light
tan, fine to coarse sand that is soft and loose in contrast to the hard,
reddish brown, pebbly sand that underlies it. In many places, the light
tan sand has been removed by erosion, leaving the hard reddish brown
sand exposed as a flat surface.
The sand-and-gravel aquifer consists predominantly of quartz sand,
ranging from white to light brown or reddish brown. Although some
beds of sand are moderately well sorted, the unit as a whole is generally
rather poorly sorted. The grains range from very fine to very coarse and
are commonly mixed with granules and small pebbles of quartz and
chert. The sand grades laterally into stringers and lenses of gravel which
are made up chiefly of pea-sized pebbles. In addition to the large lenses
of clay within the aquifer, small stringers of white to gray clay are
scattered throughout. Fragments and layers of black lignite are found
occasionally and at many places throughout both counties layers of black
carbonaceous sand and gravel, containing twigs and bits of coal, are
exposed at the surface. These layers range in thickness from a few inches
to more than 2 feet.
It seems likely that the materials in the upper part of the sand-and-
gravel aquifer were deposited in an environment similar to that of the
present-day Mississippi River delta. This is suggested by the rapid faces















BA.r1.". :0 Nrr FiCAMPA C*I Nr AAJT.1 SAY A A P CCOh0,fr I :0U.Ir fA ;, '
,ASll A &a AI I IA i

0- OAP Ili -L 0
SAN 0 ANiD -- GRAVEL AQUIFER Yea 000
2 00- .-- ... .......... 2.00
60020
000 M C~ N~ ~ ...-...........Dc
400F 400
6- 000 150




240
800- Y eOO
1000 C( E AOLFR uIFFRi~lo
S12600
14 00- NQIIAI o200
M30t 0 r 0014
41500iiAN AWUFER
leoo O,,LtOE 5a J OIAS OFN F LOR10N 10
t,2000- jp? L~C 00
t~2OWLVER C~Y2200

2600i~LE: 20
2800.-21BO
3000-i
y I;ie a to s r 3000
WOO-anr


EXPLANATION
LInqI' at I soila 11 miles
V4nPIrhcal gaqq..afn aaut 52 tinns
-UMneformity


Well inclane dl?0 ton4 ci
1.01cna along lstre cd beai


0 0 20 30miles
Map rsnownq COi,,c aof cross uthan R-*R

Figure 7. Geologic section along the Gulf Coast from Mobile Bay to the Choctaw-
hatchee River showing aquifers and aquicludes.


0



;ti


,.,















6-- Portion of sand and grovel 60
aquufer shown by section r[a Cros section based an electric logs and sample logs ao test 4uM
ra- ve. .. wells drilled by the St Regis Paper Company in 1956 t in-
-. 00 .estigate infiltration Charactersties of the ground along
Iwon ,S ;OAN.UIFOGRVEL.I Grvel andnd n the Perddo River Logs were made by Leggette, R dd i.
OCE6aa-an- Sand geologists, New York) and correlated by Owen T Marsh CROSS sCION















*Relatively permem able zone
Sg120ry sO- 1or AY.s- 120
120- 6 m s Sr sand ad iand lay
L, 140 Clay 140 -





o- ....... ..... :. .
W20- ..20






00 1 m0e


140 _' 'm" m .r-140

Figure 8. Geologic section showing faces changes and zones of relative permeability
and impermeability in the upper part of the sand-and-gravel aquifer along the
Perdido River, Escambia County.








FLORIDA GEOLOGICAL SURVEY


changes, the absence of fossils, and the abundance of sand and gravel.
These sediments were probably deposited by a network of streams
whose channels were constantly shifting back and forth across the sur-
face of the delta. In this environment, clay was deposited in quiet pools
or abandoned channels while gravel was being laid down by swiftly
flowing streams nearby.
Parts of the sand-and-gravel aquifer have a rather high average
porosity and permeability and are thus excellent reservoirs for ground
water. The aquifer consists principally of relatively insoluble quartz
grains which accounts for the remarkably low mineral content and soft-
ness of this water. In contrast to the rest of Florida, the ground-water
conditions in Escambia and Santa Rosa counties are complicated by the
great lithologic variability of the aquifer. Ground water is under artesian
pressure where lenses and layers of clay, sandy clay, or hardpan overlie
a saturated, permeable bed. Ground water is under non-artesian con-
ditions where such clays and hardpan are absent or where the perme-
able bed is not completely saturated. It is not uncommon for a well to
tap both artesian and non-artesian water. Ground water in the sand-and-
gravel aquifer is derived almost entirely from rain falling in the area.
Floridan aquifer.-In the northern half of the area, the sand-and-
gravel aquifer is underlain by a thick sequence of limestones known col-
lectively as the Floridan aquifer. In the southern half of the area the
two aquifers are separated by a thick clay unit of Miocene age (fig. 4).
The Floridan aquifer in Escambia and Santa Rosa counties is divided
into two parts by an extensive clay bed (Bucatunna Clay Member of
the Byram Formation) near the top of the aquifer. The part that lies
above this clay bed was named the upper limestone of the Floridan
aquifer and the part below the clay was named the lower limestone of
the Floridan aquifer (Musgrove, Barraclough, and Marsh, 1961).
The upper limestone of the Floridan aquifer is chiefly the Chicka-
sawhay Limestone of late Oligocene age. Within the area, this formation
ranges in thickness from about 30 to 130 feet. Its upper surface is an
erosional unconformity of low relief which dips gently toward the
southwest at about 23 feet per mile. The Chickasawhay is typically a
brown to light-gray hard dolomitic limestone or dolomite with a distinc-
tive spongy-looking texture. It contains abundant shell fragments. Sev-
eral wells in the area obtain water from this limestone.
In the southern part of the area, the Chickasawhay Limestone is
overlain unconformably by a remnant of the Tampa Limestone of early
Miocene age. This is a cream-colored to light-gray, soft to hard, sandy







REPORT OF INVESTIGATIONS No. 40


limestone which contains shell fragments and abundant foraminifers.
The Tampa reaches a maximum thickness of 270 feet in southern Escam-
bia County. The Tampa contains several beds of clay which would re-
duce the effective porosity and permeability of the limestone. A few
wells in the southern part of the area obtain water from this limestone.
The upper limestone is recharged mainly by rain that falls in
Conecuh, Escambia, and Monroe counties, Alabama. This is the area
where the upper limestone comes to the surface. Additional recharge
comes from downward leakage of water from the sand-and-gravel aqui-
fer in northern Escambia and Santa Rosa counties, Florida. The move-
ment of the water in the upper limestone is generally southward and
southeastward.
The lower limestone of the Floridan aquifer in this area consists of
the Ocala Limestone and other limestones of Eocene age. The top of the
lower limestone, although an erosional unconformity, is a relatively flat
surface that dips gently toward the southwest (fig. 9). The lower lime-
stone rests unconformably upon shale and clay of middle Eocene age.
The lower limestone ranges in thickness from about 360 feet in central
Escambia County to as much as 1,200 feet in the northern part of Santa
Rosa County (fig. 6). Thus, unlike most sedimentary units along the
Gulf Coast, these limestones thin rather than thicken downdip. The
lower limestone is white to grayish cream and is rather soft and chalky.
Well samples contain as much as 30 percent very fine to very coarse
sand, but some of this probably caved from above during drilling. Sam-
ples also contain some gray clay. Lenses of hard light-gray shale occur
within the limestone, but these appear to be randomly distributed and
cannot be correlated from well to well over any great distance. Much of
this limestone consists of foraminifers, corals, bryozoans, ostracods, frag-
ments of echinoids and mollusks, and other fossils. Black phosphatic
grains are locally plentiful.
Much of the Floridan aquifer in Escambia and Santa Rosa counties
is composed of a porous and permeable coquina consisting of fossil
fragments. This aquifer contains substantial quantities of ground water.
Most of the water in both the upper and lower limestones of the Flori-
dan aquifer is confined above and below by beds of relatively imperme-
able clay. Ground water in the lower limestone is also derived mainly
from precipitation that occurs 10 to 35 miles north of the area in
Conecuh, Escambia, and Monroe counties, Alabama, where the lime-
stone crops-out. The movement of water in the lower limestone is gen-
erally to the south and southeast.







FLORIDA GEOLOGICAL SURVEY


F P EXPLANATION
S F Number mcates depth to the top Norml fault
of he Ocala Lnsbone in feet -u U=Upthrown side; D=D nlhfrown side
below mean sea level
Contour represents the top of the
S -"- Ocala L nefoe an feet below Nolte All data from electric logs
mean sea level. Cctour iterval I00 feet.
SI I I I I 6I ,,,,
0- 0 1 2 3 4 5 6 7 9 I Om1 Geolc/ by 0 T Marsh

Figure 9. Map of Escambia and Santa Rosa counties showing contours on top of
the lower limestone of the Floridan aquifer.



AQUICLUDES

Aquicludes within the sand-and-gravel aquifer.-As shown by the
geologic section along the Perdido River in Escambia County (fig. 8),
the sand-and-gravel aquifer contains discontinuous layers and lenses of
clay and sandy clay. The clay strata range in thickness from a few inches
to several tens of feet. For example, the clay bed mined by the Taylor
Brick and Tile Co., Inc., of Molino in Escambia County is about 50 feet







REPORT OF INVESTIGATIONS No. 40


thick. The available data suggest that the clay and sandy clay strata
may range in length from a few feet to several miles.
Another type of relatively impermeable layer within the sand-and-
gravel aquifer is hardpan. This rock, formed by cementation of sand by
iron oxides precipitated from ground water, occurs extensively through-
out westernmost Florida and southern Alabama. This rock ranges in
thickness from a fraction of an inch to 4 feet. Little is known concerning
the lateral extent of these hardpan layers, but it is unlikely that any
layer extends for more than a few thousand yards. Although the rock is
dense, these layers are sometimes filled with many curiously shaped
cavities of uncertain origin. The rock is rust brown and is generally hard,
although some of it is soft. It is composed of iron oxides in the form of
limonite and goethite. Most "rock" on local drillers' logs is hardpan. It is
the only consolidated rock near the surface in westernmost Florida, and
it is occasionally used in the construction of stone walls and buildings.
The relatively impermeable layers of clay and hardpan affect ground
water in several ways. First, they reduce the average permeability of
the aquifer. Second, although ground water in the sand-and-gravel aq-
uifer probably is more or less hydraulically connected, owing to the dis-
continuity of the impermeable beds, these layers (assisted by the hy-
draulic gradient) cause the water beneath them to be under artesian
pressure. Third, where these layers lie at or near the ground surface,
they decrease recharge to the aquifer by reducing infiltration rates and
cause water to be retained in depressions, where it is evaporated. Sev-
eral hundred ponds, large enough to be shown on topographic maps,
dot Escambia and Santa Rosa counties. Considerable inconvenience and
damage is caused in some residential areas by ponding of water above
clay or hardpan layers after heavy rains. In some areas these layers
underlie perched water bodies and thus make small or moderate sup-
plies of ground water available at relatively shallow depths. Finally,
these layers are responsible for countless springs, which are typically
found at the heads of gullies and small box canyons called steepheads.
These canyons are notched into the plateau-like areas that are remnants
of marine terraces of Pleistocene age. Excellent examples of such steep-
heads are found on the Eglin Air Force Base, south of the Yellow River.
Here numerous small streams originate as springs that discharge along
clay or hardpan layers at the steepheads of the gullies. As most of these
springs occur at about the same elevation, 50 feet or so above sea level,
it seems likely that they are emerging along the same relatively imper-
meable layer. The gullies were formed by headward erosion from the
edges of the terraces.







FLORIDA GEOLOGICAL SURVEY


Aquiclude below the sand-and-gravel aquifer.-Two thick clay units
of Miocene age lie between the sand-and-gravel aquifer and the upper
limestone of the Floridan aquifer in the southern part of the area (figs.
6, 10). The observed thickness of this clay ranges from about 150 feet
on Santa Rosa Island near the Santa Rosa-Okaloosa county line to about
980 feet at a location 4 miles west of Pensacola. As shown by the
structure-contour map in figure 10, the upper surface of the thick clay
units generally dips to the southwest. The top of the clay units is only


EXPLANA1ION
Stll Nu.trO, ind-'o ol 0Dh to the. 1,V
Of t Io Mo0tcor Cloy. in Wl
s. u L belCO moon So Jvol
Contour *,psOlnl thy too tf the
.-JO--O M'occOn Cloy, in too bolow
moen Soo lovil
Contour inlotv 00 I flt

0 4 6 10 a, 1 o0.m Ada0 odrOmn 0 T Mortn
Figure 10. Map of Escambia and Santa Rosa counties showing contours on top
of the Miocene clay units.








REPORT OF INVESTIGATIONS No. 40


135 feet below sea level in the area 6 miles northwest of Milton and
1,000 feet below sea level in the southwest corner of Escambia County.
A few miles north of Cantonment, the clay interfingers with the
sand-and-gravel aquifer (fig. 6). The two clay units are separated by a
bed of sand that ranges from 20 to 160 feet thick.
The clay is gray to dark gray and contains much silt, very fine to
coarse sand, and some gravel. It is dated as Miocene on the basis of
mollusks and foraminifers. Apparently, this is one of the units that local
drillers sometimes call the "Blue Marl."
Aquicludes within the Floridan aquifer.-The Bucatunna Clay Mem-
her of the Byram Formation of middle Oligocene age (Marsh, 1962)
separates the upper and lower limestones of the Floridan aquifer and
underlies all of westernmost Florida and parts of Louisiana, Mississippi,
and Alabama. Within the area, the Bucatunna ranges in thickness from
about 45 feet in the northwest corner of Santa Rosa County to 215 feet
just north of Escambia Bay. The Bucatunna rests uncomformably upon
the eroded surface of the lower limestone of the Floridan aquifer and is
overlain conformably by the flat, even base of the upper limestone. The
Bucatunna consists of gray, soft, silty to sand clay containing foramini-
fers, ostracods, and a few mollusks. The unit crops out along a belt that
lies about 10 to 35 miles north of the area in Alabama.
Although much of the Floridan aquifer is porous, it contains zones of
dense rock which may have been caused by solution and re-precipita-
tion calcite. These dense layers serve to prevent or retard movement of
water and thus may be classed as aquicludes.
The lower part of the lower limestone of the Floridan aquifer con-
tains thick but irregular zones of gray, hard, slightly calcareous, silty
clay-shale as much as 300 feet thick. As these zones are near the base of
the aquifer and seem to be continuous, they have relatively little effect
on the water in the limestone. However, they reduce the average trans-
missibility of the aquifer (see p. 160).
Aquiclude below the Floridan aquifer.-The lower limestone of the
Floridan aquifer is underlain everywhere in the area by gray shale and
clay of middle Eocene age. The top of this shale and clay, although slop-
ing generally southwestward, undulates broadly implying that these
rocks were eroded before deposition of the overlying limestone (fig. 4).

REGIONAL DIP
The lack of exposures and observable bedding within the sand-and-
gravel aquifer makes it impossible to obtain the strike and dip of this









FLORIDA GEOLOGICAL SURVEY


unit. However, the top of the Bucatunna Clay Member presents a gen-
erally uniform, easily identifiable surface whose attitude can be com-
puted readily (fig. 11). This surface strikes about N. 65 W. and dips
about 30 feet per mile toward the southwest. The top of the lower lime-
stone of the Floridan aquifer also dips southwestward at 30 feet per
mile and has a strike of N. 60 WV. Probably the sand-and-gravel aquifer
has a gentler dip.


Figure 11. Map of Escambia and Santa Rosa counties showing contours on top of
the Bucatunna Clay Member of Byram Formation.


0 EXPLANATION
f Well A-A'Lf ol 0closs-section in g.r.e 6.
L % -,mat l t W 1 o N m ber i1nd5ote o l hl u ie Dtr ne," t d i
U-Liqhlroon .ao Op as tl 0 op olunn Cofy t. RaF)-d i.L oa d, d mte bp of
DIU D:zC,-*ro- sid Member. i w t men Bucalno Cloy Member
Conour ine tepresnts the aloude d the lop of
the BCatunna Clay Membe4 pn feel helo
Smeon s level Cnour inerl 100 feel.
Geology by O.n t I ot"i







REPORT OF INVESTIGATIONS No. 40


RELATION OF GEOLOGY TO GROUND WATER
MOVEMENT OF WATER
The direction of ground-water flow is determined by the pressure
head from point to point. The head, in turn, is determined by the hy-
drologic, geologic, and topographic conditions between the recharge and
discharge areas. The relative position of rock layers of greatly differing
permeabilities may have an important influence on the direction of
ground-water flow. Owing to the relative impermeable clay unit and
the Bucatunna Clay Member, which dip gently toward the southwest,
one might expect ground water in the Floridan aquifer to move south-
westward in the area. However, the movement of water in the Floridan
aquifer is to the south and southeast. The dip of strata in the sand-and-
gravel aquifer is so slight that ground-water flow in this aquifer is con-
trolled principally by differences in head resulting from local topographic
irregularities.
The location of four normal faults in the Jay area is shown on figures
9 and 11. These faults are extensions of the fault system around Pollard,
Alabama, where the Pollard oil field is located. Oil is produced in this
field from structural traps along the faults and comes from sands in the
Tuscaloosa Formation of Late Cretaceous age at a depth of approxi-
mately 5,400 to 6,000 feet below sea level.
Just how faults affect flow of the ground water is not known but
different resistivity readings on opposite sides of faults, shown by elec-
tric logs, suggest that some salty water may move upwards along faults
in the lower part of the lower limestone of the Floridan aquifer. How-
ever, water wells near the faults are not nearly deep enough to verify
this.

RELATION OF GEOLOGY TO QUALITY OF WATER
Zones of fresh and salty toater.-Most of the water in the sand-and-
gravel aquifer is fresh. The Floridan aquifer, however, contains sub-
stantial quantities of both fresh and salt water. In the northern part of
the area, the uppermost few hundred feet of the lower limestone of the
Floridan aquifer contains fresh water. At depths greater than about
1,200 feet, the water from this limestone is very salty. In the southern
part of the area, the lower limestone contains only very salty water.
Here the relatively impermeable Bucatunna Clay Member serves to re-
tard the vertical movement of water and thus to prevent salt water in
the lower limestone from moving upward and contaminating the fresher







FLORIDA GEOLOGICAL SURVEY


water in the upper limestone. The water in the upper limestone becomes
salty downdip. Although few samples of water from these salt-water
zones are available for analysis, the zones of relatively fresh and salty
water may be distinguished on electric logs. An analysis of more than
60 electric logs was made for this purpose during the present study.
Mineralization and hardness of ground water.-In addition to differ-
ences in salinity, ground water in the sand-and-gravel aquifer and in the
Floridan aquifer differs in amount of dissolved solids and hardness be-
cause of differences in lithology of the two aquifers. As might be ex-
pected, water in the Floridan aquifer (composed mostly of limestone)
is generally harder and more mineralized than water in the sand-and-
gravel aquifer, which is composed principally of relatively insoluble
quartz sand. As ground water percolates through the upper part of the
sand-and-gravel aquifer, it encounters very little soluble material and
remains soft and virtually unmineralized. However, harder and more
mineralized water comes from deeper wells in the sand-and-gravel aq-
uifer that penetrate sediments containing abundant sea shells. The
abundance of ground water remarkably low in mineral content has in-
fluenced several large industries to locate in Escambia and Santa Rosa
counties.
Relation of quality of water to geologic history of the Gulf Coast.-
For millions of years the Gulf coastal area has been slowly subsiding,
forming a vast sinking trough, or geosyncline. As the trough sank,
streams emptying into the Gulf of Mexico kept the trough nearly full
by dumping into it huge quantities of mud, sand, and gravel. According
to Howe (1936, p. 82), "These sediments have been concentrated along
a narrow zone paralleling the present shore, and, since the beginning of
the Eocene, have accumulated to a thickness which probably exceeds
30,000 feet [south of the Mississippi River] the region of the pres-
ent coastline has been depressed under the weight of these deposits to
almost three times the present maximum depth of the Gulf of Mexico.
The major axis of the Gulf Coast geosyncline approximately parallels
the Louisiana coastline "
Ground water in the Floridan aquifer in the Florida Peninsula be-
comes mineralized as it moves through soluble limestones. In Escambia
and Santa Rosa counties, however, these limestones have been depressed
hundreds of feet by the sinking of the Gulf Coast geosyncline. This
circumstance made it possible for rivers and streams to deposit the del-
taic sand and gravel which make up the principal ground-water aquifer
in westernmost Florida. The main area of subsidence did not extend far
enough to the east to depress the limestones of peninsular Florida.







REPORT OF INVESTIGATIONS No. 40


SURFACE WATER
Escambia and Santa Rosa counties have an abundant supply of sur-
face water of excellent quality flowing in the streams and additional
supplies are found in small natural ponds and a few man-made ponds.
Streams are the main source of fresh surface water, discharging an aver-
age of 8.5 bgd into the bays along the southern boundary of the counties.
Small reservoirs created by dams are few in number at present. How-
ever, much of the terrain lends itself well to the development of small
reservoirs, and more will probably be built as the economy of the area
expands. The bays along the coast cover more than 230 square miles and
provide excellent facilities for boating, fishing, swimming, and shipping.
The streams that flow into Escambia and Santa Rosa counties or
along their boundaries drain about 6,000 square miles before reaching
the counties. An average of slightly more than 10,000 cfs (cubic feet per
second), or 6.5 bgd, is brought into the counties by the surface streams.
Streams within the two counties pick up an average flow of 3,100 cfs, or
2.0 bgd, from the 1,700 square miles of land of the area.
The flow of 2.0 bgd that is derived from within the two counties is
equivalent to 25 inches, or 40 percent, of the 63-inch annual rainfall of
the area. The combined losses by evaporation, transpiration, and under-
ground flow averages about 38 inches per year.
Average unit runoff varies from basin to basin from 14 inches to 50
inches. The map in figure 12 shows approximate average annual runoff
in inches from stream basins within the two counties.
Runoff during an extremely wet year is about 2% times that for a
dry year. Figure 13 shows runoff in inches for 1956, a year of low runoff,
and for 1961, a year of high runoff. The 1956 rainfall was near normal
but the low runoff for that year reflected the rainfall conditions during
the two previous years, which were well below normal. The cumulative
deficiency of rainfall for the 3-year period 1954-56 was about 40 inches.
This 3-year deficiency in rainfall reduced the amount of direct surface
runoff and caused a decline in ground-water levels which in turn caused
a decline in the base flow of streams. Streams in this area have a high
rate of base flow that comes as seepage from the ground.
The surface waters of Escambia and Santa Rosa counties are of ex-
cellent quality, except in the coastal reaches where tides bring salt wa-
ter up the streams. The Escambia River coming out of Alabama brings
water of higher mineral content (about 100 ppm, parts per million);
however, this mineralization is diluted somewhat by the lower mineral-
content waters of the Florida tributaries.







FLORIDA GEOLOGICAL SURVEY


Figure 12. Approximate average annual runoff, in inches, from areas within Escambia
and Santa Rosa counties.


Most of the streams of the two counties originate in the highlands
and flow in sand and gravel-lined streambeds. The low solubility of the
sand and gravel results in water of very low mineral content, generally
less than 30 ppm. The mineral content varies seasonally. During the
rainy season the minerals in the water are diluted, but the color gen-
erally increases because of surface runoff. In the dry season the water
has a slightly higher mineral content, but very little color.
The quality of available surface water in the area varies from place
to place and from time to time. The seasonal fluctuations follow very
closely the pattern of rainfall. The discussion that follows is concerned
with the availability of surface water with respect to quantity and







REPORT OF INVESTIGATIONS No. 40


quality within the two-county area. Where possible, short-term records
were extended to long-term periods to obtain average flow figures and
flow-duration curves. Streamflow characteristics are discussed by basins
as outlined in figure 14.


Figure 13. Runoff in inches for 1961, a year of high runoff, and for 1956, a year of
low runoff, from areas within Escambia and Santa Rosa counties.

COLLECTION OF DATA
Streamflow data were collected at only four sites in Escambia and
Santa Rosa counties prior to 1958. The first stream gaging station was
started on the Escambia River at Century in 1934. In 1938 a station was.
established on Big Coldwater Creek near Milton, and in 1941 one was.







FLORIDA GEOLOGICAL SURVEY


Figure 14. Basin map of Perdido, Escambia, Blackwater, and Yellow rivers.

started on Perdido River at Barrineau Park. The collection of river
stages on the Escambia River near Gonzalez was started in 1951 and
streamflow records on Pine Barren Creek near Barth were started in
1952. Streamflow data were also collected at two nearby sites, Yellow
River near Holt (1934-1940) and Escambia Creek at Flomaton, Ala-
bama (1939-1951).
At the start of the present investigation in 1958, additional data-
collection sites were established to define streamflow conditions and to
determine in more detail the quantity and quality of the water supply
in the area. A list of data-collection sites and the length of record at each
site are given in figure 15. The map in figure 16 shows the location of
these sites.










REPORT OF INVESTIGATIONS No. 40


S STATION A.MA.
q. nl.

I B'you MPrcua Crook nonr I'an acola, la. 11.2

2 l1.Coldwator River near HMlton, Fla. 237

) nig Juniper Crook near Harold, Fla. 1l2

I Plf Junlpor Crook near Munnon, Fll. 36

5 plackvater River neor Holt, Fla. 276

6 BIrushy Creek near Walnut 11111, Fla. 49

' CNoo Crook nenr lPlurr Springa, Fa.

0 Carpenter Creek nonr Pononcola, Fin. .31 l

9 ftat Fork Coldvater Crook naor Munaon, Fin. 6I

10 klevoenile Crook near Fnoloy, Fla.

11 EacI bial Crook at Floiaton, Ale. 325

12 Ecam bl l River noar Century, Fla. 3,817

13 Kacmbia River near Gonzoloz, Fla. -

11I goeabia River near Molino, Fla.

15 Hurricane Branch near Milton, Fla. 2.95

16 Jacks Branch near Muocoge, Fla. 23.2

17 McDavid Crook near Barrineau Park, Fla 26.5

10 Moore Creek near Chumucklo, Fla. 22.0

19 Perdido River at Barrineau Park, Fla. 39

20 Perdido River near Nokomsi, la. -

21 Pine Barren Crook near lBrth, Fla. 75.5

22 Pond Crook near Milton, Fla. 58.7

2 Svootweter Crock near Mun=on, Fla. '5

24 Weat Fork Coldvator Crook at Cobbtown, Fla. ?9.5

25 Yellow River near lolt. Fla. 1,210


mo Streoamlow, stage Chescal aalyse

Figure 15. Graph showing periods and types of surface-water records in and near
Escambia and Santa Rosa counties.


FLOW-DURATION CURVES

Daily streamflow data are available at 10 sites with 4 to 27 years of

record. Escambia River near Century has the longest record. Records

from 9 of these stations were extended to the 27-year period, and figures







FLORIDA GEOLOGICAL SURVEY


of average flow and flow-duration curves were obtained from these ex-
tensions. The flow-duration curves and average flows for the 10 stations
are given in figures 17 and 18.


-,w' I- M W iof 0 ir@ I 4w w
Figure 16. Map of Escambia and Santa Rosa counties showing surface drainage and
data-collection points.

PERDIDO RIVER BASIN
OCCURRENCE OF WATER
The Perdido River, the westernmost stream in Florida, forms the
part of the boundary line between Florida and Alabama. The part of
the basin in Florida lies in a narrow band, 5 to 10 miles wide, along the
eastern side of the main channel in Escambia County. The four major
tributary streams on the Florida side of the river are Brushy Creek,
Boggy Creek, McDavid Creek, and Jacks Branch. Elevenmile Creek and











REPORT OF INVESTIGATIONS No. 40


GAGING STATION
.....L Brushy Creek near
Wolnut Hill, Fla.
_- 2 Escombla River near
Century, Flo,
- -&J.ocks Branch near
Muscogee, Fla.
.. 4,Perdldo River near
Barrlneou Park, Flo,
....... 5 Pine Barren Creek
near Barth, Flo,


DRAINAGE
AREA
SO. MI.
49

3817

23.2

394

75.3


AVERAGE FLOW FOR
27-YEAR BASE
PERIOD, 1934-61,CFS
95

6151

24

756

159,


001 0.05 02 0.5 1 2 5 10 20 30 4050 60 70 80 90 95 98 99995 99.9 99.99
PERCENT OF TIME DISCHARGE EQUALED OR EXCEEDED THAT SHOWN

Figure 17. Flow-duration curves for 5 streams in Escambia County.










32 FLORIDA GEOLOGICAL SURVEY



Bayou Marcus Creek flow into Perdido Bay and are included in the

discussion of the Perdido River basin.

The basin, outlined on the map in figure 14, covers 925 square miles.

Of this area, 236 square miles are in Escambia County, Florida. Streams


DRAINAGE
GAGING STATION AREA
SQ. ML
- -L Big Coldwoter Creek
never Mllion, Fml. 237
---2.Big Juiper Creek
near Munaon. Fla. 36
-...-. ackwoter Ri;ver
nesa Baker, Fil. 205
........4.Pond Creek pnar
M;ilon, Fla. 58.7
- S West Fork 81i Coldwater
Creek aor Cobbtoln, Fla. 315


AVERAGE FLOW FOR
27-YEAR BASE
PERIOD, 1939-61, CFS
534

65

320

78

.74


I














~II
; o -- -- ------ --- ----- --- -- -- ---







1,000




ioo
\
















lot
ZO- 0 0 0 0 -
\," i. .
1 ".. "






o~ ~ ~ .. .


90 95 98 99 99.5 99.9


PERCENT OF TIME DISCHARGE EQUALED OR EXCEEDED THAT SHOWN

Figure 18. Flow-duration curves for 5 streams in Santa Rosa County.


30,000


20.000 --


,,' "


to 00(


s



3


acOt 0.05a 02 O.S


za 30 40 so 60 70 80


99.99


--








REPORT OF INVESTIGATIONS No. 40


in the basin drain very hilly country. The hills are from 100 to 150 feet
above the stream valleys. The fall of the Perdido River streambed from
the Alabama-Florida State line to Muscogee is 150 feet for a channel
length of about 40 miles. The fall from Muscogee to Perdido Bay is 15
feet for a channel length of about 20 miles (taken from U.S.G.S. topo-
graphic maps).
Tidal fluctuations occur in the lower reach of the river. During
periods of low flow, tidal effects extend about 15 miles upstream from
Perdido Bay nearly to Muscogee. Tidal effect will extend the greatest
distance upstream during periods when the river is low and the tides
are at seasonal highs. The salt front, however, does not extend as far
upstream as the tidal effect.
The downstream, 10-mile reach of the main channel is generally
more than 10 feet deep, with holes extending to 45-feet depths. A depth-
profile graph of the lower 10 miles of the river is given in figure 19.






14 mli
13.m. Omi. (Mouth) ay









S--250--CSlitd. cu.lul; i p1 p. .14.
Iemi. mi.







9 --. 4- M. - --lo


-W e r
5. b.9n~


Figure 19. Channel-bottom profile of lower Perdido River.







FLORIDA GEOLOGICAL SURVEY


This depth-profile graph was obtained from a sonic depth-recorder mov-
ing along the centerline of the channel. The water-surface elevation in
the lower reach of the river during low stages fluctuates with tide from
about 0.5 to 1.5 feet above mean sea level.
Throughout its length the Perdido River channel is tortuous. The
low-water channel in the vicinity of Barrineau Park is about 150 feet
wide and winds through a thickly wooded flood plain that is half a mile
wide. The streambed is composed of sand and gravel and characterized
by alternate sandbars and holes.
The steep slope of the drainage basin causes high rates of direct run-
off. Consequently, floods in this basin are usually of short duration. A rise
in water level of 15 feet is not uncommon at Barrineau Park. The highest
flood of record reached an elevation of 51.5 feet above sea level in
March 1929. The usual low-water stage is 28 feet above sea level. Dur-
ing the flood of April 1955, which was the highest in the 20-year period
ending in 1961, the river reached a peak flow of 39,000 cfs at an eleva-
tion of 49.7 feet above sea level at the Barrineau Park gaging station.
Three days after this flood peak the stage had receded 17 feet and the
river was within its banks.
The consideration of floods and their effects on the area is an essen-
tial item in planning developments adjacent to the stream channel. The
probability of future floods can be predicted on the basis of floods that
have occurred in the past. From a study of the magnitude and frequency
of past floods, a means of estimating the frequency of floods has been
developed for Florida (Pride, 1958). Regional flood-frequency curves
applicable to this area have been developed from this report and are
presented in figure 20.
The sustained low-flow yield of the streams should be examined in
considering an area for development. If the minimum flow of a stream
during a reasonably long period of time is known to be above the an-
ticipated demand, the supply is adequate without storage. However, if
the minimum flow falls below the anticipated demand, either of two
measures can be undertaken. Storage reservoirs can be built to store
water during periods of excess flow for use during periods of deficient
flow; or, if the deficient flow is of short duration and occurs infrequently,
the use of water might be geared to the available supply.
The low-flow frequency curves given in figure 21 for Perdido River
at Barrineau Park, Florida, show the frequency of average flows for the
indicated periods. For example, a discharge of 250 cfs will occur as a
1-day average once in 2.4 years, or as a 30-day average once in 6.5 years.
The Perdido River basin yields copious quantities of water. The av-








REPORT OF INVESTIGATIONS No. 40


erage runoff at Barrineau Park is 26.0 inches per year. That is, the
average flow of 756 cfs for 1 year would cover the drainage area of 394
square miles to a depth of 26.0 inches. This is in comparison with the
State average runoff estimated to be 14 inches per year (Patterson,
1955). The high yield of the Perdido River basin can be attributed to
two factors: (1) a high annual rainfall-this area receives about 63
inches per year; and (2) the coarse sand and gravel surficial covering
that releases water to the streams as seepage from the water table or as
artesian flow from local aquifers.


200,000


100,000


50,000


10,000


5000


cn 2000 1-I 1 1 1-
50 o o00 500 10000 50o 10,000
DRAINAGE AREA, IN SQUARE MILES
Figure 20. Regional flood-frequency curves for the Perdido, Escambia, Blackwater,
and Yellow rivers.

The pattern of flow with respect to time is similar to that of rainfall.
March and April are by far the months of highest runoff, and October is
the month of lowest runoff. The bar graphs in figure 22 show the aver-
age, maximum, and minimum monthly discharges for the Perdido River
at Barrineau Park for the 20-year period 1941-61.
The flow-duration curve for Perdido River is given in figure 17. The
slope of this curve indicates the variability of flow. This stream has high








FLORIDA GEOLOGICAL SURVEY


flood flows, and relatively stable flows during medium and low-water
periods.
The average flow from the entire Perdido River basin is estimated to
be 1,730 cfs. About one-fourth of this, or 440 cfs, is derived from the
area lying within Escambia County.

800



700
a Drainage area: 237 sq. mi.
Z Average flow: 534 cfs.
0 -

600


S ~ \ LOW-FLOW FREQUENCY
5I". Example: For a 20 year recurrence
S500 interval the I-day minimum
u I \ flow is 160 cfs and the 12-
month minimum flow is
S 310 cfs.
o 400



t 3001 12 Month


4 Month
200 2 Month
SI Month
I Day
toolI

10.01 1.05 1.1 1.5 2 3 4 6 8 10 20 30 40 50
RECURRENCE INTERVAL, IN YEARS

Figure 21. Low-flow frequency curves for Perdido River at Barrineau Park, 1941-61.

Brushy Creek, entering the Perdido River 13 miles above Barrineau
Park, drains 75 square miles-53 square miles in the extreme northwest
corner of Florida and 22 square miles in southern Alabama. At the gaging
station near Walnut Hill, the long-term computed average flow was 95
cfs from the drainage area of 49 square miles. The average flow from the
entire basin is estimated to be 140 cfs, of which about 100 cfs comes
from Escambia County and about 40 cfs from southern Alabama. The 4
years of streamflow records on Brushy Creek were adjusted to long-term









REPORT OF INVESTIGATIONS No. 40


J F M A M J J A S 0 N D


Figure 22. Graph of the minimum, average, and maximum monthly discharge of the
Perdido River at Barrineau Park, 1941-61.


2600





2200



2000



1800

MAXIMUM

1600 -



1400



1200 -- -- __





AVERAGE
800



6000 -
600 -- .... : --MINIM M
S:: : ." -M- M-INIMUM

n0- __ -


I







FLORIDA GEOLOGICAL SURVEY


records on the basis of 27 years of records for Escambia River near Cen-
tury. The flow-duration curve given in figure 8 was also adjusted on the
basis of this long-term station.
Boggy Creek drains an area of 27 square miles. Based on unit runoff
per square mile of nearby streams, the average flow of Boggy Creek is
estimated to be 50 cfs.
McDavid Creek drains 34 square miles in Escambia County and
flows into the Perdido River a mile above Barrineau Park. The average
unit runoff from this basin is estimated, on the basis of discharge meas-
urements and correlation with records of nearby basins, to be 1.9 cfs per
square mile, giving a total flow from the basin of 65 cfs.
Jacks Branch, a tributary entering the Perdido River west of Canton-
ment, has the lowest runoff of any stream gaged in the Perdido River
basin. The average unit runoff was computed to be 1.0 cfs per square
mile. The Jacks Branch basin covers 24 square miles and produces an
average flow of 24 cfs. The minimum daily flow measured at the gaging
station is 3.0 cfs, or 0.13 cfs per square mile. The flow-duration curve
given in figure 17 has a greater slope than that for other streams in the
area and shows the flow of Jacks Branch to be more variable.
The low yield of Jacks Branch, as compared with other streams in the
area, is a result of unusually low base flow or seepage to the stream.
Only about 30 percent of the total runoff is base flow, whereas the base
flows of other streams comprise from 55 to 75 percent of the total. Direct
surface flow, or overland flow, of Jacks Branch is about the same as other
streams, based on a unit area comparison. The average annual runoff of
Jacks Branch is 14 inches.
Elevenmile Creek drains into the north end of Perdido Bay and is
used for industrial waste disposal.
Bayou Marcus Creek drains 25.9 square miles along the northwestern
outskirts of Pensacola and empties into the northeast corner of Perdido
Bay. Two years of records were collected at a gaging station located at
U.S. Highway 90 prior to construction of a dam in February 1960. The
dam created a reservoir of about 60 acres above State Road 296, about
two miles upstream from the gaging station.
An average annual flow of 43 cfs was measured at the gaging station
from a drainage area of 11.2 square miles. This unit runoff of 3.8 cfs per
square mile is the highest unit runoff within the two counties. The aver-
age runoff from this small area is about 50 inches per year, or 80 percent
of the average annual rainfall. This high runoff is probably derived from
large rates of ground-water inflow from areas outside the surface drain-
age divide.







REPORT OF INVESTIGATIONS No. 40


MINERAL CONTENT
The Perdido River and tributaries contain water of very good quality.
The highest mineral content of 52 ppm was recorded at Barrineau Park
where daily water samples were collected for one year. The mineral
content varies with streamflow. During high flows the mineral content
is lower because of dilution; however, during this same period the color
increases because of surface runoff. The color is the most objectionable
characteristic to potential industry because it is harmful to many proc-
esses and difficult to remove.
Elevenmile Creek contains the water of poorest quality in the two-
county area. Samples collected from Elevenmile Creek on a semiannual
basis have shown the mineral content to range from 392 to 914 ppm and
color from 500 to 1,250 units. This stream has been contaminated by in-
dustrial wastes; however, recent corrective measures have been taken to
clean it up.
On September 20, 1961, a chloride profile was made on Perdido
River. The salt front was followed with a specific conductance meter to
the point of furthest intrusion (see fig. 19). When the movement up-
stream of salt water halted a top to bottom profile was made at 2-foot
intervals. This was quickly followed by a series of profiles at various
points downstream.
On this particular day the salt extended a little over 63 miles up-
stream from the mouth. The flow of the river on this day is exceeded
about 50 percent of the time indicating the salt would probably extend
further upstream about 50 percent of the time.

ESCAMBIA RIVER BASIN
OCCURRENCE OF WATER
The Escambia River is the largest single source of surface water
within the study area and is the fifth largest source in the State. The
basin as outlined in figure 8 covers 4,233 square miles, of which 410
square miles are in Florida. The main channel starts near Union Springs,
Alabama, as the Conecuh River, and flows southwestward to the
Florida-Alabama line near Century, Florida. Near the State line the
name changes to Escambia River. The Escambia River flows southward
and empties into Escambia Bay north of Pensacola.
The average flow from the Escambia River basin is estimated to be
7,000 cfs. The average flow from the 410 square miles of the basin in
Florida is estimated to be 860 cfs. The average unit runoff at the Cen-
tury gaging station, drainage area 3,817 square miles. is 1.6 cfs per






FLORIDA GEOLOGICAL SURVEY


square mile. The average unit runoff from gaged tributaries in Florida
(Pine Barren Creek and Moore Creek) is 2.1 cfs per square mile.
The lower part of the Escambia River exerts a major influence on
the two-county area, not only because it serves as a source of water sup-
ply but also because of its size and location with respect to the fast de-
veloping industrial area around Pensacola. The lower basin is about 9
miles wide. The river channel is tortuous and winds through a low,
swampy flood plain about 3 miles wide. Several estuarine channels ex-
tend into the flood plain from Escambia Bay. Farther upstream two
islands within the flood plain are exposed during periods of low river
stages.
Flow in the lower river basin is affected by tide to a point north of
Brosnaham Island. The change in stage due to tide effect at the north
end of the island was 1.8 feet during a series of flow measurements
made on August 24, 1954, but the direction of flow does not reverse at
that point. A tide range of 2.5 feet is not uncommon near the nylon plant
of the Chemstrand Corporation. An observation of flow conditions made
near the Chemstrand plant on October 22, 1952, showed the flow to re-
verse at that point.
Soundings along the centerline of the lower channel, made by use of
a sonic depth-recorder, showed the deepest part of the channel to be
about 50 feet at a point 5 miles upstream from Escambia Bay. A depth-
profile graph made from these soundings is given in figure 23. Deep
holes in the channel, such as that 5 miles upstream from the river mouth,
trap salt water that can be a source of contamination of surrounding
ground-water supplies if heavy pumping from wells near the river is
carried on for long periods of time.
The tributaries below Pine Barren Creek are short and drain small
areas. The ridges forming the drainage divides vary in elevation from
150 to 200 feet above sea level. The Escambia River flood plain slopes
from about 15 feet above sea level near the mouth of Pine Barren Creek
to sea level at Escambia Bay.
The larger streams in the Escambia River basin with watersheds in
Florida are Pine Barren Creek, Canoe Creek, and Moore Creek.
Pine Barren Creek drains an area of 98.1 square miles, 85 square
miles of which is in Escambia County, Florida. The headwaters of the
creek are near the town of Atmore, Alabama, 2 miles north of the state
line. The average yield of Pine Barren Creek is 28.6 inches per year,
which is about 45 percent of the rainfall on the basin. A very substantial
base flow of 60 cfs (38.8 mgd) has been measured from the area of
75.3 square miles above the gaging station. The magnitude of flow will







REPORT OF INVESTIGATIONS No. 40


be different at any other point in the basin. Based on a flow measure-
ment of a tributary entering just below the gaging station, it is assumed
that the magnitude of flow at any point in the basin is proportional to
the size of the area drained above that point.
The average flow from the Pine Barren Creek basin is estimated to
be 207 cfs, of which about 28 cfs comes from Alabama and 179 cfs from
the drainage area within Escambia County, Florida. About two-thirds of
the total streamflow is base flow or seepage, and one-third is direct run-
off from overland flow.


Su.r m.d. by d~plh
ncordr Au9.22,1961


-250- Chloride t ont oA. 2219
--250-- Chloride oltean!. in parts per inmocl


Figure 23. Channel-bottom profile for lower Escambia River.

The length of the Perdido River basin is about six times the width.
This elongated shape and the steep topography of the basin produce a
short time of concentration of runoff. Rain anywhere on the basin has to-
move only a short distance before reaching the main channel. The steep.
valley slope of the main channel allows this water to flow at high veloci-
ties to the Escambia River. The channel-bottom profile of Pine Barren
Creek is given in figure 24. This channel has an average slope of more
than 10 feet per mile.
The fast-changing rates of flow during floods in this basin can be
visualized more clearly by comparing an average flow for a day with the
momentary peak flow. The mean daily flow for April 14, 1955, was 9,46(0







42 FLORIDA GEOLOGICAL SURVEY

cfs and the peak flow on the same day was 24,800 cfs-over 2% times
greater.
The flow-duration curve for Pine Barren Creek given in figure 15
shows the percent of time a specified discharge has been equaled or
exceeded. For example, the mean daily flows at the gaging station were


CHANNEL DISTANCE ABOVE SOUTH, IN MILES


Figure 24. Channel-bottom profile of Pine Barren Creek.


greater than 67 cfs (43 mgd) for 98 percent of the time. If an industry
needs a water supply of 43 mgd, a deficiency 2 percent of the time might
be tolerated if it were uniformly distributed, with only a few days of
deficient flow in any continuous period. A deficient flow of 2 percent of
the time, on the other hand, could prove disastrous if it came in a con-
tinuous period of several months duration.
The data given in figure 25 are helpful in determining probability
of length of periods of deficient flow. The lowest average flow for a
specified period can be determined from the lower curve in figure 25.


-00 -- --



,r -- -- -- -/- -
,I. _. ___ I __ -



S ___


S Spe.g5ophic map.

2) '
-f rr----


0o
2 4 10 12 14 as t 20 22 24 26


i








REPORT OF INVESTIGATIONS No. 40 43


For example, the lowest average flow for a 1-month period was 60 cfs
(38.8 mgd). The upper curve shows the longest period of time that a
specified flow was deficient. The curve shows, for example, the longest
period that the flow was 60 cfs or less was 10 consecutive days.
The curves shown in figure 25 can be used to determine if the flow


10,000
8000 -
6000
5000

4000 -
4000 Maximum period
2000 of deficient flow


1000
800 -
600 -
400
300

200


100
80
60
50

30 Lowest average flow
n for indicated period
20 -


S 2 23 568 1 24364872
1 2 3 4 6 8 10 20 1 2 3 4 56 8 12 18 24 36 48 72


CONSECUTIVE DAYS


CONSECUTIVE MONTHS


Figure 25. Discharge available without storage, Pine Barren Creek near Barth,
1952-61.


is sufficient for a particular use without storage. If storage is needed, the
amount of storage required can be determined from the mass-flow curve
given in figure 26. The volume of water required in a reservoir can be
determined by superimposing a line representing the required rate onto
the mass curve at such a position as to give the maximum distance be-
tween mass curve and the flow-required line. The maximum distance
represents the amount of storage required, excluding losses by evapora-
tion and seepage.








FLORIDA GEOLOGICAL SURVEY


20<


280



260



240


Storage required
12,000 cfs-doys


NOTE* No allowance mode for
evaporation and seepage
losses. |


0





0

Storage required
8500 cfs-days




0




0/



0

0






1952 1953 1954 1955 1956 1957 1958

Figure 26. Mass-flow curve for Pine Barren Creek near Barth, 1952-58.


18(



16<



14(



12(



10'






REPORT OF INVESTIGATIONS No. 40


The Moore Creek watershed covers 32 square miles in Santa Rosa
County. The flow from this creek enters the Escambia River just up-
stream from Pine Barren Creek. The yield from this basin is estimated to
be approximately the same as Pine Barren Creek basin, about 29 inches
per year. Average flow from the basin is estimated to be 67 cfs.
Canoe Creek lies mostly within Escambia County, Florida, with its
headwaters in Alabama-24 square miles in Florida and 13 square miles
in Alabama. The channel bed is lined with sand and gravel, and the
banks are steep and heavily wooded. Based on a field observation of the
physical characteristics of Canoe Creek basin, it appears that the flow
characteristics are similar to those of Pine Barren Creek. An average
flow of 78 cfs for Canoe Creek is obtained by multiplying the drainage
area by the unit runoff of 2.1 cfs per square mile for Pine Barren Creek.
The drainage area of the Escambia River at the Century gaging
station is 3,817 square miles. The river above the Century gaging station
is called the Conecuh River in Alabama. Its basin is slightly elongated
in shape, with the longer axis lying in a northeast-southwest direction.
The Conecuh River is located along the southern edge of the basin. All
of its large tributaries have their headwaters along the northern edge of
the basin and flow southward to the Conecuh River.
The seasonal distribution of flow at the Century gaging station, al-
though from a large area located in Alabama, follows a pattern similar
to that of the smaller nearby streams in Florida. The bar graph in figure
27 shows the seasonal distribution of flows for a 27-year period at the
gaging station at State Highway 4 near Century. The highest average
flows occur in March and April and the lowest flows occur in September,
October, and November. The variation 'of flows for any month can be
great. January has the greatest variation of monthly mean flows, varying
from a low of 1,900 cfs to a maximum of 31,500 cfs. October has the low-
est variation of monthly mean flows ranging from 666 cfs to 7,530 cfs.
Some streamflow characteristics for the 27-year period of record at
the Century gaging station are indicated by the flow-duration curve in
figure 17. Based on the flow-duration curve, the flow has been below
1,000 cfs (646 mgd) for only 3 percent of the time. The maximum flow
during the 27-year period ending in 1961 was 77,200 cfs, and the mini-
mum flow recorded was 600 cfs (388 mgd). The computed peak dis-
charge for the flood of March 1929 was 315,000 cfs. The elevation of this
flood peak was 66.1 feet above sea level which was 4.5 feet above the
floor of the bridge. Regional flood-frequency curves for the Escambia
River basin are given in figure 20.
The average yield per unit area from the Escambia River basin ap-


45








FLORIDA GEOLOGICAL SURVEY


I J I F I M I A I M I J I J A 1 S 1 0 1 N I D I

Figure 27. Graph of the minimum, average, and maximum monthly discharge of the
Escambia River near Century, 1935-61.


32.000


zoo







REPORT OF INVESTIGATIONS No. 40


pears to be about the same throughout the basin. Based on records of
the eight gaging stations that are located throughout the basin, the av-
erage yield is about 21 inches per year, ranging from a low of 18.3 inches
to a high of 28.7 inches. The flows measured at these stations came from
drainage areas ranging in size from 75.3 to 3,817 square miles. The
average yield at the Century gaging station was 21.9 inches per year.

MINERAL CONTENT
The Escambia River passes through the outcrop area of the Floridan
aquifer in southern Alabama and dissolves minerals from these lime-
stones. The water of the Escambia River near Century has a mineral
content ranging from 47 to 101 ppm. This is generally considered to be
low mineralization, but compared to the waters of other streams in
Escambia-Santa Rosa counties, it is high. This mineralization is diluted
by the flow from the tributaries that empty into the Escambia River. A
semiannual station located on the Escambia River near Quintette shows
a maximum dissolved solids of 60 ppm. The extent of the salt water
wedge in the tidal reach of the river is dependent on the flow of the
river and the height of the tide in Pensacola Bay. During periods of high
tides and low flows, the salt water extends upstream just beyond the
Chemstrand plant (see figs. 23, 28).
In the last 3 months of 1959 the flow in the Escambia River at Cen-
tury was high and as shown by the graph in figure 28 the chloride at the
Chemstrand plant was low. During the last 3 months of 1960 the situa-
tion was entirely different. The flow at Century was low and the chloride
at the Chemstrand plant was high. On November 22, 1960, the flow at
Century was 1,550 cfs (equaled or exceeded 90 percent of the time)
and the chloride at Chemstrand was 1,454 ppm. On August 22, 1961, a
chloride-profile run on the Escambia River (fig. 23) showed that the
salt front extended about 3& miles upstream. On this day the flow at
the Century gaging station was 2,380 cfs, (equaled or exceeded 70 per-
cent of the time).
The tributaries of the Escambia River originate in highland regions,
the major recharge areas for the sand-and-gravel aquifer. Surface water
in these tributaries is very low in mineral content and generally is very
clear. However, color increases due to contact with organic material
during periods of high flow.
Silica and color could be the two objectionable constituents in the
Escambia River. Silica ranges from 5 to 21 ppm and color ranges from
4 to 120 platinum-cobalt units. The quantity and quality of the waters of
the Escambia River basin make it a good potential source.









FLORIDA GEOLOGICAL SURVEY


1400 ------ 14000


FClw ---



S ,

1000 10000

S I : 0




4 0' I 0' 0 00
'
:0, ,
I








200 2000
.. i
P-


OCTOBER 1 NOVEMBER DECEMBER


2 z



12oo 0ooo
o I ,
2 100 10000





ur i E C t
W 800 .-













strand plant to streamflow at State Highway 4 near Century, October-December 1959
an600 October-D r 000
400 -0



zoo 2000



N 0 20 10 4 10 203 0
OCTOBER NOVEMBER DECEMBER

Figure 28. Relation of daily chloride content in water in Escambia River at Chem-
strand plant to streamflow at State Highway 4 near Century, October-December 1959
and October-December 1960.


10 23


D I0 20


I 10 20 3C






REPORT OF INVESTIGATIONS No. 40


BLACKWATER RIVER BASIN

OCCURRENCE OF WATER
Blackwater River heads in southern Alabama, north of Bradley. The
river enters Florida north of Baker, flows across the northwestern corner
of Okaloosa County, and winds southward along the Santa Rosa-Okaloosa
county line for a distance of about 4 miles. At Bryant Bridge at the
county line, the river turns to the southwest and is joined by Big Juniper
Creek and Big Coldwater Creek, and then continues toward Milton. At
Milton it turns southward and flows into Blackwater Bay.
The shape of the Blackwater River basin and the pattern of drainage
are similar to those of the Escambia River basin, in that the main chan-
nel parallels the eastern and southern edge of the basin and all major
tributaries enter from the north. The basin is well dissected by tortuous
stream channels that wind their way through a thick forest of pine and
juniper trees. Except during floods, the water is clear and flows in clean
channels of sand and gravel.
The following discussion of streamflow is by tributary basins, pro-
ceeding upstream in the following order: Pond Creek, Big Coldwater
Creek, Big Juniper Creek, and upper Blackwater River.
Pond Creek drains an area of 88 square miles, all within Santa Rosa
County. The creek flows southward and empties into the Blackwater
River just south of Milton. The basin has an elongated shape with rela-
tively short tributaries that drain directly from the steep hills. The land
along the basin divide is flat and is from 1 to 2 miles wide. From the
flat divide, however, the land slopes steeply to the stream channel.
Pond Creek has two channels within the lower three-fourths of its
flood plain. One of these is the natural channel which is very crooked
while the other is a straight channel dug many years ago for transporting
logs. The valley slope is steep (fig. 29) with a total fall of about 200 feet
from the headwaters to the mouth, a distance of 24 miles.
The estimated unit runoff from Pond Creek is 1.4 cfs per square mile,
which is equivalent to an average flow of 123 cfs from the basin. The
minimum daily flow measured at the gaging station during a 4-year
period ending 1961 was 43 cfs, or 0.7 cfs per square mile. About 75 per-
cent of the total flow is derived from the ground as base flow and 25
percent is direct runoff by overland flow.
Big Coldwater Creek is the largest tributary feeding the Blackwater
River. The total area drained by this tributary is 241 square miles, of
which 228 square miles are in Santa Rosa County. All except the smallest







FLORIDA GEOLOGICAL SURVEY


streams in the Big Coldwater Creek basin have perennial flows. The
average flow from the basin is estimated to be 542 cfs, of which 517 cfs
come from the drainage area within Santa Rosa County.
The unit runoff of East Fork and West Fork, the two main tributaries
of Big Coldwater Creek, is slightly lower than that of the main creek.
The unit runoff from the upper 64 square miles of East Fork is 2.0 cfs
per square mile; that from the upper 39.5 square miles of West Fork is
1.9 cfs per square mile; and that from the 237 square miles above State


75
s0
30


VALLEY DISTANCE ABOVE MOUTH,


IN MILES


Figure 29. Channel-bottom profile of Pond Creek.


Highway 191, below the confluence of the two forks, is 2.2 cfs per square
mile. The intervening drainage area of 133.5 square miles between the
two gaging stations on the forks and the gaging station on State High-
way 191 has a unit runoff of 2.5 cfs per square mile. About 60 percent
of the flow of West Fork Coldwater Creek is base flow and 40 percent
is direct runoff from overland flow.
Streamflow records have been collected for 23 years (1938-61) on
Big Coldwater Creek. The gaging station near Milton is located on State
Highway 191 and measures flow from 237 square miles. The flow-dura-


-1-- ----


02-4--62
0 2 4 6 a 10 12 14 is is 20 22 24 ef


3







REPORT OF INVESTIGATIONS NO. 40


tion curve for Big Coldwater Creek in figure 16 shows some streamflow
characteristics at this point. Because of the rolling topography and steep
slope of the basin, flood waters drain rapidly. Ground-water seepage
sustains the base flows at rather high rates during dry weather.
A useful arrangement of data is the group of low-flow frequency
curves given in figure 30. They show what the lowest daily flow is likely
to be and how often it is likely to occur. For example, the 1-day average
flow of 200 cfs (129 mgd) for Big Coldwater Creek has an average re-
currence interval of about 7 years.
The seasonal distribution of runoff in Big Coldwater Creek basin
follows very closely the pattern of rainfall. The distribution of monthly
flows is given in figure 31. Heavy spring rains cause high runoff, thus
March and April have the highest average flows. High-intensity rain-
storms in July and August cause high peak flows. October is the month
of lowest flow.
Big Juniper Creek, which joins the Blackwater River 5 miles up-
stream from Big Coldwater Creek, drains 146 square miles, of which 134
square miles are in Florida. The streambeds in this basin are composed
of loosely packed sand and gravel, and the banks are steep and heavily
wooded.
The average flow from the Big Juniper Creek basin is estimated to
be 260 cfs, or 1.8 cfs per square mile, of which about 240 cfs comes from
the area within Florida. Flow was measured at the three sites within the
basin: Big Juniper Creek at State Highway 4, near Munson; Sweetwater
Creek at State Highway 4, near Munson; and Big Juniper Creek near
Harold. Runoff characteristics are similar at these three sites. Slightly
over one-half of the flow is base flow; the remaining is direct runoff
from overland flow.
The Blackwater River drains 580 square miles in Santa Rosa County
and 280 square miles in surrounding areas. The streams in this basin
bring 390 cfs into the county from surrounding areas, pick up 1,100 cfs
within the county, and discharge an average of 1,490 cfs into Blackwater
Bay.
The main stem of Blackwater River brings in most of the flow from
outside the county. The average flow at the Santa Rosa-Okaloosa county
line near Holt is estimated to be 440 cfs. The flow-duration curve given
in figure 16 is based on records collected at State Highway 4 near Baker
in Okaloosa County. The drainage area above this point is 205 square
miles. The daily flow has varied at this site from a low of 61 cfs to a
high of 10,300 cfs. The average flow is 320 cfs. The flood of December








FLORIDA GEOLOGICAL SURVEY


LOW-FLOW FREQUENCY
Example: For a IO-year recurrence
interval the I-day minimum flow
is 213cfs and the 12-month
minimum flow is 513cfs


1.5 2 3 4 6 8 10 20 30


RECURRENCE


INTERVAL, IN YEARS


Figure 30. Low-flow frequency curves for Big Coldwater Creek near Milton, 1938-61.


1200




1100


600


500


300


200


105 LI






REPORT OF INVESTIGATIONS No. 40


2000


1800


1600


1400


1200


1000


800


600


400


200


I JI F M A IM J J J A S N IDI
Figure 31. Graph of minimum, average, and maximum monthly discharge of
Big Coldwater Creek near Milton, 1938-61.







FLORIDA GEOLOGICAL SURVEY


4, 1953, reached a crest elevation of 81.3 feet above sea level at State
Highway 4 and a peak flow of 17,200 cfs.
The lower 6 miles of the Blackwater River channel varies in depth
from 10 feet to as much as 60 feet in holes. A depth-profile graph is
given in figure 32. At least 6 holes in the lower river are 35 to 60 feet
deep_ These deep holes trap salt water moving in from the Gulf and
could be a source of contamination of the surrounding ground water if
large capacity wells are located nearby and pumped heavily enough to
cause major drawdowns. The salt front during extreme high tides ex-
tends upstream about 6 miles from Blackwater Bay.









S0 2 Mie


I -I I
o c


Figure 32. Channel bottom profile of lower Blackwater River.






REPORT OF INVESTIGATIONS No. 40


MINERAL CONTENT
The surface waters of this basin are of exceptionally good quality,
with a mineral content ranging from 11 to 33 ppm, and the water is
slightly acid (pH 5.5 to 5.9). The low mineralization of this water can
be attributed to its flowing through an area of practically insoluble sands
and gravels.
On September 2, 1961, a chloride-profile run on the Blackwater
River (fig. 32) showed that salt water extended about 59 miles up-
stream. Apparently, the downstream flow of the river causes the salt
water to be funneled in to Wright Basin, this being a course of least
resistance. Unless there was a very high tide accompanied by a low
flow, the salt water would probably not extend much farther upstream
than Wright Basin.

YELLOW RIVER BASIN
OCCURRENCE OF WATER
Yellow River heads in southern Alabama, north of Andalusia and
Opp. The river flows in a southerly direction, entering Okaloosa County
north of Crestview. South of Crestview, it is joined by Shoal River, its
largest tributary. The river then turns southwestward, enters Santa
Rosa County, and flows southwestward into Blackwater Bay.
The Yellow River drains 1,365 square miles, of which only 115 are
in Santa Rosa County. Although only a small percentage of the basin is
in Santa Rosa County, the entire flow of the river is available to the
county. The average flow entering Blackwater Bay from the Yellow
River basin is about 2,500 cfs. This is the second largest flow in the two-
county area; the flow of Escambia River is the largest. Tides from the
Gulf of Mexico affect the flow in a large part of the 19-mile reach of
channel in Santa Rosa County. The main channel winds through a
heavily wooded, swampy flood plain about 2 miles wide. Several estu-
arine channels extend into the flood plain from Blackwater Bay. From
the Okaloosa County line to the mouth, there are several cutoff channels
that leave the main channel and re-enter farther downstream.

MINERAL CONTENT
The water of this basin is low in mineral content (23 to 32 ppm),
but has color ranging from 10 to 80 units. This color, owing to the river
flowing through a swampy area, makes the water objectionable for
many uses. Other than the color, the water is of very good quality.






FLORIDA GEOLOGICAL SURVEY


GROUND WATER
PRINCIPLES OF OCCURRENCE
Ground water is the subsurface water in the zone of saturation, the
zone in which all pore spaces are filled with water under pressure greater
than atmospheric. Potable ground water in Escambia and Santa Rosa
counties is derived from precipitation. Part of the precipitation reaches
the zone of saturation to become ground water. Ground water in Escam-
bia and Santa Rosa counties moves laterally under the influence of
gravity from places of recharge toward places of discharge, such as wells,
springs, and surface-water bodies.
Ground water in Escambia and Santa Rosa counties occurs undei
both nonartesian and artesian conditions. Where it is not confined, its
surface is free to rise and fall, and the water is under nonartesian con-
ditions. The upper water surface is called the water table. Where the
water is confined in a permeable bed that is overlain by a less permeable
bed, so that its water surface is not free to rise and fall, it is under arte-
sian conditions and the upper water surface in wells is called the arte-
sian pressure surface. The term "artesian" is applied to ground water that
is confined and under sufficient pressure to rise above the top of the
permeable bed that contains it, though not necessarily to or above the
land surface. The height to which water will rise in an artesian well is
called the artesian pressure head.
An aquifer is a formation, group of formations, or part of a formation
-in the zone of saturation-that is permeable enough to transmit usable
quantities of water. Places where aquifers are replenished are called re-
charge areas, and places where water is lost from aquifers are called
discharge areas.

HYDROLOGIC PROPERTIES OF THE AQUIFERS
Ground water in Escambia and Santa Rosa counties occurs in three
major aquifers: a shallow aquifer which is both artesian and nonartesian
(the sand-and-gravel aquifer), and two deep artesian aquifers (the
upper and lower limestones of the Floridan aquifer). In the southern
half of the area, the sand-and-gravel aquifer and the upper limestone of
the Floridan aquifer are separated by a thick section of relatively im-
permeable clay; but in the northern half the sand-and-gravel aquifer and
the upper limestone of the Floridan aquifer are in contact with one an-
other. The upper limestone of the Floridan aquifer is separated from
the lower limestone by a thick clay bed.







REPORT OF INVESTIGATIONS No. 40


SAND-AND-GRAVEL AQUIFER
The sand-and-gravel aquifer is composed of sand but has numerous
lenses and layers of clay and gravel. In the northeast corner of Santa
Rosa County, the aquifer extends from the first saturated beds (near
land surface) to a depth of about 350 feet. In the center of the area,
however, it extends to a depth of about 1,000 feet. This aquifer lies at
the surface throughout Escambia and Santa Rosa counties.
The shallow saturated permeable beds in the sand-and-gravel aquifer
contain ground water under nonartesian conditions, and the deep perme-
able beds contain ground water under artesian pressure. The artesian
water is confined by lenses of clay and sandy clay. Most of the water in
the sand-and-gravel aquifer is under artesian pressure.
The gradient of the water table in the shallow beds of the sand-and-
gravel aquifer generally indicates movement of ground water toward
the nearby streams. The seepage of this ground water supplies more than
half of the entire flow of the smaller streams in Escambia and Santa Rosa
counties. The water table is the highest under the broad, relatively level
lands that are at a higher elevation than surrounding lands. Examples of
places where the water table is high include the lands between Jay and
Milton, the lands between Pensacola and Cantonment, and the land
east of Milton.
The artesian pressure head of water in the lower permeable beds of
the sand-and-gravel aquifer does not conform to the topography of the
land as much as the water table. The artesian pressure head of water
from the lower beds indicates a general movement of water to the south.
The head of water in the northern part of both counties is usually more
than 100 feet above sea level and at some places is more than 150 feet
above sea level. In the central part of the counties, the artesian pressure
head is about 30 to 80 feet above sea level except near the larger rivers.
Upward leakage of ground water probably occurs which lowers the
pressure head of the ground water. The artesian pressure head of water
under the lands adjacent to the bays is usually less than 20 feet above
sea level and often less than 10 feet above sea level.

FLORIDAN AQUIFER
In Escambia and Santa Rosa counties, the Floridan aquifer is com-
posed of two sections of limestone separated by a thick clay bed. In the
northeast corner of Santa Rosa County, the upper surface of the Floridan
aquifer is only about 350 feet below the land surface; whereas in the
southwest corner of Escambia County the upper surface is more than






FLORIDA GEOLOGICAL SURVEY


1,800 feet below the land surface, owing to the southwestward dip of the
aquifer.
The Floridan aquifer is thickest, 1,300 feet, in north-central Santa
Rosa County and thinnest, 800 feet, at the Perdido River near Perdido
Bay. The thickness of the Bucatunna Clay Member has not been in-
cluded in the above figures.
The water in the Floridan aquifer is under high artesian pressure.
The artesian pressure head in wells drilled into the upper limestone of
the FIoridan aquifer in southeastern Santa Rosa County is about 50 to
70 feet above sea level (fig. 33). At low land-surface elevations, 50 to
several hundred gallons per minute by natural flow are obtained from
this aquifer; but the water is more mineralized than that from the sand-
and-gravel aquifer. Because suitable water of low mineral content usu-
ally is available near the surface, little use is made of the water from the
upper limestone in this area.

MOVEMENT OF WATER
Ground water in the sand-and-gravel aquifer moves from high to low
elevations. Ground-water levels usually correlate with land-surface ele-
vations. Thus, in the two counties, the general areas of ground-water
recharge can be delineated on topographic maps. Recharge is greatest
where the land is relatively flat. Water percolates downward to the wa-
ter table and then moves laterally toward the places of discharge.
The lower permeable beds in the sand-and-gravel aquifer are re-
charged by percolation of water from upper permeable beds through
and around beds of clay or sandy clay. The percolation results from
differences in the hydrostatic heads within the permeable beds.
The sand-and-gravel aquifer is recharged by local rainfall, which in-
filtrates to the water table. The aquifer is discharged by pumping;
evapotranspiration; and seepage into streams, swamps, bays, and the
Gulf of Mexico.
Data at Gulf Breeze were used to calculate the amount of recharge
received by the upper part of the sand-and-gravel aquifer for different
periods of time. Gulf Breeze was selected because the surface material
contains little clay, the water table is near the surface, and the direct
overland runoff is slight. In addition, no lateral movement of fresh
ground water to or from other areas is possible because Gulf Breeze is
on a peninsula. Thus, recharge from rainfall at Gulf Breeze would be as
great as anywhere in the area.
The highest percentage of recharge from rainfall, about 92 percent,







REPORT OF INVESTIGATIONS No. 40


occurred from a one-day rain on October 10, 1959. The 7.5-inch rainfall
on this day (at Pensacola Beach) caused a rise in the water table of
2.54 feet by the next day, equivalent to 7.0 inches of water computed by
using a coefficient of storage of 0.23. The loss by evapotranspiration in
one day was estimated as 8 percent. Later that month on the 28th, a
rain of 4.15 inches caused a rise in the water table of 0.92 foot. On the
assumption that the coefficient of storage remains a uniform 0.23, this
rise accounts for about 61 percent of the rain. These short-term recharge
values were obtained by comparing the amount of ground water taken
into storage if all the rain percolated to the water table to the amount of
water actually taken into storage.
The average annual amount of recharge from rain may be computed
by determining the amount of rain that falls on an area and computing
the amount of seepage from that area. The average water level near the
center of the peninsula at Gulf Breeze is 4.5 feet above sea level. This
gives a hydraulic gradient of about 9 feet per mile toward Pensacola Bay
and toward Santa Rosa Sound. Using this gradient and the rate of move-
ment of water through the sand, the average ground-water seepage into
either Pensacola Bay or Santa Rosa Sound would be about 305,000 gpd
per mile length of the peninsula. The total seepage into Pensacola Bay
and Santa Rosa Sound would be about 610,000 gpd per mile length of
the peninsula. The average rainfall at Pensacola from 1950 through 1961
was 61.6 inches. The average rain falling on a one-mile length of the
peninsula (which is about 0.95 square mile) was about 2,770,000 gpd.
The average daily seepage of fresh ground water represents the annual
amount of recharge from rainfall and is about 22 percent of the total
rain or 13.6 inches of rain. The figures do not take into account the loss:
by pumpage of ground water and the loss by evapotranspiration after
the water reaches the water table. The amount of water removed by
these processes would increase the recharge to possibly 25 to 28 percent
or about 15 to 17 inches of rain.
A graph of monthly rainfall at Pensacola and graphs of the water
levels in an artesian well and in two nonartesian wells, drilled into the-
sand-and-gravel aquifer, are illustrated by figure 33. Wells 054-726-1
and 054-726-2 are at Oak Grove in northern Escambia County, and are-
about 6 feet apart. Well 055-726-1 is 0.6 mile north of these two wells.
Relatively permeable and impermeable beds and changes in water levels-
caused by rainfall are shown in figure 33.
Well 054-726-1 was drilled to a depth of 206 feet and is screened from
201 to 206 feet in a permeable sand bed. Although the top of the bed is
190 feet below the surface, the water in the well rose to within 83 to 90








60 FLORIDA GEOLOGICAL SURVEY


feet of the surface. The artesian pressure head ranged from 170 to 177

feet above sea level during the period of record. The artesian pressure

head rose about 3 feet from May 1959 to July 1960, then declined about
2 feet until February 1961. High rainfall periods in 1961 and 1962 caused

the head to rise more than 5 feet until April 1962. From April until


Werls _7














el 054-726,2 and
055-726-1.
Screen in

EXPLANATION

Relotvely permeable

Relatively impermeable

Sond

Cloy

Grovel
Screen n
well 054-726-1


Graphic
log



25


U50
WI


75










2CC
1-5





20(0


1959 1960 1961 1962

Figure :33. Water levels in an artesian well and two nonartesian wells drilled into the
sand-and-gravel aquifer in northern Escambia County, and graph of monthly rainfall
at Pensacola.



September 1962, the artesian pressure head declined about 2 feet be-

cause of below normal rainfall.
Well 054-726-2 was drilled to a depth of 107 feet and is screened

from 102-107 feet in a permeable sand bed. The water in this bed is not

under artesian pressure, and its upper surface is free to rise and fall. The
water level ranged from 184 to 194 feet above sea level during the period

of record. The water level rose several feet every spring or summer. Be-


186 176
j 8 -V I


- 17863--




Id 184 70
< 173





Well 055-726-I (Nooresion)
S/Depth 2049 feet
120
cr
169
16B
N-,- Wl 055-726-1(Noncriesion)
167 .
20
Totoli797inches Totol-677inches Totol -79 inches I Tol'427 inches
~3 tO I ~ I )~
:0







REPORT OF INVESTIGATIONS No. 40


cause the land around Oak Grove is cultivated, tilling the soil may in-
crease the amount of recharge from rainfall.
Well 055-726-1 was drilled to a depth of 80 feet and screened from
44 to 49 feet in a permeable sand bed (fig. 34). This sand bed is be-
lieved to be a continuation of the bed tapped by well 054-726-2. The


IpOO 0


1,000


I0
2POO


3,000


4,00O


DISTANCE, IN FEET FROM PINE BARREN CREEK
Figure 34. Cross section showing geology and hydrology in northern Escambia
County.

water in this bed is not under artesian pressure. The water level ranged
from 167 to 170 feet above sea level during the period of record. The
water level fluctuation in well 055-726-1 was similar to the fluctuation in
well 054-726-2, but much less. Well 054-726-2 is near the center of a
recharge area at Oak Grove and the water level in this well changed
about 10 feet. Well 055-726-1 is about 600 feet south of a discharge area,
Pine Barren Creek, and the water level in this well changed only about
3 feet. Water-level changes are usually much greater near areas of re-
charge than those near areas of discharge.


Note Well locations shown on figure 33
Cross section located 12miles west- southwest of
Century and along State Rood 99






FLORIDA GEOLOGICAL SURVEY


Figure 34 shows some geologic and hydrologic conditions in the Oak
Grove area. The beds of clay and sandy clay have been classed as rela-
tively impermeable beds. The beds of sand, sand and gravel, and gravel
have been classed as relatively permeable beds. In the vicinity of wells
054-726-1 and 2, ground water is recharged from local rainfall. Most of
this recharge moves northward and seeps into Pine Barren Creek. Some
of the recharge percolates downward to the lower permeable zone.
Ground water in this lower permeable zone may also seep into Pine
Barren Creek or move southward and discharge into other streams.
The water level in well 054-726-2 is generally from 14 to 18 feet
higher than the level in well 054-726-1. Thus, water in the upper perme-
able sands has the head potential to recharge the lower permeable sands.
The water level in the upper sands shows more response to high rainfall
than that in the lower sands.
The Floridan aquifer is recharged by rain in areas where the lime-
stones outcrop in Conecuh, Escambia, and Monroe counties, Alabama,
10 to 35 miles north of the area. The upper limestone of the Floridan
aquifer probably is recharged also by percolation from the sand-and-
gravel aquifer in the northern half of the area. The aquifer is discharged
by seepage into the Gulf, upward and downward leakage, and pumping.

GROUND-WATER VELOCITIES
The rate of ground-water flow depends upon the slope of the water
surface, the permeability of the aquifer, and the temperature of the
water. A knowledge of the rate of ground-water flow is useful to deter-
mine how fast and how far contaminated ground water will move, to
predict future areas of salt-water encroachment, and to evaluate the
effectiveness of clay beds as aquicludes.
Using the earliest water-level data available, Jacob and Cooper
(1940, p. 50-51) computed the average ground-water velocity in the
sands near Pensacola Bay to be 0.37 foot per day, or 135 feet per year.
The figure given represents the velocity under natural, undisturbed
conditions. In the vicinity of discharging wells, the velocities would, of
course, be higher.
The average velocity of ground water moving through an aquifer
may be computed by the following formula:

Tg
V=-
7.48 mp
Where: V is the velocity in feet per day; T is the coefficient of trans-
missibility in gpd (gallons per day) per foot; g is the gradient of the







REPORT OF INVESTIGATIONS No. 40


water table in feet per mile; m is the thickness of the aquifer in feet; and
p is the porosity of the aquifer in percent.
Data from Gulf Breeze was used to compute the highest, average,
and lowest velocities of the water in the upper part of the sand-and-
gravel aquifer. In 1959, the water level at Gulf Breeze was 9.8 feet above
sea level, the highest level during the last 13 years. This level would
give an average gradient of 23 feet per mile (or 0.0044) toward Pensa-
cola Bay. The coefficient of transmissibility averages about 34,000 gpd
per foot and the aquifer is 80 feet thick. The porosity is assumed to be
about 30 percent. These figures give the highest velocity of ground water
in Gulf Breeze from the center of the peninsula toward Pensacola Bay of:
(34,000) (0.0044)
V (34,) (0.0044) = 0.83 foot per day,
(7.48)(80)(0.30)
or about 300 feet per year.
An inspection of the hydrograph at Gulf Breeze (fig. 38) gives an
average water level of 4.5 feet above sea level. Using this level, the av-
erage velocity of ground water is computed to be 0.38 foot per day or
about 140 feet per year. The lowest water level, 2.8 feet above sea level
(except when the water level was lowered by nearby pumping), oc-
curred in 1951. Using these data, the lowest velocity of ground water is
computed to be 0.24 foot per day or about 90 feet per year.

AREAS OF ARTESIAN FLOW
Water will flow from artesian wells when the artesian pressure head
is higher than the land surface. The water from rainfall percolates into
the ground in the higher, relatively level land and moves downward and
laterally toward places of discharge. Some of this water is confined by
impermeable beds below which the water is under artesian pressure.
The areas of flow of water from the sand-and-gravel aquifer in the
two counties are usually low lands along streams. One area of artesian
flow is at Molino, near the Escambia River, where the artesian pressure
head is more than 20 feet above the land surface in places. At Pine
Barren, the artesian pressure head is as much as 30 feet above the land
surface.
Water from the upper limestone of the Floridan aquifer is under
sufficient artesian pressure to rise to more than 50 feet above sea level
in the southeastern part of the area. Thus, the areas of flow from wells
that tap the Floridan aquifer are generally at elevations less than 50 feet
above sea level. Examples of areas of artesian flow of water from the
Floridan aquifer are at Gulf Breeze Peninsula, Holley, Navarre, Navarre






FLORIDA GEOLOGICAL SURVEY


Beach, Pensacola Beach, and the western two-thirds of Santa Rosa
Island.
Ihe artesian pressure head of water from the Floridan aquifer ranges
from about 140 feet above sea level in northern Santa Rosa County (well
059-658-1) to about 55 feet above sea level in southern Santa Rosa
County (well 022-652-1). Therefore, the artesian pressure head in the
Floridan aquifer would be greater than the water table in the sand-and-
gravel aquifer at most of the low to moderate land elevations in the two
counties. The water in the Floridan aquifer would have a potential up-
ward flow. The water level in the sand-and-gravel aquifer would stand
above the artesian pressure head of the Floridan aquifer in the higher
land elevations of the area and would have a potential downward flow.

FLUCTUATION OF THE WATER LEVEL
Water-level records show that the water surface is not stationary but
fluctuates almost continuously. Water-level fluctuations result from vari-
ations in recharge and discharge. Discharge is from evaporation and
transpiration, seepage, and pumping. Recharge is from rainfall and
seepage from other aquifers. Long-term periodic measurements of water
levels are used to determine significant changes in the water in storage,
to correlate water levels and rainfall, and to show the influence of pump-
ing on the water level. Long-term records are needed to distinguish
between short-term fluctuations and progressive trends.
Over most of the area, changes in the water level correlate in general
with rainfall. In the heavily pumped areas, water levels reflect both the
influence of the pumping and the rainfall.
Figure 35 compares changes in the artesian pressure head in a well
drilled into the Floridan aquifer with changes of the water level in a
well drilled into the sand-and-gravel aquifer. Well 037-645-1 is at Aux-
iliary Field 6, located 18 miles east of Milton, in Okaloosa County. This
well is 690 feet deep and obtains water from the upper limestone of the
Floridan aquifer from 527 to 690 feet below land surface. Well 032-648-1,
15 miles southeast of Milton, is 197 feet deep and obtains water from the
sand-and gravel aquifer from about 140 to 197 feet below land surface.
Well 037-645-1 is a representative well for this area. It taps the upper
limestone of the Floridan aquifer and has a long-term record. The hy-
drograph is included to show the relation between artesian pressure
changes and the use of water, to illustrate the fluctuations in artesian
pressure in the upper limestone of the Floridan aquifer, and to compare
these fluctuations with those in the sand-and-gravel aquifer.







REPORT OF INVESTIGATIONS No. 40


The hydrograph for the shallow well shows the water-level changes
during the last 15 years in an area where there is not much withdrawal
of ground water. When compared to rainfall records, the graph shows a
general correlation with rainfall and reflects a very wet period from
1944-49, a relatively dry period from 1950-55, a wet period from

90 I I I i- i- i i I- I- -I -
Well 037-645-1, 18 miles east of
Milton (in the upper limestone of the
Floridon aquifer') Depth 690 feet.



85



,.-,

80 -7
75 ____-






0 5 10 15 miles

= Well 032-648-1, 15 miles southeast of
S55 Milton (in the sand and grovel
Soaquifer) Depth 197 feet.




50 4 A .






Figure 35. Hydrographs of wells 037-645-1 and 032-648-1.

1956-61, and another dry year in 1962. The effect of 90.41 inches of
rainfall in 1953, the highest recorded in 83 years at Pensacola, is shown
by the rise in water levels during 1953 and the first part of 1954. How-
ever, this trend in the water level was reversed by the effect of the low-
est rainfall on record, 28.68 inches, in 1954. Declining water levels dur-
ing 1954 and the first half of 1955 reflect this low rainfall. The maximum






FLORIDA GEOLOGICAL SURVEY


change observed during the period of record was 13 feet. The water
level was highest, 56 feet above sea level, in 1949, and lowest, 43 feet
above sea level in 1955.
The hydrograph for well 037-645-1, which penetrates the upper lime-
stone of the Floridan aquifer, shows very different fluctuations. The
hydrograph shows a progressive decline in the artesian pressure head of
21 feet during the period of record. Artesian pressure was highest, 88
feet above sea level, in 1948 and lowest, 67 feet above sea level, in 1962.
The artesian pressure head stood above the water level in the sand-and-
gravel aquifer during the entire period of record.
The hydrograph for well 037-645-1 shows the decline of the artesian
pressure head that has occurred in the upper limestone of the Floridan
aquifer, in the Fort Walton Beach area. Barraclough and Marsh (1962)
found this decline to be greatest at Fort Walton Beach, about 17 miles
to the southeast, where one well had a decline of about 56 feet between
1948 and 1960, and a net decline of 125 feet between 1936 and 1962.
The amount of decline increases toward Fort Walton Beach and results
from use of water by Fort Walton Beach, Eglin Air Force Base, and
others. In addition, the decline relates to thinning of the upper limestone
northward from about 400 to about 40 to 60 feet thick. This thinning has
a restricting effect on the amount of water moving through the aquifer.
Barraclough and Marsh (1962) noted the large amount of clay in the
aquifer, both in beds and clay-filled voids, and suggested that the clay
within the aquifer reduces both the permeability and effective porosity
of the aquifer, resulting in the large drawdowns.
The artesian pressure head in well 037-645-1 has declined at an av-
erage rate of 1.4 feet per year. Wells that tap the upper limestone of the
Floridan aquifer in southeastern Santa Rosa County around Navarre
probably have had a similar rate of decline which may continue. Farther
away from the Fort Walton Beach, the artesian pressure heads have de-
clined at a slower rate.
Figure 36 contrasts changes of the water level in an area affected
slightly by pumping, as shown by well 031-716-1 at Ensley, with changes
of the water level in areas of heavy pumping, as shown by well 036-719-1
at Cantonment and well 036-716-1, 3 miles east of Cantonment. All three
wells are in the sand-and-gravel aquifer. From 1940 to 1962, the water
level at Ensley varied a maximum of 26 feet; the water-level high of 75
feet above sea level was recorded in 1948, and the water-level low of
49 feet was recorded in 1956. Well 031-716-1 is 239 feet deep. The rise
and fall of the water table in this area, as shown by the graph, closely
follows variations in rainfall. In general, whenever the annual rainfall









REPORT OF INVESTIGATIONS No. 40


50


60--




50 -





40
036-719-I,
at Cantonment
Depth 152 feet

30


I I I I


Conlonment SANTA ROSA
CO.
-".036-7t6-,
036-719-1
N

Ensley
031-716-1
SCAMBIA C O.
Pensacolo


0 2 4 6 8 10 miles




-NORMAL--
100-
Un
1: 80-

z


'0

< 20
1| 1////,"Y


EXPLANATION


Continuous record

Periodic record


20





10

036-716-1, 3 miles
W east of Cantonment
Depth 352 feet
i -- l I l- I i -- -- -


Figure 36. Hydrographs of wells 031-716-1, 036-719-1, and 036-716-1 and graph of
yearly rainfall at Pensacola.


-o
w
w





'0
w





2
Ui


w


. ,






FLORIDA GEOLOGICAL SURVEY


was less than 60 inches, the water level declined; and whenever the
annual rainfall exceeded 60 inches, the water level rose.
The water level in well 031-716-1 was about 10 feet lower in 1959-60
than in 1948-49 (fig. 36). The graph of well 032-648-1 (fig. 35) shows
a high water level in 1948-49 and a similar high water level in 1959-60.
Industrial pumping at St. Regis, 7 miles north-northeast of well 031-716-1
is believed to be the principal factor limiting the rise of the water level
in 1959-60.
Figure 36 shows the water level in- well 036-719-1 (152 feet deep) at
Cantonment. This hydrograph shows the decline usually associated with
continued, concentrated pumping in an area. During 23 years of record,
the water level fluctuated 42 feet. The highest water level was 65 feet
above sea level in 1941 and the lowest was 23 feet above sea level in
1957. The slight rise and then gentle decline of water levels for 1946-49
shows the effect of abnormally high rainfall.
The sharp decline of the water level in well 036-719-1 stopped in
1956. Late in 1958 the water level started to recover. This recovery was
the result of the following: (1) several nearby wells were taken out of
service; (2) rainfall was above normal in 1956 and 1958-61; (3) a re-
charge experiment was conducted by St. Regis Paper Company; and
(4) the use of cooling towers that began in 1961 lowered the pumping
rate. During this recharge experiment cooling water was pumped into a
nearby well at a rate of a million gallons per day for a year. The recharge
well is located 2,170 feet from well 036-719-1 and the calculated time-
distance-recovery curves indicate that this amount of recharge would
cause the nonpumping water level in well 036-719-1 to rise from 1 to
2 feet.
The hydrograph of well 036-716-1, about 3 miles east of Cantonment
and about 1 mile west-northwest of the Chemstrand Corporation plant,
is shown in figure 34. This well is 352 feet deep and is screened from
260 to 270 feet and from 340 to 350 feet below the land surface. The
water level is affected by pumping at two nearby industrial plants, the
St. Regis Paper Company and the Chemstrand Corporation. The graph
shows a maximum change of 16 feet during the 11 years of record, with
the highest water level being 24 feet above sea level in 1951 and the
lowest water level being 8 feet above sea level in 1959. The water level
declined rapidly from 1951 to 1957 owing to pumping and below-normal
rainfall. The water level was nearly stable during 1958 and recovered
about 3 feet from 1959 to 1962 owing to above-normal rainfall, infiltra-
tion of water from the Escambia River into the well field of the Chem-
strand Corporation, and reduced pumpage at St. Regis and Chemstrand.








REPORT OF INVESTIGATIONS No. 40


Figure 37 shows the water levels southwest of Pensacola, as recorded
in three wells. Two of the wells, 024-715-1 and 024-715-2, are near the
Newport Industries plant at Pensacola. Well 023-716-2 is in Warrington,
about 2 miles southwest of the plant. Well 024-715-1 is 142 feet deep and
is at Pensacola, 450 feet from Bayou Chico. The range of water-level
fluctuations in this well was 18.6 feet during the 23 years of record. The
water level was highest, 7.8 feet above sea level, in 1949 and lowest,
10.8 feet below sea level, in 1955. The water level in well 024-715-1 is


6 -- I i i I I i i I I
024-715-2,( beside024-715-1)
Depth 17.5 feet.



o "


Figure 37. Hydrographs of wells 024-715-1, 024-715-2, and 023-716-2.


I I I I I






FLORIDA GEOLOGICAL SURVEY


influenced by heavy pumping at Newport Industries and by changes in
rainfall. The water level was lowered by pumping before water-level
measurements were started in 1940.
Ground-water pumping at Newport Industries started in 1918 at an
average rate of 2 mgd and increased to an average rate of 9 mgd in
1939. Cooling towers were installed in 1941, 1948, 1954, and 1962. Re-use
of some of the water reduced the average pumping rate to 3.6 mgd in
1962.
The hydrograph of well 024-715-1 shows that the water level has
been lowered by heavy pumping by Newport Industries and has been
below sea level most of the time since the summer of 1952. As salt water
in Bayou Chico is only 450 feet from the well, the lowered fresh-water
levels could cause salty water from the bayou to percolate into the aqui-
fer in this area and destroy its usefulness.
Well 024-715-2, which was drilled beside well 024-715-1, is 17.5 feet
deep. The water level in well 024-715-2 had a range of only 4.4 feet dur-
ing the 23-year period of record. The water level rose to 5.2 feet above
sea level in 1956 and declined to 0.8 feet above sea level in 1951, 1955,
1957, 1958, and 1962.
The water level in shallow well 024-715-2 has been above the water
level in deep well 024-715-1 for most of the 23 years of record. The
greater head of water in the upper permeable beds permits some re-
charge to the lower permeable beds. However, some of the water from
the shallow zone moves laterally into Bayou Chico.
The hydrograph of well 023-716-2 (247 feet deep) at Warrington
shows that the highest water level was 6 feet above sea level in 1940,
and the lowest was 4 feet below sea level in 1952. The graph shows a
slight decline of the water level during the 23-year period, 1940-62,
owing to increased use of ground water in the Warrington area. During
the summers of 1943-45, 1950-58, and 1960-62, 15 of the 23 years of rec-
ord, the water level declined below sea level. The lowering of the water
during the summer is brought about by an increase in the use of ground
water.
The water level in well 021-709-8, half a mile east of the Gulf Breeze
post office, is shown in figure 38. This well was drilled to a depth of 41
feet and the lower 10 feet of the well was screened. During the 13-year
period of record, the water level fluctuated 8.6 feet. The highest water
level was 9.8 feet above sea level in 1959, and the lowest was 1.2 feet
above sea level in 1955.
Fresh ground water on Gulf Breeze Peninsula is derived entirely from
local rainfall. Some of the rain water percolates quickly through the










REPORT OF INVESTIGATIONS No. 40


I10 I I i i
> Well 021-709-8










1950 1955 1959 1962 Si

J Waler level affected Beezd
I- by nearby pumping peninsula
Z PERIODS OF RAINFALL
1. DRY < WET- DRY -
LL


W
-J
Ir
I
1-


ti


zj
I-I

wi


-I


Well 021-709-8


6

4
JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC
1959
16

14
RAINFALL AT PENSACOLA __ RAIFALL TOTAL
12 1959 TOTAL= 79.67 INCHES SEPT OCT
2 /29.6 INCHES /
io


















Well 021-709-B8
______ -__ _y_///,_ /.__ ,, __" __/__
6













1954 TOTAL 7 728.68 INHES
JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC
1959


-<

" Well 021-709-8






JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC
1954
- RAINFALL AT PENSACOLA _
l' 1954 TOTAL =28.68 INCHES




<4




JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC


1954

Figure 38. Hydrograph of well 021-709-8 and graph of the rainfall at Pensacola.






FLORIDA GEOLOGICAL SURVEY


few feet of sand to the water table. Ground water then moves laterally
and discharges into Pensacola Bay or Santa Rosa Sound. The water in
the upper part of the sand-and-gravel aquifer is under nonartesian con-
ditions, and the water level rises rapidly after intense rainfall and de-
clines slowly during prolonged periods without rain. The hydrograph of
well 021-709-8 shows the response of the water level to rainfall. Pump-
ing from nearby wells also had an influence on the water level in this
well. Wells owned by the Santa Rosa Island Authority were pumped at
rates of about 60,000 gpd during the winter and about 120,000 gpd dur-
ing the summer from 1951 to 1956. After 1956, when the pumping from
these wells ceased and rainfall was above average, the water level rose
gradually to a record high in 1959. From the high water level in late
1959 to mid 1962, the water level declined about 6 feet.
The hydrograph of water levels in well 021-709-8 and the monthly
rainfall at Pensacola for 1959 shows the rapid rise of the water level that
resulted from intense rainfall. The water level changed only slightly
until heavy rains in September caused a rise of 2.5 feet. Additional heavy
rains in October caused rises totaling about 4 feet. A total of almost 30
inches of rain fell in Pensacola in September and October 1959. These
rises brought the water table near or above the land surface in some areas
around Gulf Breeze, causing some damage and considerable incon-
venience.
The 1954 hydrograph in figure 38 illustrates a decline of the water
level during a year of low rainfall. In 1954, Pensacola had the lowest
rainfall of record, 28.68 inches. The water level at Gulf Breeze declined
6.2 feet during this year. The water level declined 5.7 feet from January
to September and remained less than 2 feet above sea level until the
end of the year. The ground-water table received very little recharge
from rainfall in 1954. Most of the rain was lost through evapotranspira-
ion.

TEMPERATURE OF GROUND WATER
The temperature of the earth's crust increases with depth at the rate
of about 10F. for each 50 to 100 feet. The temperature of ground water
generally increases with depth at approximately the same rate.
Ground-water temperatures in Escambia and Santa Rosa counties
from the sand-and-gravel aquifer 50 to 250 feet deep usually range from
66' to 730F. These temperatures reflect the average annual air tempera-
ture (680) at Pensacola and the geothermal gradient.
The temperature of water from the upper limestone of the Floridan






REPORT OF INVESTIGATIONS No. 40


aquifer in southern Escambia and Santa Rosa counties ranges from 840
to 920F. The wells that tap this aquifer are from 900 to 1,500 feet deep.
The temperature of ground water in this area usually increases about
1F. for each 52 to 85 feet of depth. For example, the geothermal gra-
dient 9 miles southwest of Pensacola, as shown by measurements made
in an oil test hole, is about l0. for each 81 feet of depth down to 12,500
feet. The temperature at the bottom of the hole was 2220F.

SPECIFIC CAPACITY
The specific capacity is used to indicate the amount of water, in
gallons per minute, that can be obtained from a well for each foot of
drawdown of water level in the well. The specific capacity is obtained
by dividing the yield of the well in gallons per minute by the difference
of the static water level and the pumping water level in feet. Factors
that affect the yield of wells include: (1) the diameter of the well;
(2) depth of aquifer penetrated; (3) transmissibility of the aquifer;
(4) efficiency of the pump; (5) amount of well development; (6)
amount and size of well screen (if any); and (7) the friction loss
within the well.
An example of the specific capacity of wells drilled into the sand-
and-gravel aquifer can be shown by data from 8 wells at the Chemstrand
Corporation nylon plant. The wells are constructed similarly with 24-
inch casing at the surface, 16-inch casing in the middle, and 12-inch
screen at the bottom. The amount of well screen is usually 110 feet and
the wells are pumped at 1,500 gpm for 24 hours. The specific capacity
ranged from 39.5 to 76.8 gpm per foot of drawdown and the average
specific capacity was 53 gpm per foot of drawdown.
Little information is known about the specific capacity of wells from
the Floridan aquifer in the area of study. However, large-capacity wells,.
10 to 16 inches in diameter, drilled into the Floridan aquifer in southern
Okaloosa and Walton counties had a specific capacity ranging from 10 to
100 gpm per foot of drawdown. The average specific capacity was 88
gpm per foot of drawdown. Similar values could be expected from wells
drilled into the Floridan aquifer in Escambia and Santa Rosa counties.

QUANTITATIVE STUDIES
The withdrawal of water from an aquifer creates a depression in the
water table or artesian pressure surface around the point of withdrawal.
This depression generally has the form of a cone with its apex down
and is referred to as the cone of depression. The amount by which the






FLORIDA GEOLOGICAL SURVEY


water surface is lowered at any point within this cone is known as the
drawdown. The size, shape, and rate of growth of the cone of depression
depend on several factors: (1) the rate of pumping; (2) the duration of
pumping; (3) the water-transmitting and storage capacities of the aqui-
fer; (4) the increase in recharge resulting from the lowering of the
water surface; (5) the decrease in natural discharge from the aquifer
due to the lowering of that surface; and (6) the hydrologic boundaries
of the aquifer.
A measure of the capacity of an aquifer to transmit water is the co-
efficient of transmissibility. This is the quantity of water in gpd (gallons
per day), that will move through a vertical section of the aquifer 1 foot
wide and extending the full saturated height of the aquifer, under a unit
hydraulic gradient, at the prevailing temperature of the water.
The coefficient of storage is a measure of the capacity of an aquifer to
store water. It is defined as the volume of water released from or taken
into storage per unit surface area of the aquifer per unit change in the
component of head normal to that surface.
The amount of water that may be stored in a rock or soil is limited by
the porosity of the material. The amount of water that a saturated rock
will yield when allowed to drain is somewhat less than the porosity
because some of the stored water will be held by capillarity.
The amount of water stored by an aquifer also depends on whether
the aquifer is artesian or nonartesian, for all aquifers serve as both con-
duits and reservoirs. An artesian aquifer functions primarily as a conduit,
transmitting water from places of recharge to places of discharge; how-
ever, it is capable of storing water by expansion, or releasing water by
compression. An artesian aquifer also stores water in the unconfined por-
tion of the aquifer. A nonartesian aquifer functions primarily as a reser-
voir and can store a much larger quantity of water for a given rise
in the water level than can be stored in an artesian aquifer.
The coefficient of transmissibility and coefficient of storage are gen-
erallv determined by means of an aquifer test on wells. Although only a
few aquifer tests have been made during the current investigation, many
detailed tests have been made in parts of the area. The coefficients deter-
mined by these tests are still applicable to the test areas and may be
used for hydrologically similar areas.
In the spring of 1940, Jacob and Cooper (1940, p. 33-49) made sev-
eral aquifer tests on wells owned by the City of Pensacola, the U.S. Navy
(at Corry Field), and Newport Industries. These wells were drilled
about 240 feet into the sand-and-gravel aquifer, and the lower half was
screened. The average coefficient of transmissibility, T, for 120 feet of






REPORT OF INVESTIGATIONS No. 40


aquifer, as determined by the tests is 75,000 gpd per foot. The coefficient
ranged from 58,800 to 94,000 gpd per foot. This coefficient may be used
to calculate the effects of pumping on the water level near Pensacola.
The average coefficient of storage is 0.00055. This relatively low average
coefficient of storage indicates that an effective confining layer overlies
the sands from which the water is withdrawn. However, this confining
layer does not extend over a large area.
The aquifer tests show that artesian conditions existed during the few
clays of the tests and perhaps artesian conditions would exist for as long
as a few weeks after continuous pumping started. Later, local recharge
by leakage from other parts of the sand-and-gravel aquifer would prob-
ably occur at the edges of and through the confining layers. This local
recharge would lessen the drawdown. Because of the effect of this re-
charge, it has been found by trial and error that reasonably accurate
drawdowns can be predicted using a storage coefficient of 0.15 in this
area. This coefficient of storage would give more reasonable time-distance-
drawdown figures than those calculated by using the average coefficient
obtained from the relatively short pumping tests. Jacob and Cooper
(1940, p. 48) calculated the "apparent coefficient of storage" to be 0.32 in
the upper sands in the Pensacola area. This calculated coefficient of
storage takes into consideration the effects of local recharge.
In the fall of 1950, Heath and Clark (1951, p. 31-34) made an aquifer
test on the Gulf Breeze Peninsula in Santa Rosa County. The test area was
about half a mile east of the Gulf Breeze post office. The wells pene-
trated the upper part of the sand-and-gravel aquifer and the coefficients
that were determined apply to the upper 75 feet of the aquifer. This
part of the aquifer was found to have a coefficient of transmissibility of
84,000 gpd per foot and a coefficient of storage of 0.23. This relatively
high storage coefficient indicates nonartesian conditions. Several curves
relating pumping rates and well spacing to the resultant drawdowns are
given in the report.
Several aquifer tests have been made during 1951-55 on some of the
Chemstrand Corporation's wells, about 13 miles north of Pensacola. Each
supply well is equipped with 110 feet of well screen, usually made up in
two sections. The screens are set in the most permeable zones in the sand-
and-gravel aquifer, between 170 and 380 feet below the sand surface.
The average value of the coefficients of transmissibility and storage de-
termined from these tests were about 150,000 gpd per foot and about
0.001, respectively.
The coefficients of transmissibility and storage may differ consid-
erably from place to place; therefore, drawdowns at one place cannot







FLORIDA GEOLOGICAL SURVEY


be predicted on the basis of data collected elsewhere. Figure 39 illus-
trates how water levels are affected in the vicinity of a pumped well
near the Chemstrand plant. This figure shows theoretical drawdowns in
the vicinity of a well pumped at the rate of 700 gpm (about 1 mgd)
from an aquifer having a transmissibility coefficient of 150,000 gpd per
foot and a storage coefficient of 0.15. As the drawdowns outside the
pumped well vary directly with discharge, drawdowns for greater or


DISTANCE. IN FEET. FROM PUMPED WELL
100 1,000

------ I 7


S.. .. .... Computed on the bosis of:
ST rSO150,000 gpd/ft
;0 '5 015
Q 700 gpm i
Note Compulolaons based on pumpig from storage from on
1Logqufer of lorge orel extent

Figure 39. Graph showing theoretical drawdowns in the vicinity of a well.

lesser rates of discharge may be computed from these curves. For ex-
ample. as shown in figure 39, under the assumed conditions, the draw-
down 100 feet from a well discharging at 700 gpm would be 4.3 feet after
100 days of pumping. If the well had discharged 2,100 gpm for the same
length of time, the drawdown at the same distance would have been
three times as much, or 12.9 feet.

MINERAL CONTENT
THE SAND-AND-GRAVEL AQUIFER
The sand-and-gravel aquifer is the major source of ground water used
in Escambia and Santa Rosa counties. Differences in the composition of
the aquifer affect the chemical quality of the water. In some areas clay







REPORT OF INVESTIGATIONS No. 40


lenses likely cause ionic exchange, resulting in water of altered mineral
content, and the solution of fossil shells in some formations probably con-
tribute to the mineralization. The general area of recharge is outlined in
figure 40 by the low sums of the mineral constituents in parts per mil-
lion. The low mineral content in the recharge area may be due to the
short time of contact between the water and the sand, gravel, and clay.
As the water moves into the aquifer and down and away from the re-
charge area, this mineralization increases. Inset "A" in figure 40 shows


Figure 40. Map of Escambia and Santa Rosa counties showing mineral content of
water from the sand-and-gravel aquifer.








FLORIDA GEOLOGICAL SURVEY


mineral content of water from deep wells in the sand-and-gravel aquifer.
Except for a few areas, the sum of mineral constituents in the water
of this aquifer is very low (12-36 ppm) throughout the two counties.
Figure 41 shows the type of ground water based on the major constitu-
ents in solution, regardless of total concentration. All elements are di-
vided roughly into two groups, metal and non-metals. In solution the
metals calcium, magnesium, sodium, and potassium are positively
charged cationss) and the non-metals carbonate, sulfate, chloride, fluo-


Figure 41. Map showing types of water from wells in the sand-and-gravel aquifer.







REPORT OF INVESTIGATIONS No. 40


ride, and nitrate are negatively charged anionss). Chloride-type water is
indicated by chloride as the major anion and is generally accompanied
by a predominant sodium cation. Carbonate-type water is based on car-
bonate as the major anion and calcium, magnesium, and sodium, either
singularly or in various combinations, being the major cations.
Intermediate-type water is characterized by carbonate and chloride
being almost equal and usually shows no predominance in the cations.
The chemical quality of the water from two wells located at Fort
Pickens State Park on the west end of Santa Rosa Island is distinctive.
They are the only two wells on Santa Rosa Island producing any quantity
of fresh water from the sand-and-gravel aquifer. The analysis of the wa-
ter from these two wells suggests the presence of a slight amount of
sea water. Sodium and chloride are among major ions present and the
magnesium exceeds the calcium, which is indicative of sea water. The
water has a pH slightly above neutral and a carbonate of 95 ppm, high
for this area. These two factors could be attributed to the action of the
usually acid water on fossil shells. This water is thought to cross under
the bay from the Pensacola area, separated from the salt water in Pensa-
cola Bay by an impermeable clay bed. The long exposure to clay could
account for the presence of high silica (20 ppm).
On Fair Point Peninsula, Heath and Clark (1951) found two aquifers
in the sand-and-gravel aquifer. The upper aquifer contains the more acid
water (pH 5.2 to 5.9) which has sodium and chloride for the major con-
stituents and is low in total mineralization. Water from the lower, more
fossiliferous aquifer contains carbonate as the major constituent and has a
pH of 7.2. A shallow well at Gulf Beach and a deeper well at Navarre
show chemical characteristics similar to the deep well at Fair Point,
whereas water from a shallow well at Santa Rosa Shores resembles the
water from wells in the upper aquifer at Fair Point. Water from the
sand-and-gravel aquifer in the southeastern part of Santa Rosa County
away from the coast has a very low mineral content and shows no pre-
dominant chemical constituents.
In the section of Pensacola bordering closely on the bays, the water
from this aquifer is generally very low in mineral content but shows a
predominance of sodium and chloride ions. This slight salt-water en-
croachment could be due to pumping in the area. Near Bayou Chico, an
area of heavy pumping in close proximity to salt water, about 12 wells
have been abandoned due to salt-water encroachment. This encroach-
ment has been reduced by decreasing pumping near the salt water.
The large Chemstrand plant on the Escambia River just north of
Pensacola uses both river water and ground water from the sand-and-






FLORIDA GEOLOGICAL SURVEY


gravel aquifer. During periods of low flow and high tides, salt water
extends up the river past the plant. At these times, heavy pumping can
cause salt water to enter the aquifer. This happened in Chemstrand well
035-714-4 where the chloride rose to 1,100 ppm before they abandoned
the well. Due to the loss of this well, pumping was decreased in several
other wells to prevent a recurrence of salt-water encroachment. The water
from the other wells, even though low in mineral content, is predominant
in sodium and chloride ions. In central Escambia County the water from
St. Regis Paper Company wells is low in mineral content and has no
predominant chemical constituent.
Water from the sand-and-gravel aquifer in central Santa Rosa County
has a low mineral content and shows no predominant ions. This section
appears to be the major recharge area for the county. This is indicated
by both the low mineral content of the water and the favorable topo-
graphy.
The water in the northwestern section of Santa Rosa County is mainly
of the carbonate type. The limestone of the Floridan aquifer is closest
to the surface in this area. The water in the 445-foot well (051-652-1)
at the Florida State Forest Nursery near Munson shows the effect of
solution of the fossil shells in the lower part of the sand-and-gravel
aquifer. The water had a total hardness of 116 ppm. This type water, al-
though considered moderately hard and undesirable for some domestic
and industrial use, is excellent for agriculture.
A flowing 535-foot well (058-715-1) at Century is high in carbonate.
This is probably due to contact with a limestone bed just above the
aquifer. The constituents in water from this well are carbonate (89
ppm), sodium (62 ppm), and silica (12 ppm). The water contained
practically no calcium, magnesium, or chloride. The presence of sodium
bicarbonate is probably an example of natural softening. The water dis-
solves the calcium carbonate from the limestone; then by ionic ex-
change the calcium is replaced by sodium from clay lenses, which are
numerous in the sand-and-gravel aquifer. The pH of this water is 8.4. An
earlier analysis of a 305-foot well (058-715-2) in this area shows a water
of a similar type.
In the area just west of and parallel to the Escambia River, from
McDavid to Molino, the sand-and-gravel aquifer is apparently divided
into two or more separate aquifers. Wells in the upper aquifer are non-
artesian and range in depth from about 30 feet in the north to 80 feet
in the south. The lower aquifer produces flowing wells which range in
depth from 125 feet in the north to 282 feet in the south. These flowing
wells result from the pressure of water confined beneath a continuous








REPORT OF INVESTIGATIONS No. 40


confining bed or possibly from numerous lenses of confining material. The
flowing wells are for the most part old, and accurate drilling records and
drill cuttings are not available to define definitely the geologic feature.
However, the gradient defined by the well depth tends to follow south-
ward dip of the formations. Figure 42 shows that mineralization of the


) s SAN T A
4.
C) 30
20 ROSA
^71I


D NK
MNo


1.8e0 I
IAO-
1.20- -
I B OI ll.


080-

060- 60
0.40- =/40
0.20- 20
000- -0
2 3 4 5
WELL NUMBER o04-71B.T o04.i -I 0o4-e20-I 0o0-719-I1 o51-7t-I
Figure 42. Graphs showing chemical composition of water from
sand-and-gravel aquifer from Molino to McDavid.


L CI,F, NO3

s o04


Mg CO%, HCO3



102, in ppm



















wells in the


water increases to the south, indicating longer contact between the water
and the minerals in the ground. This limited evidence suggests the pos-
sible existence of a single confining layer extending over several miles.
The increased mineralization in this area is no real problem because
even the most mineralized water in the aquifer is within the limits of
most municipal and industrial criteria. The only exception is that the
silica content of water from all flowing wells' samples exceeds the maxi-
mum allowable limits for boiler feed water.
Generally, the sand-and-gravel aquifer is a source of water of excep-
tionally low mineral content.


M~~






FLORIDA GEOLOGICAL SURVEY


FLORIDAN AQUIFER
In Escambia and Santa Rosa counties the Floridan aquifer is not
used extensively as a source of water. The sand-and-gravel aquifer is
shallower and supplies sufficient water of better chemical quality.
The Floridan aquifer is used as a source of Water in two locations in
eastern Santa Rosa County, one location near the coast and one near the
Alabama State line. The westernmost water well, No. 028-715-2, (1,561
feet deep) in the upper limestone of the Floridan aquifer was drilled
north of Pensacola in 1957. This well was abandoned when the drill
stem test showed a chloride content of 1,495 ppm. A 950-foot well, No.
022-652-1, drilled at Navarre Beach in 1961, produced water of good
chemical quality. Eglin Air Force Base uses several Floridan aquifer
wells on Santa Rosa Island and many in other parts of Okaloosa County
for water supplies.
In northern Santa Rosa County the well (059-658-1) at Camp Hender-
son Lookout Tower in the Blackwater River State Forest produces water
of good chemical quality from the lower limestone of the Floridan
aquifer.
The Floridan aquifer dips to the southwest and is generally too deep
for practical use. The water downdip in the aquifer tends to become
high in chloride, making it unsuitable for most uses.


USE OF WATER
SURFACE WATER
Only a small part of the surface water of the area is being used. Rec-
reation, shipping, cooling, and waste disposal are the major uses at
present (1962). These uses are nonconsumptive in that no water is
permanently removed from the water body. Water used for cooling is
removed from a stream and returned with only a slight rise in tempera-
ture. There are no known major consumptive uses within the area, and
the full potential of the surface waters is far from being realized.
Most uses of surface water are within the southern half of the area.
Principal among these are recreation and shipping. The 230 square miles
of bays are excellent for boating, fishing, swimming, and other recrea-
tional activities. The Intracoastal Waterway parallels the coast and
allows shipping in protected waters to and from Pensacola harbor. The
Chemstrand nylon plant and the Gulf Power plant use water from the
lower Escambia River for cooling. During the three-year period, 1959-61,
the Chemstrand nylon plant used river water for cooling at the rate of







REPORT OF INVESTIGATIONS No. 40


32.4 mgd. Elevenmile Creek is used for disposal of industrial wastes.
Small storage reservoirs are located on Bayou Marcus Creek to enhance
the value of land.
The surface water within the northern half of the two counties is
virtually unused. Several small dams on the Conecuh River in Alabama
regulate slightly the flow of Escambia River. The Florida Game and
Fresh Water Fish Commission operates a fish hatchery in the Blackwater
River Basin near the Santa Rosa-Okaloosa County line. Some of the many
small ponds in the area are used to water livestock.

GROUND WATER
Information was collected from the various users of ground water
within the area in order to estimate the total amount being withdrawn.
These data are essential to show areas of probable overdevelopment
and areas of potential development. Information on the use of ground
water can be compared with water-level graphs to estimate safe with-
drawals from an area.
SAND-AND-GRAVEL AQUIFER
Almost all the ground water used in Escambia and Santa Rosa coun-
ties comes from the sand-and-gravel aquifer. The estimated daily use of
ground water in both counties is about 87 million gallons-approximately
60,000 gpm. Figure 43 shows the approximate amount of ground water
used daily in the two counties for industrial and public supplies. The
quantities of water are represented by the height of the bars. The illus-
tration shows that most of the water is used in southern Escambia
County and southwestern Santa Rosa County.
Use by industries.-Industries use the largest amount of ground wa-
ter in Escambia and Santa Rosa counties. The industries use ground water
at the rate of about 50 mgd. The estimated daily pumpage by industries
is as follows:
Paper and wood products--------------- 34.5 mgd
Chemical plants ..-------... ------------- ------ 13.9 mgd
Other uses (brewing, laundries, etc.) --------1.6 mgd
The St. Regis Paper Company at Cantonment is the largest user of
ground water in the area. The average daily pumpage is 31 mgd (not
fully metered) from 25 wells. The wells were drilled in 1940, 1941, 1944,
1946, 1947, 1951, and 1957 and range in depth from 158 to 485 feet.
Each well has from one to five well screens. Seven wells have been aban-






FLORIDA GEOLOGICAL SURVEY


doned. One deep well (404 feet) was abandoned because of a high
hydrogen sulfide content and six shallower wells were abandoned be-
cause of declining water levels, partially as a result of close spacing.
The Chemstrand Corporation pumped an average of 7.9 mgd (fully
metered) during 1962. This fgure was reduced from a high of 9.2 mgd
during 1959. The plant started production in the fall of 1953. Records
show an average use during the month of 3.4 in June 1954. This use in-
creased to 9.8 mgd in March 1960. Water conservation measures such as


Figure 43. Map of Escambia and Santa Rosa counties showing the amount of ground
water used daily for industrial and public supplies during 1958 and 1962.






REPORT OF INVESTIGATIONS No. 40


the use of cooling towers, reclaiming steam condensate, and repairing
leaks reduced this pumpage even though nylon production increased.
The average pumpage in January 1962 was 6.3 mgd.
Six wells are used almost full time and three wells are on a standby
basis. The three standby wells are pumped at about 500 gpm because
higher rates cause an increase in the chloride content. One well has
been abandoned because of salt-water encroachment. The wells at the
Chemstrand plant range in depth from 312 to 384 feet and are usually
equipped with two well screens.
The Escambia Chemical Corporation near Pace pumps an average of
2.9 mgd from four wells. The wells are from 260 to 300 feet deep and
were drilled in 1955, 1956, and 1962. The Columbia National Corpora-
tion is also near Pace and just west of the Escambia Chemical Corpora-
tion. Columbia National has one well, 293 feet deep, which is pumped
at approximately 1 mgd.
The American Cyanamid Company has two large-capacity wells,
each capable of pumping more than 1,100 gpm. They also have a smaller
well with a pumping rate of 150 gpm. The three wells were drilled in
1957 and are 278 to 288 feet deep. The present plant use is 1.9 mgd and
the water pumped from the two large wells is metered.
The Newport Industries plant at Pensacola has been in operation
since 1916. Thirteen wells have been drilled between 1915 and 1954.
Seven of these wells have been abandoned due to salt-water encroach-
ment. The chloride content of water from four of the other wells has
shown a gradual increase. The increase in the salt content is very slow
and the water from a well may still be used for several years after the
salt content starts to increase. The chloride content of the water from
two of the wells has not increased. These two wells are farther away
from Pensacola Bay than the other wells.
Newport Industries is presently using five large-capacity wells which
are pumped intermittently. They also use one small-capacity well. The
wells range in depth from 209 to 251 feet. The current use of ground
water is 3.6 mgd. Several cooling towers have reduced the ground-water
pumpage.
Use by municipalities.-The second largest use of ground water in
both counties is for public supply. Seventeen million gallons are used
daily for this purpose. About 16 mgd is withdrawn in the greater Pensa-
cola area.
The City of Pensacola sold ground water at an average rate of 11.4
mgd during 1962 for 75,000 people. This is about 150 gallons of water per
person per day. The water is furnished from ten wells that can be







FLORIDA GEOLOGICAL SURVEY


pumped at 2,000 gpm each and three wells of less capacity. The wells
are from 234 to 270 feet deep and are equipped with 100 feet of screen.
The City of Pensacola abandoned six wells near the water plant be-
cause of interference between the closely spaced wells and maintenance
problems caused by the age of the wells. They also abandoned a well
at 12th Avenue and Hayes Street due to obvious industrial waste pol-
lution. The city wells have not experienced salt-water encroachment.
Present plans call for new wells to be located about one mile apart and
one mile from any surface body of salt water.
The People's Water Service in Warrington furnished 2.5 mgd from six
wells in 1962. This company has not had any trouble from salt-water en-
croachment. One well was abandoned in 1960 due to a high iron con-
tent of the water.
The other public water supplies in the Pensacola area were estimated
to pump about 2.2 mgd of ground water in 1962. Public water supplies
are also located in Bagdad, Cantonment, Century, East Milton, Gulf
Breeze, Jay, Milton, and Navarre Beach. The total groundwater pumpage
from these supplies outside and the Pensacola area was estimated to be 1
mgd in 1962. Pensacola Beach obtains its fresh water supply through a
pipe line from the City of Pensacola.
Figure 44 illustrates the increased use of ground water by the City of
Pensacola. In 1933, the average yearly pumpage was 2.09 mgd; the low-
est average monthly pumpage, 1.78 mgd, occurred in March and the
highest average monthly pumpage, 2.42 mgd, occurred in September. In
1962. the average yearly pumpage was 11.4 mgd; the lowest average
monthly pumpage, 8.25 mgd, occurred in February, and the highest
average monthly pumpage, 18.6 mgd, occurred in May. The highest
pumpage in one day was 22.9 mgd on May 23, 1962. Data from the
graph in figure 44 indicate the increased pumping rates that will be
needed in the future.
The cities of Pensacola and Gulf Breeze, and some other local sup-
pliers benefit because of the lower mineral content of the ground water.
The raw ground water requires little treatment and the water can be
treated at the well site. Therefore, the wells can be drilled in the areas
of need and the treated water distributed from the well sites. Many pub-
lic water plants in the other areas must pump the raw water to a central
point where it is treated and then distributed. Treating the water at the
well sites enables the cities to use smaller diameter distribution lines.
This also spaces the wells farther apart. The wider spacing is good prac-
tice because it reduces the large cone of depression caused by pumping
closely spaced wells.







REPORT OF INVESTIGATIONS No. 40


Figure 44. Graph showing pumpage from the sadnd-and-gravel aquifer by the City of
Pensacola, 1933-62.

Use by military opio.-Mil operationsMilitary operations use about 7 million
gallons of ground water per day in Escambia and Santa Rosa counties.
The Naval Air Station at Pensacola uses 5 mgd from 8 wells (200 to 250
feet deep) at Corry Field. The Station has 4 other wells on a standby
basis. Whiting Field uses 1 mgd from 8 wells (234 to 319 feet deep).
Saufley Field, Ellyson Field, Bronson Field, and Eglin Field 7 use a total
of 1 mgd.
Use by agriculture.-The amount of ground water used for irrigation
in both counties is small. About 0.5 mgd is used for irrigation. Lawn and
garden irrigation accounts for most of the water used. Less than 10 large-
capacity wells are occasionally used in this area for irrigation. Eseambia
County has about 300 acres under occasional irrigation. The need for ir-
rigation water normally is not great because rainfall is fairly abundant
during the growing season. However, seasonal droughts occur and a few






FLORIDA GEOLOGICAL SURVEY


farms have produced excellent truck crops by using ground water for
sprinkler irrigation.,
The amount of ground water available far exceeds the quantity
needed for irrigation, especially in the northern half of the counties. In
some places, part of the water used for irrigation percolates downward
to recharge the sand-and-gravel aquifer near where it was pumped.
Santa Rosa and Escambia counties have about 30,000 cattle, horses,
and mules. Assuming a use of 12 gallons of water per animal per day, the
daily use of water would be 360,000 gpd. The swine population of both
counties is about 20.000. A use of 4 gallons of water per animal per day
gives 80,000 gpd. The estimated daily use of water for the 110,000
poultry flock is 15,000 gpd. The daily use of water in Escambia and
Santa Rosa counties for livestock is about 0.5 mgd.
Supplies for domestic use.-A sufficient quantity of ground water for
domestic use can he obtained by wells almost any place in Escambia
and Santa Rosa counties. Wells in the area are usually less than 150 feet
deep, and many of them are less than 100 feet deep. The wells are
screened in the permeable sand or gravel. The permeable zones, in
which the screens are set, are located by inspection of the drill cuttings
while the well is being drilled.
The estimated number of persons using ground water from private
wells for domestic purposes is 60,000 in Escambia County and 20,000 in
Santa Rosa County. Assuming an average use of 150 gallons of water
per person per day for domestic purposes, they would use water at a rate
of 9 mgd in Escambia County and 3 mgd in Santa Rosa County. The
amount used is only a small part of the total amount available. As each
well withdraws only a small amount of water, and because the wells are
widely spaced, the effect of this pumping on the water table is slight.

FLORIDAN AQUIFER
The quantity of water withdrawn from the Floridan aquifer by
wells in Escambia and Santa Rosa counties is very small. Only about 8
wells obtain water from this aquifer in both counties. The use of water
from this aquifer is small because sufficient quantities can be obtained,
generally, from the overlying sand-and-gravel aquifer, because the wa-
ter is usually higher in mineral content than water from the sand-and-
gravel aquifer, and because deep wells are expensive.
The upper limestone of the Floridan aquifer in the southeastern cor-
ner of Santa Rosa County is important. This aquifer provides the only
major source of fresh ground water at Navarre Beach on Santa Rosa Is-
land. Well 022-652-1 was drilled in 1961 to a depth of 950 feet and had






REPORT OF INVESTIGATIONS No. 40


a natural flow of 110 gpm. The artesian pressure head was 51 feet above
the land surface and about 56 feet above sea level. The chloride content
of the water is 87 ppm and the dissolved solids is 380 ppm. Water from
this well is soft as the hardness is only 16 ppm.

WATER PROBLEMS
Problems concerning water resources can be divided into those re-
sulting from natural causes, those arising from man's use of water, and
those resulting from a combination of both.

PROBLEMS FROM NATURAL CAUSES
Water problems arising from natural causes are usually associated
with too little or too much rainfall, the areal geology, or by the mineral
content of the water. Deficient rainfall causes the water level in wells
to decline, runoff from streams to decrease, and pond levels to be low-
ered. Excessive rainfall may cause flooding of lands that are poorly
drained and lands adjacent to streams. Problems of water development
occur in areas where the geology is such that aquifers are limited. The
mineral content of water may limit the usefulness of the water.

PERIODS OF LOW RAINFALL
Decline of water levels.-The relation of ground-water levels to rain-
fall is shown by the hydrographs of wells in this area. During periods of
low rainfall, the water level declines. This may result in drying up of
shallow wells and salt-water encroachment. In well 031-716-1 at Ensley,
the water level dropped more than 9% feet in 1950 and again in 1954
(fig. 34). These declines were due to a reduction in recharge brought
about by below-normal rainfall.
The levels of ponds drop during low rainfall periods and some ponds
go dry. Streamflow decreases during the dry periods.
Salt-water encroachment.-Low ground-water levels and below-normal
streamflow, brought about by lack of rain, allow salt-water encroachment
into surface and ground-water supplies. During periods of low rainfall
the streamflow decreases and the salt-water front moves upstream.
Lowered ground-water levels may allow upward or lateral salt-water
encroachment. Upward encroachment is possible where the lower aqui-
fer has a higher head than that in the upper aquifer. Lateral encroach-
ment into ground water from surface bodies of salt water is possible
where ground-water has a lower level than the surface water level. The






FLORIDA GEOLOGICAL SURVEY


greatest danger of salt-water encroachment occurs during periods of low
rainfall in areas of heavy pumping.
Lateral salt-water encroachment occurred along the north and south
shoreline of Gulf Breeze peninsula in 1954. This encroachment was a
result of low ground-water levels caused by the low rainfall. The salt
water moved inland 30 to 40 feet from Pensacola Bay and 20 to 30 feet
from Santa Rosa Sound.
PERIODS OF HIGH RAINFALL
Periods of moderately high rainfall are important because the amount
of ground water in storage is increased and streamflow becomes greater.
However, severe problems such as floods or ponded water may result
from excessive rainfall.
Every stream in the area responds to rain falling in its basin, The
height to which a stream will rise depends on the amount and distribu-
tion of rain and the physical characteristics of the river basin, The stages
of some of the smaller streams in the area vary as much as 15 feet while
stages of some of the larger streams vary as much as 36 feet. The
magnitude and frequency of floods are important to engineers in charge
of designing river appurtenances (bridges, dams) and other structures
in the flood plain. Data on the magnitude and frequency of floods in the
area are presented in figure 20.
Ponded water occurs in areas where the land is flat and drainage fa-
cilities are inadequate. Examples of this are found near Pensacola. Water
stands in low spots for varying lengths of time after each intense rain.
This pounded water leaves some areas only by evaporation and infiltra-
tion. In these areas the problem can be made worse by developments
such as paved streets, houses, and lawns, that cause an increase in the
rate of runoff to the pounded areas. The problem of ponded water can
be solved by providing adequate drainage.
Ponded water can also occur where the water table intersects the
land surface. This happened near the city of Gulf Breeze during the fall
of 1959 when intense rains caused the water table to rise rapidly (fig.
3S) and low lands were flooded. The figure shows the slow decline of the
water table following the abrupt rises. Surface drainage, buried tile
drains, or pumping are the most effective methods for removing the
excess water.

MAN-MADE PROBLEMS
Water resource problems caused by man are usually associated with
heavy withdrawal of ground water in an area; the pollution of ground







REPORT OF INVESTIGATIONS No. 40


water or surface water by industrial wastes; or structures that alter
drainage, infiltration, or runoff characteristics.
LARGE DRAWDOWNS
Industries usually require a continuous supply of water. Pumping of
ground water causes drawdowns of the water level in proportion to the
number and spacing of wells and the rate of pumping. Such drawdowns
increase the cost of pumping water, but more important, may cause the
cone of depression to extend outward farther than is desirable and may
cause local depletion and reduced well yield.
An example of large drawdowns can be found at Cantonment. Figure
34 shows that the water level in well 036-719-1 declined more than 42
feet from 1941 to 1956. This decline was mainly the result of heavy
pumping although low rainfall was a contributing factor. During the 15-
year period, the water level declined at an average rate of 2.8 feet per
year. The reasons for the rise of the water level from 1957 to 1962 are
covered on page 68.
SALT-WATER ENCROACHMENT
Salt-water encroachment can be a serious "side effect" when water
levels near bodies of salt water are lowered. If the sediments between
the salt-water body and the ground-water aquifer are relatively imperme-
able, the rate of salt-water encroachment is slow; if these sediments are
relatively permeable, the rate of encroachment is much higher.
An example of a slow rate of encroachment is shown by industrial
wells near Bayou Chico where several years of heavy pumping lowered
water levels below sea level (fig. 37). As a result of this lowering, water
from wells nearest the bayou slowly became salty, and it became neces-
sary to drill replacement wells farther away from the bayou. Usually
several years were required after the chloride content of the water from
a well started to increase before the water became too salty for use.
Pumping of ground water at Newport Industries averaged 2.5 mgd
from 1928 to 1933, The average ground-water level at Bayou Chico-
prior to pumping was about 7 feet above sea level. Jacob and Cooper
(1940, p. 60-64) calculated that the minimum time required for salt wa-
ter from Bayou Chico to move 2,000 feet to the Newport Industries well
field would be about 3.1 years, on the assumption that there was close
interconnection of the aquifer and bayou and that permeability was
constant, They further determined that salt-water encroachment from
Bayou Chico would not begin until the ground-water level had been
lowered 7 feet and that it would take a pumping rate of more than 3.4







FLORIDA GEOLOGICAL SURVEY


mgd. which was reached in 1928. After 1928, the chloride content of the
water pumped at Newport should have increased about 3 years later,
or by 1931. The rise in salinity did not become apparent until 1937. The
salt water probably took about 6 years to pass through the 20-foot thick
bed of clay.
An example of rapid encroachment occurred along the Escambia
River at the Chemstrand nylon plant. The salt-water encroachment into
the sand-and gravel aquifer at the Chemstrand plant comes from the
Escambia River by lateral movement. This conclusion was reached after
considering all the known factors. Prior to pumping at the Chemstrand
plant, ground water moved eastward toward the Escambia River and
seeped into the river. Ground-water pumping lowered the ground-water
level and eventually caused water from the Escambia River to infiltrate
into the ground. The water that infiltrates is salty part of the time.
The river infiltration explains why the ground-water levels at Chemstrand
have generally stabilized.
The other possible source of salt-water encroachment at the Chem-
strand plant is from salt water below the sand-and-gravel aquifer. A
study of resistivity logs of wells indicates that the water in a thick clay
section (fig. 6) below the sand-and-gravel aquifer at Chemstrand is salty.
As the clay is virtually impermeable, the salt water is not believed to
come from this source. This thick clay bed prevents salt water from
moving up from the limestones below it. In addition, the chloride con-
tent of water from the upper limestone of the Floridan aquifer is only
400 ppm which is not salty enough to cause the high chloride content
sometimes found in well 035-714-4.
The Bucatunna Clay Member is more than 200 feet thick at the
Chemstrand plant. The effectiveness of this clay bed as a confining
layer can be inferred by a comparison of the chloride content of water
from the adjoining limestone beds. The chloride content of water from
the upper limestone (above the Bucatunna) is 400 ppm and the chloride
content of water from the lower limestone (below the Bucatunna) is
7,3() ppm.
Well 035-714-4 (Chemstrand Well No. 3) is the production well near-
est the Escambia River. The water from this well was the first to show an
increase in the chloride content. If the salt-water encroachment was from
below, the center wells of a well field are usually the first ones to show
an increase in the salt content of the water. In 1955, nearby pumping
caused the ground-water level near the river to decline below sea level
for the first time and it has remained below sea level most of the time
since June 1955. In 1956, the chloride content of water from well 085-







REPORT OF INVESTIGATIONS No. 40


714-4, 500 feet west of the Escambia River, increased from about 6 to
more than 1,100 ppm.
During 1957 and 1958, the chloride content of the Escambia River at
the Chemstrand nylon plant cooling water intake was above 25 ppm for
about 25 percent of the time. Thus, the salt-water front had advanced
at least 7 miles above the mouth of the river.
The flow of the Escambia River during the summer of 1955 was
sufficient to keep the salt-water front downstream from the Chemstrand
nylon plant. In September 1955, the flow of the Escambia River de-
creased and salt water probably occurred at the plant. As the ground-
water level was below river level, salt-water encroachment began. The
time required for the river water to move to Chemstrand well (035-
714-4) 500 feet from the river was calculated. Assume an average draw-
down of 20 feet (which would also be about 20 feet below sea level); an
aquifer thickness, m, of 300 feet; and a porosity, p, of 30 percent. The
coefficient of transmissibility, T, is 150,000 gpd per foot. The hydraulic
gradient, g, would be 20 feet in 500 feet or 0.04. These values and the
following calculation would give the minimum time required for river
water to move to the well. No allowance is made for the time required
for the water to move through the clay beds in the sand-and-gravel
aquifer.
V- Tg
7.48 mp
(150,000) (0.04)
V (150,000) (0.04) 8.9 feet per day
S(7.48) (300) (0.30)
500 feet
= 56 days
8.9 feet per day -
The time required for the salty water from the river to move to the
well field would be about two months and the salt water in the well
could have been expected sometime in November 1955. The salt water did
not show up in the well until almost one year later. This lag can be ex-
plained by the time required for the water to pass through several thin
clay beds.
Figure 45 shows the lowering of ground-water levels and their rela-
tion to the level of the Escambia River. The figure is a cross section from
Cantonment eastward to the Escambia River. Early data imply that the
ground-water level close to the river was 25 to 30 feet above sea level
in 1940. The water table was 12 to 15 feet above sea level near the river
in 1951 and about 1.5 mgd per mile was moving toward the Escambia



































Dec----- S-E L
DMEAN SEA LEVEL


--- MEN SEA LEVEL


Figure 45. Cross section showing the decline of water levels in the vicinity of Cantonment.


Highest river level
+8.19' obove msl







REPORT OF INVESTIGATIONS No. 40


River from the west. Since 1955, the water table adjacent to the river has
usually been below river level at the Chemstrand plant and water from
the river has infiltrated into the well field. Ordinarily infiltration from the
river would be a desirable feature as it would recharge the aquifer and
decrease the drawdowns. However, the Escambia River is salty part of
the time and infiltration introduces salt water into the sand-and-gravel
aquifer adjacent to the river.
INDUSTRIAL WASTE DISPOSAL
The complex problem of disposing of industrial wastes is very im-
portant because these wastes can pollute both surface and ground-water
supplies. A thorough knowledge of the geology and hydrology of an area
is invaluable in planning for safe disposal of industrial waste. Some in-
dustries in this area presently discharge wastes directly into streams,
bays and infiltration ponds.
Disposing of waste into surface-water bodies may cause objectionable
odors, kill fish and plant life, discolor the water, and cause the accum-
ulation of solid waste materials. A knowledge of streamflow is very help-
ful in determining the dilution necessary to keep the concentration of
plant wastes below an objectionable level.
Discharging industrial wastes into infiltration ponds may result in
pollution of the sand-and-gravel aquifer because in most cases the water
level in infiltration ponds stand above the ground-water level, especially
when the ground-water level is lowered by heavy pumping. Thus, the
pond has the head potential to recharge the aquifer. The permeability
of the coarser sediments and presence or absence of clay layers help
determine how fast water from infiltration ponds will move downward
and then laterally.
The disposal of industrial wastes into infiltration ponds occurs in the
northern part of Pensacola. Concentrated acid wastes have been dis-
charged into a pond for more than 70 years. This waste material has in-
filtrated into the ground and moved with the hydraulic gradient. A di-
luted form of this waste has been detected in the water from a Pensacola
municipal well at 12th Avenue and Hayes Street, more than a mile from
the pool. This well subsequently was abandoned. The average velocity
of ground water was previously computed to be about 100 feet per year
in the Pensacola area. Therefore, the acid wastes could move 6,000
feet in about 70 years (an average of about 86 feet per year).
A knowledge of the geology and hydrology in an area may prove use-
ful to solve some problems of waste disposal. Information collected dur-
ing this study enabled officials of the Chemstrand Corporation to in-






FLORIDA GEOLOGICAL SURVEY


vestigate the possibility of disposing of some plant wastes underground.
A thick section of limestone, the lower limestone of the Floridan aquifer,
lies from 1,370 to 1,955 feet below the plant (see fig. 7). This limestone
lies between two clay beds which restrict the movement of water from or
into the limestone aquifer. The clay beds continue outward under the
Gulf of Mexico. Water in the lower limestone moves with the hydraulic
gradient to the south or south-southeast from the plant. The diluted
wastes would probably be discharged into the Gulf of Mexico many miles
from Pensacola and many years later.
A study of electric logs indicates all the water in the lower limestone
is very salty, except possibly a small amount near the top of the aquifer.
On March 20, 1963, the chloride content of the water from the lower
limestone of the Floridan aquifer at the Chemstrand plant was 7,300
ppm. This salty water was coming from well 035-714-5 which was open
to the aquifer at a depth of 1,390 to 1,729 feet.
Test drilling will be necessary to determine the character, the poros-
ity and permeability of the limestone; and the artesian pressure head
and salinity of the water. Monitor wells should be drilled to determine
the movement of wastes and the hydraulic gradient.
This underground disposal of wastes could be used by other indus-
tries in the southern third of the area. Care must be taken to insure that
fresh-water supplies above the limestone would not be contaminated
by leaking or corroded well casings.


POTENTIAL WATER SUPPLIES
SURFACE WATER
Escambia and Santa Rosa counties have an abundance of fresh water
-8.5 bgd flow from the area through surface streams. However, the
surface-water supplies vary with respect to time and location. The fluc-
tuation with respect to time follows the pattern of rainfall. The drainage
areas and average flows of streams in Escambia and Santa Rosa counties
are given in table 1. About 2.0 bgd is derived from the land area within
the two counties.
The average flow from the Perdido River basin is 1.1 bgd. This flow
is equivalent to 1.2 mgd per square mile over the entire basin. Not all
tributary streams flow at the same rate as the average for the basin. The
major tributaries of the Perdido River in Escambia County and their
computed flows are: Brushy Creek, 90 mgd; McDavid Creek, 40 mgd;
Jacks Branch, 16 mgd; and Bayou Marcus Creek, 60 mgd.








REPORT OF INVESTIGATIONS No. 40


The Escambia River has an average flow of 4.5 bgd. Pine
Creek is a tributary stream in northern Escambia County and
average flow of 184 mgd. Canoe Creek in northeast Escambia
has an estimated flow of 50 mgd, and Moore Creek in Santa Rosa
has a computed flow of 40 mgd.


Barren
has an
County
County


Table 1. Drainage areas and average flows of streams in Escambia and Santa Rosa
counties, Florida

Drainage Area Average Flow
(square miles) (million gallons per day)
1ItvKn BASIN
In Escambia From Escnambia
Total and Santa Rosa From basin and Santa Rosa
counties counties

Perdido Iiver ............... 02 230 *1,120 **284
Brushy Creek ....... ...... 75 53 00 05
McDavid Creek ............ 34 34 40 40
.lucks Branch... .......... 24 24 1i> 10
BVayou Malrcus Creek ....... 20 20 *00 **00
Carpenter Creek .. ... ... 18 18 *20 **20
Escamubia River........... 4.,233 410 *4,540 **556
Pine Barren Creek ........... 8 85 134 116
Moore Crek ................ 32 32 40 40
Canoe Creek................ 37 24 50 30
Blackwater River............ 800 580 *900 **710
Pond Creek................. 88 88 80 80
Big Coldwater Creek......... 241 228 350 330
Big Juniper Creek........... 140 134 170 155
Ytllow River .............. 1,305 115 *1,620 **130
Coastal Drainage............ 300 300 *220 **220

Total Flow into Bays....... ................................ 8,540
** Total Flow from Counties... ..... ............ .................. .... 1,908

The average flow from the Blackwater River basin is 960 mgd. About
three-fourths, or 710 mgd, is derived from Santa Rosa County. Most of
the remaining 250 mgd is from Okaloosa County, with a small amount
coming from Alabama. Pond Creek has an average flow of 80 mgd. Big
Coldwater Creek has the largest flow (350 mgd) of any tributary in the
Blackwater River basin. Big Juniper Creek has an average flow of about
170 mgd.
An average flow of about 1,620 mgd enters Blackwater Bay from the
Yellow River. Most of this flow comes from counties to the east.







FLORIDA GEOLOGICAL SURVEY


GROUND WATER
SAND-AND-GRAVEL AQUIFER
Although nearly all the ground water being used in Escambia and
Santa Rosa counties comes from the sand-and-gravel aquifer, the full
potential of the aquifer is not utilized. Figure 5 illustrates the general
area of potential development of ground-water in Escambia and Santa
Rosa counties. An understanding of the limiting factors is necessary if
the sand-and-gravel aquifer is to be fully utilized. The limiting factors
were considered to help designate the general areas shown in figure 5.
Areas of abundant fresh ground water.-Large ground-water supplies
in the sand-and-gravel aquifer can be developed in the northern half of
Escambia and Santa Rosa counties. Only a minor amount of the available
ground water in these areas is being used at the present time. The thick-
ness of the sand-and-gravel deposits ranges from about 230 to almost
1,000 feet. Generally, these deposits are more than 400 feet thick. Figure
5 shows other areas where large supplies can be developed, such as
northwest of Pensacola and north of Navarre. Small or domestic supplies
of water can be developed most anywhere in the two counties except
close to the shores of the narrow islands.

Factors which limit the amount of fresh ground water.-
1. Concentrated pumpage: Heavy, continued pumping can cause
a cone of depression to extend a considerable distance outward from a
well field, perhaps far enough to overlap a cone created by another well
field. Both well fields then, in effect, compete for the water and the
resultant drawdown of the water level is correspondingly greater. The
areas where large supplies have been developed are shown in figure
5. Additional development in these areas should be carefully planned.
2. Proximity to salt water: The Gulf of Mexico, Santa Rosa Sound,
and all the bays contain salty water. In addition, wedges of salt water
extend for varying distances up the streams that empty into the bays.
Where the water table has been depressed by pumping, salt water from
these sources may invade fresh-water supplies. Figure 5 shows the areas
of potential danger from salt-water encroachment.
3. Presence of clay lenses: The sand-and-gravel aquifer contains
lenses of clay and sandy clay which decrease the permeability of the
aquifer. The total amount of clay is highly variable. As these clay lenses
are relatively impermeable they limit the quantity of water that can be
withdrawn from the aquifer at any given place.







REPORT OF INVESTIGATIONS No. 40


However, in certain areas these clay beds retard the encroachment
of salt water. For example, the clay bed 60 to 80 feet below the surface
in the vicinity of Gulf Breeze retards the vertical movement of the un-
derlying water when heavy pumping lowers water levels in the overly-
ing sands. The water just below the clay bed is salty near the shorelines
of the Gulf Breeze Peninsula.
Another example of clay beds that prevent salt-water encroachment
is at Fort Pickens on the western tip of Santa Rosa Island. Here, the clay
and sandy clay beds are almost 300 feet thick. Below the clay beds is a
sand aquifer where fresh water for the Fort is obtained. The clay keeps
the salt water out even though the water level in this sand has been be-
low sea level since at least 1913. The chloride content of the water from
the wells at Fort Pickens is about 80 ppm and has not increased ap-
preciably since 1940. The fresh water in the sand is believed to come
from the mainland southwest of Pensacola and to move southward
under Pensacola Bay.
4. Industrial wastes: Wastes from industrial plants can contaminate
ground-water supplies when the wastes are discharged into ponds or on
the ground. Wastes discharged into streams or rivers also can contami-
nate ground-water supplies where pumping lowers the ground-water
level below stream or river level.
5. Residual salt water: Salt water that is not completely flushed
from the sand-and-gravel aquifer is another limiting factor. This salt
water probably entered the aquifer in the past when sea level stood
higher than at present. Such salt water was found at a depth of 75 feet at
Fair Point on Gulf Breeze Peninsula.

FLORIDAN AQUIFER
The Floridan aquifer is almost untapped by water wells in Escambia
and Santa Rosa counties. A detailed appraisal of the possibility of devel-
oping large supplies of potable water from this aquifer was not possible
in 1962. Studies of well cuttings and electric logs from oil-test holes and
deep water wells have established the location and thickness of the
aquifer. Little is known of the ability of the upper limestone of the Flo-
ridan aquifer to transmit water except in the southern part of Santa Rosa
County. The water transmitting and water storing properties need to be
determined by test drilling and aquifer tests. The chemical quality of
the water needs to be determined from water samples collected during
the test drilling.
Wells drilled into the upper limestone of the Floridan aquifer in
southern Santa Rosa County have large yields. The water is under artesian







100 FLORIDA GEOLOGICAL SURVEY

pressure and wells 5 to 6 inches in diameter drilled at lower elevations
yield from 50 to several hundred gallons per minute by natural flow.
A study of electric logs indicates that the water in the upper lime-
stone of the Floridan aquifer is fresh except in the southwestern part of
Santa Rosa County and the southern half of Escambia County. The logs
also indicate that the water in the lower limestone of the Floridan aqui-
fer is fresh in the northern part of both counties and salty in the southern
part.
Any proposed user of water from the upper limestone of the Floridan
aquifer in southeastern Santa Rosa County might expect a gradual de-
cline of the artesian pressure head. The decline of the artesian pressure
head is presently centered around Fort Walton Beach. At Holley and
Navarre, the artesian pressure head declined about 20 feet from 1942 to
1961. The same rate of decline of about one foot per year is expected
to continue in the Holley-Navarre area. This decline means that in the
future some wells will stop flowing and the yield by natural flow from
other wells will decrease somewhat.








REPORT OF INVESTIGATIONS No. 40


REFERENCES

Barraclough, J. T.
1962 (and Marsh, O. T.) Aquifers and quality of ground water along
the Gulf Coast of Western Florida: Florida Geol. Survey Rept.
Inv. 29.
Black, A. P.


1951 (and Brown, Eugene) Chemical character of Florida's waters-
1951: Florida State Board Cons., Div. Water Survey and Research
Paper 6.
1953 (and Brown, E., and Pearce, J. M.) Salt water intrusion in Florida:
Florida State Board Cons., Div. Water Survey and Research Paper 9.
Brown, Eugene (see Black, A. P., 1951, 1953).
Calver, J. L.
1949 Florida kaolins and clays: Florida Geol. Surv. Inf. Circ. 2.
Carlston, Charles W.
1950 Pleistocene history of coastal Alabama: Geol. Soc. America Bull.,
v. 61, no. 10, p. 1119-1130.
Clark, W. E. (see Heath, R. C.)
Collins, W. D.
1923 The industrial utility of public water supplies in the United States:
U.S. Geol. Survey Water-Supply Paper 496.
1928 (and Howard, C. S.) Chemical character of waters of Florida: U.S.
Geol. Survey Water-Supply Paper 596-G.
Cooke, C. Wythe
1945 Geology of Florida: Florida Geol. Survey Bull. 29.
Cooper, H. H., Jr., (see Jacob, C. E.)
Ferguson, G. E.
1947 (and Lingham, C. W.; Love, S. K.; and Vernon, R. O.) Springs of
.Florida: Florida Geol. Survey Bull. 31.
Gunter, Herman (see Sellards, S.)
Heath, R. C.
1951 (and Clark. W. E.) Potential yield of ground water on the Fair


Howard, C. S.
Howe, Henry'
1936

Jacob, C. E.


Point Peninsula, Santa Rosa County, Florida: Florida Geol. Survey
Rept. Inv. 7.
(see Collins, W. D.)
V.
Stratigraphic evidence of Gulf Coast geosyncline: Proceedings of
the Geol. Soc. of America for 1935, p. 82 (abstract).


1940 (and Cooper, H. H., Jr., and Stubbs, S. A.) Report on the ground-
water resources of the Pensacola area in Escambia County, Florida:
U.S. Geol. Survey open-file report.
Lingham, C. W. (see Ferguson, G. E.)
Lohr, E. W.
1954 (and Love, S. K.) The industrial utility of public water supplies in
the United States, 1952; Pt. I-States east of the Mississippi River:
U.S. Geol. Survey Water Supply Paper 1299.
Love, S. K. (see Ferguson, G. E.; Lohr, E. W.)


101







FLORIDA GEOLOGICAL SURVEY


MacNeil, F. S
1949

Marsh. O. T.
1962


Matson, C. C
1913

Musgrove, R.
1961


Patterson, A.
1955

Pearce, J. M.
Pride. R. W.
1958

Sanford, S. (s
Sellards, E. I


>.
Pleistocene shore lines in Florida and Georgia: U.S. Geol. Survey
Prof. Paper 221-F.

Relation of the Bucatunna Clay Member (Byram Formation Oligo-
cene) to geology and ground water of westernmost Florida: Geol.
Soc. of America Bull. v. 73, p. 243-252.

(and Sanford, S.) Geology and ground water of Florida: U. S. Geol.
Survey Water-Supply Paper 319.
H.
(and Barraclough, J. T.; Marsh, O. T.) Interim Report on the Water
Resources of Escambia and Santa Rosa counties, Florida: Florida
Geol. Survey Inf. Circ. 30.
0.
Surface water in Florida: Florida Engineering and Industrial Ex-
periment Station Bull. 72, p. 32-34.
(see Black, A. P.)

Floods in Florida, magnitude and frequency: U.S. Geol. Survey
open-file report.
ee Matson, G. C.)
I.


1912 (and Cunter, Herman) The water supply of west-central and west
Florida: Florida Geol. Survey 4th Ann. Rept.
Stubhs, S. A. (see Jacob, C. E.)
Vernon, R. O. (see Ferguson, G. E.)


102




Water resources of Escambia and Santa Rosa Counties, Florida ( FGS: Report of investigations 40 )
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Permanent Link: http://ufdc.ufl.edu/UF00001227/00001
 Material Information
Title: Water resources of Escambia and Santa Rosa Counties, Florida ( FGS: Report of investigations 40 )
Series Title: ( FGS: Report of investigations 40 )
Physical Description: x, 102 p. : ilus., maps (1 fold. col.) ; 23 cm.
Language: English
Creator: Musgrove, Rufus H
Barraclough, Jack T ( joint author )
Geological Survey (U.S.)
Publisher: s.n.
Place of Publication: Tallahassee
Publication Date: 1965
 Subjects
Subjects / Keywords: Groundwater -- Florida -- Escambia County   ( lcsh )
Water-supply -- Florida -- Escambia County   ( lcsh )
Groundwater -- Florida -- Santa Rosa County   ( lcsh )
Genre: non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by Rufus H. Musgrove, Jak T. Barraclough, and Rodney G. Grantham.
General Note: "Prepared by the United States Geological survey in cooperation with the Florida Geological Survey, Escambia County, Santa Rosa County, and the city of Pensacola."
General Note: "References": p. 101-102.
 Record Information
Source Institution: University of Florida
Rights Management:
The author dedicated the work to the public domain by waiving all of his or her rights to the work worldwide under copyright law and all related or neighboring legal rights he or she had in the work, to the extent allowable by law.
Resource Identifier: aleph - 000958542
oclc - 01750266
notis - AES1352
lccn - a 65007677
System ID: UF00001227:00001

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i*








STATE OF FLORIDA
STATE BOARD OF CONSERVATION

DIVISION OF GEOLOGY


FLORIDA GEOLOGICAL SURVEY
Robert O. Vernon, Director




REPORT OF INVESTIGATIONS NO. 40





WATER RESOURCES

OF

ESCAMBIA AND SANTA ROSA

COUNTIES, FLORIDA


By
Rufus H. Musgrove, Jack T. Barraclough, and
Rodney G. Grantham


Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
FLORIDA GEOLOGICAL SURVEY,
ESCAMBIA COUNTY, SANTA ROSA COUNTY,
and the
CITY OF PENSACOLA


Tallahassee
1965







vl 4o
AGRI-
CULTURAL
LIBRARY
FLORIDA STATE BOARD

OF

CONSERVATION


HAYDON BURNS
Governor


TOM ADAMS
Secretary of State




BROWARD WILLIAMS
Treasurer




THOMAS D. BAILEY
Superintendent of Public Instruction


EARL FAIRCLOTH
Attorney General




RAY E. GREEN
Comptroller




DOYLE CONNER
Commissioner of Agriculture


W. RANDOLPH HODGES
Director






LETTER OF TRANSMITTAL


{r^ tJt ^7eoiyoacai s irveyf

TALLAHASSEE

January 28, 1965

Governor Haydon Burns, Chairman
State Board of Conservation
Tallahassee, Florida

Dear Governor Burns:

The Florida Geological Survey is publishing the "Water Resources of
Escambia and Santa Rosa Counties, Florida," as its Report of Investiga-
tions No. 40. This report was prepared from a cooperative program be-
tween the U. S. Geological Survey, the Florida Geological Survey,
Escambia County, Santa Rosa County, and the City of Pensacola.
As you know, Escambia and Santa Rosa counties are the westernmost
counties in Florida. Much of the recent industrial growth of this section
of Florida has been placed in this area. The impact and demand for
water resources have been greatly accelerated, and this study was un-
dertaken by this department, the counties, and the City of Pensacola,
through the cooperative program to monitor the salt-water-fresh-water
contact, to determine the total demand for water at the moment, and to
try to meet the future needs of the area. I believe that the details pre-
sented in the report will meet the intended purpose.

Respectfully yours,
Robert O. Vernon
Director and State Geologist



























Completed manuscript received
November 30, 1964
Published for the Florida Geological Survey
By Rose Printing Company
Tallahassee
1965







PREFACE


This report is the result of a 4-year investigation dealing with the
water resources of Escambia and Santa Rosa counties, Florida. The mild
climate and excellent water supplies are prime reasons for industrial de-
velopment in this section of Florida. Information on the water resources
of the area prior to this investigation was sketchy and based on a
minimum of documented data. The purpose of this project was to collect
water data to combine with data previously collected into an interpreta-
tive report that will be beneficial to water users.
In 1958, the U.S. Geological Survey in cooperation with the Florida
Geological Survey began a detailed investigation of the surface-water
and ground-water resources of Escambia and Santa Rosa counties, Flor-
ida. The investigation was financed by the U.S. Geological Survey, the
Florida Geological Survey, Escambia and Santa Rosa counties, and the
city of Pensacola.
The investigation was made by the following personnel of the Water
Resources Division of the U.S. Geological Survey: Rufus H. Musgrove,
hydraulic engineer, Surface Water Branch; Jack T. Barraclough, hydrau-
lic engineer, Ground Water Branch; and Rodney G. Grantham, chemist,
Quality of Water Branch. Owen T. Marsh, geologist, Ground Water
Branch, did the basic geologic study and was transferred before the
completion of the investigation. The work was supervised by A. O.
Patterson, district engineer, Surface Water Branch; M. I. Rorabaugh,
succeeded by C. S. Conover, district engineers, Ground Water Branch;
and J. W. Guerin, district chemist, succeeded by K. A. Mac Kichan,
district engineer, Quality of Water Branch.
Appreciation is expressed to the many individuals who furnished in-
formation and in particular to the following persons for providing infor-
mation and extending courtesies which greatly facilitated the investiga-
tion:

M. E. Batz, B. T. Dean, C. P. Neiswender, and C. A. Witcher, Jr.-
The Chemstrand Corporation
D. W. Young, C. E. Adams, and J. A. Hamm, Jr.-St. Regis Paper
Company
E. L. Russell, W. E. Moore, H. E. Province, Duncan Goldthwaite,
J. F. Schindler, and J. S. Porter-The California Company
R. C. Howard and M. F. Kirby-Gulf Oil Corporation
Stanley Sweeney and J. P. Bowers-Water Department, city of
Pensacola





PREFACE


J. J. Pinke-American Cyanamid Company
J. J. Petruska-Newport Industries Division
A. G. Symons-Layne-Central Company
C. G. Mauriello and Robert Schneider-Bureau of Sanitary Engineer-
ing, Florida State Board of Health
Lehmon Spillers-Spillers Well and Pump Company
D. M. Harvey-Harvey Hardware and Mill Supply








CONTENTS

Page
Abstract .. .... ... -- ....... -- ..........-.. ----............----- --- 1
Introduction _--- --- --- -----_---. --------------- 2
Purpose and scope --..---.-.--- --.----.. ----.---......-- -- 2
Previous work ---- ---- ------- ---- 3
Description of the area -...--.--.--.....------.--.... --- ----.---. 4
Rainfall -_..............-....--_...-_ _.... .......----- ----.. 6
Temperature ..------...--..- ...---............-_.---..-----. -- 8
Well-numbering system ...----............---.......---------...--- 8
Geology ............-. ..-_ ---......- ............ ..... 9
General statement _--- --------------- 9
Collection of data .--......----- ---......- --- --....... -.--- 9
Stratigraphy _......... ........------------.--- 11
Aquifers --------------.----------- --------------- --- --- 11
Sand-and-gravel aquifer ---......--.-- --------------- -------------. --- 11
Floridan aquifer _..-- -.... -_ -.. .....--- --.- ----.- 16
Aquicludes ----_- ......... ~____--..- .----- 18
Aquicludes within the sand-and-gravel aquifer ----- ---- 18
Aquicludes below the sand-and-gravel aquifer -- 20
Aquicludes within the Floridan aquifer __ -_----- 21
Aquiclude below the Floridan aquifer --------- -------- 21
Regional dip __- __ -__------ 21
Relation of geology to ground water -----..----.. ------. ---------- ---- 23
Movement of water -..............----.-- .------..----- ---- ----- 23
Relation of geology to quality of water ------23
Zones of fresh and salty water ---------------- 23
Mineralization and hardness of ground water ------- 24
Relation of quality of water to geologic history of the Gulf Coast -- 24
Surface water ..--..-----...... --------------...................----- 25
Collection of data ___-- 27
Flow-duration curves ------ -_29
Perdido River basin ------_______----- 30
Occurrence of water ------... ------.--- ---- --- 30
Mineral content ...-----... --. ..........----- -- ----.....- 39
Escambia River basin -. ..--------. ...--..-.....--- -.- 39
Occurrence of water --------------__--- --- ---- 39
Mineral content ....------.__ ...--.--- --..---.---------- 47
Blackwater River basin ...------...---- ----..---...----..--- 49
Occurrence of water .....---------------.--------- ----------. -- 49
Mineral content --------- --- ----------- 55
Yellow River basin _-----------------------55
Occurrence of water ---- -- ------------ 55
Mineral content --- ------- -------.----------- 55
Ground water -------- _-- --- -- --- -------- 56
Principles of occurrence ___ ----_--- 56
Hydrologic properties of the aquifers -- -56
Sand-and-gravel aquifer -----------57






CONTENTS


Page
Floridan aquifer --_-57
Movement of water ________-58
Ground-water velocities ______ -62
Areas of artesian flow _________63
Fluctuation of the water level _____ _______64
Temperature of ground water ______-__--72
Specific capacity _-_ --- --------------___ -- 73
Quantitative studies _-___ 73
'Mineral content ____76
Sand-and-gravel aquifer ------- 76
Floridan aquifer ___ 82
Use of water 82
Surface water ____________82
Ground water _________ 83
Sand-and-gravel aquifer __ 83
Use by industries ______ 83
Use by municipalities 85
Use by military operations __87
Use by agriculture ____87
Supplies for domestic use ____ _---___88
Floridan aquifer __88
Water problems ___89
Problems from natural causes _____ ________--------89
Periods of low rainfall ______ _89
Decline of water levels _____----__ --__-__ ------89
Salt-water encroachment ___...___ 89
Periods of high rainfall ____---------___---__-90
Man-made problems ------_____ 90
Large drawdowns ------------__-- 91
Salt-water encroachment ________91
Industrial waste disposal --- -------- -- 95
Potential water supplies ____96
Surface water _____----------____-- 96
Ground water _____-________--- --98
Sand-and-gravel aquifer ---------- 98
Areas of abundant fresh ground water ____ --_ 98
Factors which limit the amount of fresh ground water -____ 98
Floridan aquifer 99
References ___----________---____-- 101









ILLUSTRATIONS

Figure Page
1. Map of Florida showing location of Escambia and Santa Rosa counties 5
2. Graph of rainfall at Pensacola, Fla., and Brewton, Ala., showing monthly
averages, maximums and minimums, and yearly rainfall for the period
1926-61 ___ 7
3. Map of Florida showing the well-numbering system 8
4. Geologic sequence in Escambia and Santa Rosa counties, as shown by
representative log of oil test well near Pensacola 10
5. Map of Escambia and Santa Rosa counties showing locations of selected
wells from which information was obtained and the water supplies that
can be developed from wells in the sand-and-gravel aquifer __ 10
6. Geologic section across Escambia and Santa Rosa counties showing aqui-
fers and aquicludes along section A-A' in figure 11 _12
7. Geologic section along the Gulf Coast from Mobile Bay to the Choctaw-
hatchee River showing aquifers and aquicludes 14
8. Geologic section showing faces changes and zones of relative permeabil-
ity and impermeability in the upper part of the sand-and-gravel aquifer
along the Perdido River, Escambia County ____ ______ 15
9. Map of Escambia and Santa Rosa counties showing contours on top of
the lower limestone of the Floridan aquifer 18
10. Map of Escambia and Santa Rosa counties showing contours on top of the
Miocene clay units -_ --- 20
11. Map of Escambia and Santa Rosa counties showing contours on top of the
Bucatunna Clay Member of Byram Formation __ 22
12. Approximate average annual runoff, in inches, from areas within Escam-
bia and Santa Rosa counties __----- 26
13. Runoff in inches for 1961, a year of high runoff, and for 1956, a year of
low runoff, from areas within Escambia and Santa Rosa counties --- 27
14. Basin map of Perdido, Escambia, Blackwater, and Yellow rivers _--- 28
15. Graph showing periods and types of surface-water records in and near
Escambia and Santa Rosa counties ___ __- 29
16. Map of Escambia and Santa Rosa counties showing surface drainage and
data-collection points _-- ---------- 30
17. Flow-duration curves for 5 streams in Escambia County 31
18. Flow-duration curves for 5 streams in Santa Rosa County -- 32
19. Channel-bottom profile for lower Perdido River ------- ---- 33
20. Regional flood frequency curves for the Perdido, Escambia, Blackwater,
and Yellow rivers _- ---- 35
21. Low-flow frequency curves for Perdido River at Barrineau Park,
1941-61 __ 36
22. Graph of the minimum, average, and maximum monthly discharge of
the Perdido River at Barrineau Park, 1941-61 37
23. Channel-bottom profile for lower Escambia River 41
24. Channel-bottom profile of Pine Barren Creek ----- --42
25. Discharge available without storage, Pine Barren Creek near Barth,
1952-61 _____ 43
26. Mass-flow curve for Pine Barren Creek near Barth, 1952-58 44






ILLUSTRATIONS AND TABLES


Figure Page
27. Graph of the minimum, average, and maximum monthly discharge of the
Escambia River near Century, 1935-61 __ 46
28. Relation of daily chloride content in water in Escambia River at Chem-
strand plant to streamflow at State Highway 4 near Century, October-
December 1959 and October-December 1960 __ 48
29. Channel-bottom profile of Pond Creek 50
30- Low-flow frequency curves for Big Coldwater Creek near Milton,
1938-61 52
31. Graph of minimum, average, and maximum monthly discharge of Big
Coldwater Creek near Milton, 1938-61 53
32. Channel-bottom profile of lower Blackwater River 54
33. Water levels in an artesian well and two nonartesian wells drilled into
the sand-and-gravel aquifer in northern Escambia County and graph of
monthly rainfall at Pensacola __ 60
34. Cross section showing geology and hydrology in northern Escambia
County 61
35. Hydrograph of wells 037-645-1 and 032-648-1 ___ 65
36. Hydrographs of wells 031-716-1, 036-719-1, and 036-716-1 and graph of
yearly rainfall at Pensacola _____67
37. Hydrographs of wells 024-715-1, 024-715-2, and 023-716-2 ..--- 69
:38. Hydrograph of well 021-709-8 and graph of the rainfall at Pensacola 71
39. Graph showing theoretical drawdowns in the vicinity of a well 76
40. Map of Escambia and Stanta Rosa counties showing mineral content of
water from the sand-and-gravel aquifer -- 77
41. Map showing types of water from wells in the sand-and-gravel aquifer 78
42. Graphs showing chemical composition of water from wells in the sand-
and-gravel aquifer from Molino to McDavid ------- 81
-3. Map of Escambia and Santa Rosa counties showing the amount of ground
water used daily for industrial and public supplies during 1958 and
1962 ____ 84
44. Graph showing pumpage from the sand-an-gravel aquifer by the City of
Pensacola, 1933-62 87
45. Cross section showing the decline of water levels in the vicinity of
Cantonment ______--- 94



TABLES
Table Page
1. Drainage areas and average flows of streams in Escambia and Santa
Rosa counties, Florida ------ 97









WATER RESOURCES
OF
ESCAMBIA AND SANTA ROSA
COUNTIES, FLORIDA

By
Rufus H. Musgrove, Jack T. Barraclough,
and Rodney G. Grantham


ABSTRACT
Escambia and Santa Rosa counties, the westernmost counties in
Florida, have an abundant supply of both ground and surface water of
excellent quality. A 4-year study was made to determine the quantity
and quality of the water and the possible effect of municipal and indus-
trial expansion on the water.
Over 8.5 bgd (billion gallons per day) of fresh water flow into the
200 square miles of estuarine bays from four major rivers. Only about 5
per cent of this water is used. The Escambia River, the fifth largest in the
state, has an average flow of over 4.5 bgd. Many smaller streams within
the area produce large quantities of water.
Most of the 87 mgd (million gallons per day) of water taken from
the ground comes from the sand-and-gravel aquifer. This aquifer extends
from the water table down to various depths ranging from 200 to 1,000
feet. In parts of this aquifer the water is confined under artesian pressure
by numerous layers of clay and hardpan. The sand-and-gravel aquifer
contains a large supply of exceptionally soft and unmineralized water.
The Floridan aquifer, consisting of limestones which underlie the
sand-and-gravel aquifer, contains a large supply of harder, more mineral-
ized artesian water, and is virtually untapped.
Recharge of the sand-and-gravel aquifer is by local rainfall. The
Floridan aquifer is recharged by rain falling in southern Alabama, 10 to
35 miles north of the area, and by downward leakage from the sand-and-
gravel aquifer.
Factors such as decline of the water table, salt-water encroachment,
and contamination of surface and ground water can greatly affect the
availability of water of good quality. Decline in the water table may be
caused by below-normal rainfall or heavy pumping of closely spaced
wells. Salt-water encroachment is likely to occur where heavy pumping






FLORIDA GEOLOGICAL SURVEY


of wells near salty bays or estuaries lowers the water table below sea
level. Contamination can be brought about by disposing of wastes
directly into rivers and bays, or by seepage from waste basins to the
water table.
Industries use about 60 percent of the ground water withdrawn from
the area: St. Regis Paper Company, the largest user in the area, pumps
31 mgd. Chemstrand, using 31.5 mgd, is the largest user of surface
water in the area. The large amount of surface and ground water being
used by industries and municipalities is only a small part of the usable
supply of the area.

INTRODUCTION

PURPOSE AND SCOPE
An immediate need of community and industrial planners in Escam-
bia and Santa Rosa counties is information on the water resources of the
area. It is presently known that the area has a large supply of surface
and ground water that is low in mineral content. However, because the
water needs of this fast growing section of Florida are becoming greater,
information about other characteristics of the water must be made avail-
able so that the area may realize its full industrial potential without
creating problems caused by permanently lowered water levels, salt-
water encroachment, and pollution.
An investigation of the water resources of Escambia and Santa Rosa
counties was started in January 1958 by the U.S. Geological Survey in
cooperation with the Florida Geological Survey, Escambia and Santa
Rosa counties, and the city of Pensacola. This investigation was designed
to obtain, over a 4-year period, data on the occurrence, quality, and
quantity of surface and ground water. The information collected during
the investigation will serve two major purposes: (1) it will provide an
inventory of the water of the area; and (2) it will provide a sound basis
for planning development and use of the water resources of the area.
The purpose of this report is to make available information on the
quantity and quality of water in the area collected prior to 1962. It
contains a brief discussion of climate, a geologic description of the area,
information on streamflow and streamflow characteristics, principles of
the occurrence and movement of ground water, properties of the
ground-water aquifers, and chemical characteristics of the water re-
sources of the area. It discusses present use of water, some existing
problems associated with water, and potential water supplies of the area.






REPORT OF INVESTIGATIONS No. 40


PREVIOUS WORK
The earliest published report that describes the water resources of
Escambia and Santa Rosa counties was by Sellards and Gunter (1912);
it discusses the water supply of west-central and west Florida. This
report describes the physiography, drainage, water wells, and soils of
Escambia and Santa Rosa counties. It contains information, on wells in
Santa Rosa County at Bagdad, Blackman, Cobb, Milligan, Milton, Mulat,
Pace, and Robinson Point. Data are supplied for wells in Escambia
County at Cantonment, Bohemia, Molino, Muscogee, Pine Barren, Mc-
David and Pensacola, including chemical analyses of water from several
of these wells. The report also contains a map (p. 95) showing areas
of artesian flow in the two counties.
The following year (1913) Matson and Sanford published a report
on the geology and ground water of the entire State. They briefly de-
scribe the physiography, geology, and water supply of Escambia and
Santa Rosa counties (p. 301-304; 401-403). Data on typical wells and
general information on water resources of selected towns are tabulated
for each of the two counties.
Streamflow records have been collected on the Escambia River since
1934, on Big Coldwater Creek since 1938, and on the Perdido River
since 1941. Daily records of flow for these rivers are published by the
U.S. Geological Survey in the annual series of water-supply papers.
The first detailed investigation of ground water in the area was made
by Jacob and Cooper (1940). The report contained a section on geology
by Sidney A. Stubbs. The study included pumping tests of both the
drawdown type and the recovery type to obtain coefficients of trans-
missibility and storage for the aquifer in the vicinity of Pensacola. Since
1940, continuous and periodic measurements have been made of the
water levels in wells as far north as Cantonment to determine the effect
of rainfall, pumping, barometric pressure, and tides. Jacob and Cooper
also had chemical analyses made of water from several wells and
studied the encroachment of salt water from Bayou Chico into wells of
the Newport Industries and of the U.S. Navy.
The mineral spring at Chumuckla in Santa Rosa County is briefly
described by Ferguson, Lingham, Love, and Vernon (1947) in their
report on the springs of Florida.
Heath and Clark (1951) made a detailed investigation of the poten-
tial yield of ground water in the vicinity of Gulf Breeze on Fair Point
Peninsula, Santa Rosa County. Twenty test wells were drilled across the
peninsula, and periodic water-level measurements were made to obtain






FLORIDA GEOLOGICAL SURVEY


profiles of the water table. Heath and Clark conducted quantitative
studies to determine the effect of pumping in relation to salt-water
encroachment and to determine how much ground water could be
pumped from wells. They give a brief but adequate discussion on the
geology and cover such topics as use and quality of ground water.
Chemical analyses of ground water in the two counties have been
published by the U.S. Geological Survey (Collins and Howard, 1928)
and by the Florida State Board of Conservation (Black and Brown,
1951). Black, Brown, and Pearce (1953) give a short description of the
intrusion of salt water into wells of the Newport Industries and of the
U.S. Navy near Pensacola. Chemical analysis of water from Pensacola
city wells was published in a report by Collins (1923, p. 33). Another
analysis of water from these wells was published by the U.S. Geological
Survey (Lohr and Love, 1954, p. 111).
Stubbs (in Jacob and Cooper, 1940, p. 5-12) describes the upper 300
feet of geologic deposits in the southern half of Escambia County. Heath
and Clark (1951, p. 12-15) describe the same interval on Gulf Breeze
Peninsula. Cooke (1945, p. 232-233) describes a short measured section
exposed in the bluffs on the west side of Escambia Bay. He also noted
the presence of several Pleistocene marine terraces in Escambia and
Santa Rosa counties. MacNeil (1949) and Carlston (1950) likewise rec-
ognize the existence of several marine terraces in the area. Calver's
report on Florida kaolins and clays (1949, p. 24-28, 41-42) gives infor-
mation on clays in Escambia and Santa Rosa counties and indicates which
clays he believes have commercial value. The first detailed geologic study
of Escambia and Santa Rosa counties was made by Marsh (1962) in
connection with the comprehensive investigation of the water resources
of the area. An interim report of that investigation (Musgrove, Barra-
clough, and Marsh, 1961) summarizes the geology and water resources
of the two counties. Barraclough and Marsh (1962) describe the geology
and water resources of the southern half of Escambia, Santa Rosa,
Okaloosa, and Walton counties.


DESCRIPTION OF THE AREA

Escambia and Santa Rosa counties are in the extreme northwest
corner of Florida (fig. 1). Escambia County is the westernmost county
in the State and is bordered by Alabama on the west. Both counties
border on Alabama to the north and on the Gulf of Mexico to the south.
Water courses serve as boundary lines on three sides of Escambia County






REPORT OF INVESTIGATIONS NO. 40


and two sides of Santa Rosa County. The Perdido River is the boundary
line between Florida and Alabama on the west and the Escambia River
separates the two counties. Santa Rosa is the larger, but less populous
county, with 1,151 square miles and a 1960 population density of 25.6
persons per square mile. Escambia County covers 759 square miles and
had a 1960 population density of 229 persons per square mile.


Figure 1. Map of Florida showing location of Escambia and Santa Rosa counties.

The two major cities in the area are Pensacola and Milton. Pensacola,
located in southern Escambia County on Pensacola Bay, had a population
of 56,752 in 1960. Greater Pensacola includes several small suburban
communities and thus has a much greater population than Pensacola
proper. Milton is the largest town in Santa Rosa County, with a popula-
tion of 4,108 in 1960.
Much of the land in the southern part of the area is less than 30
feet above sea level. Bays, low marshy areas, peninsulas, and islands with
long shorelines characterize this section. Estuarine bays extend inland
some 20 miles and cover over 200 square miles. Santa Rosa Island is
about half a mile wide and 55 miles long and extends from the mouth






FLORIDA GEOLOGICAL SURVEY


of the Pensacola Bay eastward. Sand dunes on the island are as high as
55 feet above sea level. North of Pensacola the land is hilly and well
dissected with streams that drain toward the Pensacola area. The eleva-
tions of the streambeds are sea level for distances of 30 to 40 miles inland
from the coast. The hills 20 miles inland are about 150 feet above sea
level, becoming higher to the north. The highest land elevations, 290 feet,
are along the northern boundary of the counties.
Agriculture is the principal industry of the northern half of the area.
Much of the area is devoted to forest. The Blackwater River State
Forest occupies the northeastern quarter of the Santa Rosa County. Row-
crop farming is prevalent throughout the northern half of the area. In-
dustrial operations predominate in the section south of Cantonment and
Milton. Chemicals, synthetic fibers, and paper are the major products of
the local industries. Raw materials from many parts of the State are
shipped to the industrial area around Pensacola for processing and
manufacturing. Military operations, tourists, shipping, and fishing also
contribute to the economy of the area.

RAINFALL
To evaluate the effect of rainfall on the water resources of the area, a
study was made of records collected by the U.S. Weather Bureau at
two stations for a 36-year period, 1926-61. Data for these two stations
are presented in graphical form in figure 2. The rainfall data at Pensacola
were selected to represent the rainfall in the southern part of the area
along the coast. Data from the Brewton station, located in Alabama about
10 miles north of the State line, were selected to represent the rainfall
farther inland.
Within the two-county area there seems to be only minor long-term
variations in amounts of rainfall. The difference between the Pensacola
and Brewton averages for the 36-year period is only 0.46 inch. The shorter
the period of time for which rainfall is measured at any two points, the
greater the difference may be. A 1-year period can show uneven distri-
butions. For example, in 1953 Pensacola received one-third more rain-
fall than Brewton. The pattern was reversed in 1929 when Brewton had
87.18 inches and Pensacola had a below-average rainfall of 60.79 inches.
The average rainfall, based on the 36 years of record at the Brewton and
Pensacola stations, is about 63 inches per year. The year-to-year variation
can be great at any one point. For example, the highest and lowest an-
nual rainfall occurred in successive years at Pensacola-90.41 inches in
1953 and 28.66 inches in 1954.







REPORT OF INVESTIGATIONS No. 40


PENSACOLA, FLA.
-- i 1001---------- -----------
soo

= BO -------- ------1 I ---- ~ ----il-
S36-
i -,.
__- .* ,* ,- F. S- _~ ~_-- *- -- -
W -- -
I *'* iT i i *




NIII 0 o- o
II ,^ -HIIIIIllIt


a a 6


BREWTON, ALA.
25 100

to MAXIMoUM so I

2 z





0 0

Figure 2. Graph of rainfall at Pensacola, Fla., and Brewton, Ala., showing monthly
averages, maximums and minimums, and yearly rainfall for the period 1926-61.


The pattern of seasonal distribution is the same over the entire area,
the wettest periods occurring in early spring and late summer and the
driest in October and November. Except during October and November,
an average rainfall of at least 4 inches each month can be expected.
October and November have an average rainfall of about 2.9 inches and
3.8 inches, respectively. An average rainfall of over 6.0 inches occurs dur-
ing March, July, August, and September. July has the highest average,
with 7.4 inches. There is always the possibility, however, of having a dry
month during normally wet seasons or a wet month during seasons
which are usually dry. For example rainfall in October has varied from
near zero to a maximum of 20.5 inches at Pensacola, and March,
normally a wet month, has experienced as little as 0.9 inch of rainfall.
Another interesting aspect of the rainfall of the area is the high
intensity-as much as 0.6 inch has been measured during a 5-minute
period. Rainfalls of 3.5 inches during a 1-hour period and daily rainfalls
in excess of 6.0 inches are not uncommon.


N VO






8 FLORIDA GEOLOGICAL SURVEY

TEMPERATURE

Temperatures in the area are mild. The average annual temperature
at Pensacola is 68'F. Average monthly temperatures vary from a high of
810F in July and August to a low of 54F in December and January. The
extreme temperatures recorded at Pensacola have been as high as 103F
and as low as 7F; however, they seldom rise above 100F or drop
below 200F. On the average, 275 frost-free days occur annually. Winter
temperatures may be as much as 10F higher along the coast than in
the northern part of the area.


WELL-NUMBERING SYSTEM

The well-numbering system that is derived from latitude and longi-
tude coordinates is based on a state-wide grid of 1-minute parallels

C ees 'A 1-9hde -eT of the Gree-nr Engl-nd. pr-me m-4d-an

'"G EOR A
^^*^ r-;--^ l'_r< ...--. :.l --"



Figue /. .ap o d s' t w m i



45 V-
:9-.c __ ....... .-............. ..-- ..i .oo' "' .... O







1: :+ +
S::::::::::::. .::::::::L -:1: 31: + .' '. ', ......-

~ ?---~. -rt i -- -.





.. ... 3__ .. ....

.. 2r o. s .es .




Figure 3. Map of Florida showing the well-numbering system.






REPORT OF INVESTIGATIONS No. 40


of latitude and 1-minute meridians of longitude. The wells in a 1-minute
quadrangle are numbered consecutively in the order inventoried. In
Florida, the latitude and longitude prefix north and west and the first
digit of the degree are not included in the well number.
The well number is a composite of three numbers separated by
hyphens: the first number is composed of the last digit of the degree
and the two digits of the minutes that define the latitude on. the south
side of a 1-minute quadrangle; the second number is composed of the
last digit of the degree and the two digits of the minutes that define
the longitude on the east side of a 1-minute quadrangle; and the third
number gives the numerical order in which the well was inventoried in
the 1-minute quadrangle (fig. 3).

GEOLOGY
GENERAL STATEMENT
In Escambia and Santa Rosa counties, a thick sequence of sand,
gravel, and clay extends from the surface to as much as 1,000 feet
(fig. 4). Nearly all the wells in this area tap permeable sediments within
this sequence-referred to as the sand-and-gravel aquifer (Musgrove,
Barraclough, and Marsh, 1961). In the northern half of the area, the
sand-and-gravel aquifer lies on the upper limestone of the Floridan
aquifer, but in the southern part, the two aquifers are separated by a
thick clay unit of Miocene age which serves to confine the water that
is present in the upper limestone of the Floridan aquifer. An extensive
clay bed, the Bucatunna Clay Member of the Byram Formation, under-
lies the upper limestone of the Floridan aquifer and forms an aquiclude
throughout the area (Marsh, 1962).'the lower limestone of the Floridan
aquifer underlies the Bucatunna and rests upon relatively impermeable
clay and shale. Within the area, no fresh-water aquifers occur below the
lower limestone of the Floridan aquifer. A more detailed report of the
geology of the Florida Panhandle was prepared by Marsh.

COLLECTION OF DATA
Information has been collected on about 600 water wells in this
area. Figure 5 shows the location of the wells in Escambia and Santa
Rosa counties. They range in depth from about 15 feet to over 1,800
feet but most of them are between 30 and 300 feet deep. They range in
diameter from 1%i inches to 30 inches. Most of the domestic-supply wells
are 1, to 4 inches in diameter and most of the industrial supply wells are









FLORIDA GEOLOGICAL SURVEY


Sand, !:ght-brcan, very coarse; -
and gravel


Sand, ':ght grey, fine to very coarse;
mollusk shells
G-- I Coy, sandy -
Sand, very coarse; shells; and gravel

Mollusk shells with some fine to very
Coarse sand
LJ
;CC
o Grave! and shel:s and medium
S to very ccarse sand
7 Cv d sell gfrayg -
S Gravel =rd sell fragments


LJ
0 U
-00

0


,:cy, gray, sandy


Limestone, gray:sh white, and dark
gray clay

Limestone, light gray, fossils rare

ana, medium to very corse, and
tfne crave
Limestone, grayish white, some
crominifers in lower half



Clay, dark gray; a little pyrite and
carbonaceous material


Limestone, white, coundant
foraminifers


AOUICLUDE
(Cloy units of Miocene age
absent in northern half of Escambia
and Santa Rosa Counties)


LOWER LIMESTONE
OF THE
FLORIDAN AQUIFER


Figure 4. Geologic sequence in Escambia and Santa Rosa counties as shown
by representative log of oil test well near Pensacola.


o SCO
u acc-

0


zCCC






:2CC -


3 3CC-


-CC-

4CC




.6CC-


'BCC
;acc-


9CC-


2CCC -




I












3100


-i

*L































,2 Well and well number
- "Area where bel 00 gp, or


Areas where wells of 100 to 250
.HII^LL








.
















EXPLANATION
'2 Well and well number
m Areas where wells of 1000 gipm or
mwaeore capacity cn be developedraw
Areas where wells of 250 to 1,000en
gpnm capacity can be developed
Areos where wells of 100 to 250
gpm copocily con be developed.
*N Areas where large quantities of
water ore withdrawn
A r Areas subject to sal-wOater encroach-
ff ment if large-caupacity wells ore
closely spaced and heavily pumped,
Small to moderate supplies of water
can be developed.










GULF BE
7 --- --- I-
U
G


BOGIv


7T


CHUMUCKLA


""-'^L;0 :tm """ ztL""" '"":^ i1 {L""zti/--itzit


DI VKN ~-I ~


,k, 1 k


0 2 3 4 5 6 7 8 9 10 miles

- I l I I I I I I I I I I I I I i i i I I I I I


U Fr L I ~-- ---__ -- -,


87000


Figure 5. Map of Escarubia and Santa Rosa counties showing locations of selected
wells from which information was obtained d nd the watcr supplies that can be
developed from wells in the sand-and-gravel aquifer.


m


H __( 8.0 .4.. -1


3100'


NZ


4


S I I


30a1'


87040


S30010'
6045'


m


Fy~ ~1


I---l--c--t- -I--, ,+--t--~


J I H J I J -- l! 1 1 111 1 1 7 1 1-_


*^^.ym r -nr 1- 1@14 '^-TIP-in I^


r


H ri ( I


W0' 86'45'


+h ,^1


tI N .1.


Its!F~ BY
PE5OA FC


0


II


9 A M I A C 0 N Y A L A AM A- ..


S0o N TY 5 SANT RO UN

I -. ....r ,
?A
y "C NT

-H I Il I I Y -'










REPORT OF INVESTIGATIONS No. 40


10 to 24 inches in diameter. About 99 percent of the wells draw water
from the sand-and-gravel aquifer and the rest draw water from the
Floridan aquifer.
The larger-diameter wells tapping the sand-and-gravel aquifer are
constructed by drilling an open hole until permeable strata (generally
coarse sand or gravel) are encountered. Screens are then set in these
permeable zones. Almost all of these wells are equipped with screens.
The wells obtaining water from the Floridan aquifer are constructed
by drilling an open hole into the limestone, then casing the well to the
top of the limestone. The water is obtained from the uncased limestone
section. Sometimes an open hole is drilled to the top of the limestone,
the casing is firmly seated into the limestone, and drilling is continued
into the limestone below the bottom of the casing.
In 1959 and 1960, the U.S. Geological Survey contracted to have 31
test wells drilled, by the rotary method, in Escambia and Santa Rosa
counties. There were three main purposes for these test wells. First,
they helped to delineate aquifers and aquicludes in parts of the area
where little or no geologic information was available. Geologic logs of
wells were compiled from an examination of rock cuttings that were
collected at intervals of 5 or 10 feet. Fossils were picked from the rock
cuttings and were identified to determine the ages of the geologic for-
mations. Electric logs of the two deepest wells were made to determine
accurately the position of the clay layers and permeable zones. Second,
these test wells were used to establish a grid of water-level observation
wells in areas where information on water levels was needed. Third, 20
of the wells in Santa Rosa County were used to determine the water
budget (water gains and losses) for a small topographic drainage basin.
A total footage of 5,175 feet was drilled, and the depths of the wells
ranged from 32 to 750 feet.


STRATIGRAPHY
AQUIFERS
Sand-and-gravel aquifer.-Virtually all of the wells in Escambia and
Santa Rosa counties draw their water from the sand-and-gravel aquifer.
This aquifer extends from the surface to various depths, ranging from
200 feet in the area 7 miles northwest of Milton to 1,000 feet in the area
14 miles northwest of Milton (fig. 6). In the northern half of the area,
the sand-and-gravel aquifer overlies a thin limestone of late Oligocene
age (the upper limestone of the Floridan aquifer), but in the southern






















I I IL I I f" ,a -I
I/ ? R ~ 1600





4 1

IV oo
1.a400
1,600


CLPA)
EXPLANATION
? I L 4 L I I 1' 9 lO mimi
Length of I clian abooual mnI
Vtricaal lalurall, ooulal 31 Ii as
SeClln iakln dinclly do 'n li rn itnal dill
Canlocti lluld on awll cultlmngl ld elgtllae lII
]I II Tha i 1i polgaeflid fnam
Naimal,, al faorm n mndCate t ni plan s Ailmos alq i smile ..
lilIOna ol mowa mInIl ata Itiea II at u Intoa plant f Uncoaa miiy
section


200


.j 600

W00
1AW
1.0a

Q I.200.


SAND AND -


GRAVEL


Figure 6. Geologic section across Escambia and Santa Rosa counties showing
aquifers and aquicludes along section A-A' in figure 11.






REPORT OF INVESTIGATIONS No. 40


half of the area the sand-and-gravel aquifer rests upon a thick clay unit
of Miocene age (fig. 7). The aquifer ranges in age from Miocene to
Recent.
Abrupt faces changes are characteristic of the sand-and-gravel
aquifer. Although composed predominantly of sand, the aquifer contains
numerous lenses and layers of clay and gravel that are as much as 60
feet thick. The discontinuity of the sediments in the sand-and-gravel
aquifer is shown in figure 8. This is a detailed geologic section of the
uppermost 100 feet of the aquifer along the Perdido River in west-
central Escambia County. The cross section is based on rock cuttings
and electric logs of 20 test wells. These wells were drilled for the St.
Regis Paper Co. to test the infiltration characteristics of the ground
along the Perdido River. The logs were made by the firm of Leggette,
Brashears, and Graham, consulting ground-water geologists. As can be
seen from the cross section, irregular lenses of gravel and clay extend
for short horizontal distances. For example, one gravel lens that is 20
feet thick is only about 200 feet long. Well logs of the sand-and-gravel
aquifer elsewhere indicate that this cross section is fairly representative
of the aquifer throughout the area.
The uppermost 5-20 feet of the sand-and-gravel aquifer differs
markedly from the underlying beds. This upper part consists of light
tan, fine to coarse sand that is soft and loose in contrast to the hard,
reddish brown, pebbly sand that underlies it. In many places, the light
tan sand has been removed by erosion, leaving the hard reddish brown
sand exposed as a flat surface.
The sand-and-gravel aquifer consists predominantly of quartz sand,
ranging from white to light brown or reddish brown. Although some
beds of sand are moderately well sorted, the unit as a whole is generally
rather poorly sorted. The grains range from very fine to very coarse and
are commonly mixed with granules and small pebbles of quartz and
chert. The sand grades laterally into stringers and lenses of gravel which
are made up chiefly of pea-sized pebbles. In addition to the large lenses
of clay within the aquifer, small stringers of white to gray clay are
scattered throughout. Fragments and layers of black lignite are found
occasionally and at many places throughout both counties layers of black
carbonaceous sand and gravel, containing twigs and bits of coal, are
exposed at the surface. These layers range in thickness from a few inches
to more than 2 feet.
It seems likely that the materials in the upper part of the sand-and-
gravel aquifer were deposited in an environment similar to that of the
present-day Mississippi River delta. This is suggested by the rapid faces















BA.r1.". :0 Nrr FiCAMPA C*I Nr AAJT.1 SAY A A P CCOh0,fr I :0U.Ir fA ;, '
,ASll A &a AI I IA i

0- OAP Ili -L 0
SAN 0 ANiD -- GRAVEL AQUIFER Yea 000
2 00- .-- ... .......... 2.00
60020
000 M C~ N~ ~ ...-...........Dc
400F 400
6- 000 150




240
800- Y eOO
1000 C( E AOLFR uIFFRi~lo
S12600
14 00- NQIIAI o200
M30t 0 r 0014
41500iiAN AWUFER
leoo O,,LtOE 5a J OIAS OFN F LOR10N 10
t,2000- jp? L~C 00
t~2OWLVER C~Y2200

2600i~LE: 20
2800.-21BO
3000-i
y I;ie a to s r 3000
WOO-anr


EXPLANATION
LInqI' at I soila 11 miles
V4nPIrhcal gaqq..afn aaut 52 tinns
-UMneformity


Well inclane dl?0 ton4 ci
1.01cna along lstre cd beai


0 0 20 30miles
Map rsnownq COi,,c aof cross uthan R-*R

Figure 7. Geologic section along the Gulf Coast from Mobile Bay to the Choctaw-
hatchee River showing aquifers and aquicludes.


0



;ti


,.,















6-- Portion of sand and grovel 60
aquufer shown by section r[a Cros section based an electric logs and sample logs ao test 4uM
ra- ve. .. wells drilled by the St Regis Paper Company in 1956 t in-
-. 00 .estigate infiltration Charactersties of the ground along
Iwon ,S ;OAN.UIFOGRVEL.I Grvel andnd n the Perddo River Logs were made by Leggette, R dd i.
OCE6aa-an- Sand geologists, New York) and correlated by Owen T Marsh CROSS sCION















*Relatively permem able zone
Sg120ry sO- 1or AY.s- 120
120- 6 m s Sr sand ad iand lay
L, 140 Clay 140 -





o- ....... ..... :. .
W20- ..20






00 1 m0e


140 _' 'm" m .r-140

Figure 8. Geologic section showing faces changes and zones of relative permeability
and impermeability in the upper part of the sand-and-gravel aquifer along the
Perdido River, Escambia County.








FLORIDA GEOLOGICAL SURVEY


changes, the absence of fossils, and the abundance of sand and gravel.
These sediments were probably deposited by a network of streams
whose channels were constantly shifting back and forth across the sur-
face of the delta. In this environment, clay was deposited in quiet pools
or abandoned channels while gravel was being laid down by swiftly
flowing streams nearby.
Parts of the sand-and-gravel aquifer have a rather high average
porosity and permeability and are thus excellent reservoirs for ground
water. The aquifer consists principally of relatively insoluble quartz
grains which accounts for the remarkably low mineral content and soft-
ness of this water. In contrast to the rest of Florida, the ground-water
conditions in Escambia and Santa Rosa counties are complicated by the
great lithologic variability of the aquifer. Ground water is under artesian
pressure where lenses and layers of clay, sandy clay, or hardpan overlie
a saturated, permeable bed. Ground water is under non-artesian con-
ditions where such clays and hardpan are absent or where the perme-
able bed is not completely saturated. It is not uncommon for a well to
tap both artesian and non-artesian water. Ground water in the sand-and-
gravel aquifer is derived almost entirely from rain falling in the area.
Floridan aquifer.-In the northern half of the area, the sand-and-
gravel aquifer is underlain by a thick sequence of limestones known col-
lectively as the Floridan aquifer. In the southern half of the area the
two aquifers are separated by a thick clay unit of Miocene age (fig. 4).
The Floridan aquifer in Escambia and Santa Rosa counties is divided
into two parts by an extensive clay bed (Bucatunna Clay Member of
the Byram Formation) near the top of the aquifer. The part that lies
above this clay bed was named the upper limestone of the Floridan
aquifer and the part below the clay was named the lower limestone of
the Floridan aquifer (Musgrove, Barraclough, and Marsh, 1961).
The upper limestone of the Floridan aquifer is chiefly the Chicka-
sawhay Limestone of late Oligocene age. Within the area, this formation
ranges in thickness from about 30 to 130 feet. Its upper surface is an
erosional unconformity of low relief which dips gently toward the
southwest at about 23 feet per mile. The Chickasawhay is typically a
brown to light-gray hard dolomitic limestone or dolomite with a distinc-
tive spongy-looking texture. It contains abundant shell fragments. Sev-
eral wells in the area obtain water from this limestone.
In the southern part of the area, the Chickasawhay Limestone is
overlain unconformably by a remnant of the Tampa Limestone of early
Miocene age. This is a cream-colored to light-gray, soft to hard, sandy







REPORT OF INVESTIGATIONS No. 40


limestone which contains shell fragments and abundant foraminifers.
The Tampa reaches a maximum thickness of 270 feet in southern Escam-
bia County. The Tampa contains several beds of clay which would re-
duce the effective porosity and permeability of the limestone. A few
wells in the southern part of the area obtain water from this limestone.
The upper limestone is recharged mainly by rain that falls in
Conecuh, Escambia, and Monroe counties, Alabama. This is the area
where the upper limestone comes to the surface. Additional recharge
comes from downward leakage of water from the sand-and-gravel aqui-
fer in northern Escambia and Santa Rosa counties, Florida. The move-
ment of the water in the upper limestone is generally southward and
southeastward.
The lower limestone of the Floridan aquifer in this area consists of
the Ocala Limestone and other limestones of Eocene age. The top of the
lower limestone, although an erosional unconformity, is a relatively flat
surface that dips gently toward the southwest (fig. 9). The lower lime-
stone rests unconformably upon shale and clay of middle Eocene age.
The lower limestone ranges in thickness from about 360 feet in central
Escambia County to as much as 1,200 feet in the northern part of Santa
Rosa County (fig. 6). Thus, unlike most sedimentary units along the
Gulf Coast, these limestones thin rather than thicken downdip. The
lower limestone is white to grayish cream and is rather soft and chalky.
Well samples contain as much as 30 percent very fine to very coarse
sand, but some of this probably caved from above during drilling. Sam-
ples also contain some gray clay. Lenses of hard light-gray shale occur
within the limestone, but these appear to be randomly distributed and
cannot be correlated from well to well over any great distance. Much of
this limestone consists of foraminifers, corals, bryozoans, ostracods, frag-
ments of echinoids and mollusks, and other fossils. Black phosphatic
grains are locally plentiful.
Much of the Floridan aquifer in Escambia and Santa Rosa counties
is composed of a porous and permeable coquina consisting of fossil
fragments. This aquifer contains substantial quantities of ground water.
Most of the water in both the upper and lower limestones of the Flori-
dan aquifer is confined above and below by beds of relatively imperme-
able clay. Ground water in the lower limestone is also derived mainly
from precipitation that occurs 10 to 35 miles north of the area in
Conecuh, Escambia, and Monroe counties, Alabama, where the lime-
stone crops-out. The movement of water in the lower limestone is gen-
erally to the south and southeast.







FLORIDA GEOLOGICAL SURVEY


F P EXPLANATION
S F Number mcates depth to the top Norml fault
of he Ocala Lnsbone in feet -u U=Upthrown side; D=D nlhfrown side
below mean sea level
Contour represents the top of the
S -"- Ocala L nefoe an feet below Nolte All data from electric logs
mean sea level. Cctour iterval I00 feet.
SI I I I I 6I ,,,,
0- 0 1 2 3 4 5 6 7 9 I Om1 Geolc/ by 0 T Marsh

Figure 9. Map of Escambia and Santa Rosa counties showing contours on top of
the lower limestone of the Floridan aquifer.



AQUICLUDES

Aquicludes within the sand-and-gravel aquifer.-As shown by the
geologic section along the Perdido River in Escambia County (fig. 8),
the sand-and-gravel aquifer contains discontinuous layers and lenses of
clay and sandy clay. The clay strata range in thickness from a few inches
to several tens of feet. For example, the clay bed mined by the Taylor
Brick and Tile Co., Inc., of Molino in Escambia County is about 50 feet







REPORT OF INVESTIGATIONS No. 40


thick. The available data suggest that the clay and sandy clay strata
may range in length from a few feet to several miles.
Another type of relatively impermeable layer within the sand-and-
gravel aquifer is hardpan. This rock, formed by cementation of sand by
iron oxides precipitated from ground water, occurs extensively through-
out westernmost Florida and southern Alabama. This rock ranges in
thickness from a fraction of an inch to 4 feet. Little is known concerning
the lateral extent of these hardpan layers, but it is unlikely that any
layer extends for more than a few thousand yards. Although the rock is
dense, these layers are sometimes filled with many curiously shaped
cavities of uncertain origin. The rock is rust brown and is generally hard,
although some of it is soft. It is composed of iron oxides in the form of
limonite and goethite. Most "rock" on local drillers' logs is hardpan. It is
the only consolidated rock near the surface in westernmost Florida, and
it is occasionally used in the construction of stone walls and buildings.
The relatively impermeable layers of clay and hardpan affect ground
water in several ways. First, they reduce the average permeability of
the aquifer. Second, although ground water in the sand-and-gravel aq-
uifer probably is more or less hydraulically connected, owing to the dis-
continuity of the impermeable beds, these layers (assisted by the hy-
draulic gradient) cause the water beneath them to be under artesian
pressure. Third, where these layers lie at or near the ground surface,
they decrease recharge to the aquifer by reducing infiltration rates and
cause water to be retained in depressions, where it is evaporated. Sev-
eral hundred ponds, large enough to be shown on topographic maps,
dot Escambia and Santa Rosa counties. Considerable inconvenience and
damage is caused in some residential areas by ponding of water above
clay or hardpan layers after heavy rains. In some areas these layers
underlie perched water bodies and thus make small or moderate sup-
plies of ground water available at relatively shallow depths. Finally,
these layers are responsible for countless springs, which are typically
found at the heads of gullies and small box canyons called steepheads.
These canyons are notched into the plateau-like areas that are remnants
of marine terraces of Pleistocene age. Excellent examples of such steep-
heads are found on the Eglin Air Force Base, south of the Yellow River.
Here numerous small streams originate as springs that discharge along
clay or hardpan layers at the steepheads of the gullies. As most of these
springs occur at about the same elevation, 50 feet or so above sea level,
it seems likely that they are emerging along the same relatively imper-
meable layer. The gullies were formed by headward erosion from the
edges of the terraces.







FLORIDA GEOLOGICAL SURVEY


Aquiclude below the sand-and-gravel aquifer.-Two thick clay units
of Miocene age lie between the sand-and-gravel aquifer and the upper
limestone of the Floridan aquifer in the southern part of the area (figs.
6, 10). The observed thickness of this clay ranges from about 150 feet
on Santa Rosa Island near the Santa Rosa-Okaloosa county line to about
980 feet at a location 4 miles west of Pensacola. As shown by the
structure-contour map in figure 10, the upper surface of the thick clay
units generally dips to the southwest. The top of the clay units is only


EXPLANA1ION
Stll Nu.trO, ind-'o ol 0Dh to the. 1,V
Of t Io Mo0tcor Cloy. in Wl
s. u L belCO moon So Jvol
Contour *,psOlnl thy too tf the
.-JO--O M'occOn Cloy, in too bolow
moen Soo lovil
Contour inlotv 00 I flt

0 4 6 10 a, 1 o0.m Ada0 odrOmn 0 T Mortn
Figure 10. Map of Escambia and Santa Rosa counties showing contours on top
of the Miocene clay units.








REPORT OF INVESTIGATIONS No. 40


135 feet below sea level in the area 6 miles northwest of Milton and
1,000 feet below sea level in the southwest corner of Escambia County.
A few miles north of Cantonment, the clay interfingers with the
sand-and-gravel aquifer (fig. 6). The two clay units are separated by a
bed of sand that ranges from 20 to 160 feet thick.
The clay is gray to dark gray and contains much silt, very fine to
coarse sand, and some gravel. It is dated as Miocene on the basis of
mollusks and foraminifers. Apparently, this is one of the units that local
drillers sometimes call the "Blue Marl."
Aquicludes within the Floridan aquifer.-The Bucatunna Clay Mem-
her of the Byram Formation of middle Oligocene age (Marsh, 1962)
separates the upper and lower limestones of the Floridan aquifer and
underlies all of westernmost Florida and parts of Louisiana, Mississippi,
and Alabama. Within the area, the Bucatunna ranges in thickness from
about 45 feet in the northwest corner of Santa Rosa County to 215 feet
just north of Escambia Bay. The Bucatunna rests uncomformably upon
the eroded surface of the lower limestone of the Floridan aquifer and is
overlain conformably by the flat, even base of the upper limestone. The
Bucatunna consists of gray, soft, silty to sand clay containing foramini-
fers, ostracods, and a few mollusks. The unit crops out along a belt that
lies about 10 to 35 miles north of the area in Alabama.
Although much of the Floridan aquifer is porous, it contains zones of
dense rock which may have been caused by solution and re-precipita-
tion calcite. These dense layers serve to prevent or retard movement of
water and thus may be classed as aquicludes.
The lower part of the lower limestone of the Floridan aquifer con-
tains thick but irregular zones of gray, hard, slightly calcareous, silty
clay-shale as much as 300 feet thick. As these zones are near the base of
the aquifer and seem to be continuous, they have relatively little effect
on the water in the limestone. However, they reduce the average trans-
missibility of the aquifer (see p. 160).
Aquiclude below the Floridan aquifer.-The lower limestone of the
Floridan aquifer is underlain everywhere in the area by gray shale and
clay of middle Eocene age. The top of this shale and clay, although slop-
ing generally southwestward, undulates broadly implying that these
rocks were eroded before deposition of the overlying limestone (fig. 4).

REGIONAL DIP
The lack of exposures and observable bedding within the sand-and-
gravel aquifer makes it impossible to obtain the strike and dip of this









FLORIDA GEOLOGICAL SURVEY


unit. However, the top of the Bucatunna Clay Member presents a gen-
erally uniform, easily identifiable surface whose attitude can be com-
puted readily (fig. 11). This surface strikes about N. 65 W. and dips
about 30 feet per mile toward the southwest. The top of the lower lime-
stone of the Floridan aquifer also dips southwestward at 30 feet per
mile and has a strike of N. 60 WV. Probably the sand-and-gravel aquifer
has a gentler dip.


Figure 11. Map of Escambia and Santa Rosa counties showing contours on top of
the Bucatunna Clay Member of Byram Formation.


0 EXPLANATION
f Well A-A'Lf ol 0closs-section in g.r.e 6.
L % -,mat l t W 1 o N m ber i1nd5ote o l hl u ie Dtr ne," t d i
U-Liqhlroon .ao Op as tl 0 op olunn Cofy t. RaF)-d i.L oa d, d mte bp of
DIU D:zC,-*ro- sid Member. i w t men Bucalno Cloy Member
Conour ine tepresnts the aloude d the lop of
the BCatunna Clay Membe4 pn feel helo
Smeon s level Cnour inerl 100 feel.
Geology by O.n t I ot"i







REPORT OF INVESTIGATIONS No. 40


RELATION OF GEOLOGY TO GROUND WATER
MOVEMENT OF WATER
The direction of ground-water flow is determined by the pressure
head from point to point. The head, in turn, is determined by the hy-
drologic, geologic, and topographic conditions between the recharge and
discharge areas. The relative position of rock layers of greatly differing
permeabilities may have an important influence on the direction of
ground-water flow. Owing to the relative impermeable clay unit and
the Bucatunna Clay Member, which dip gently toward the southwest,
one might expect ground water in the Floridan aquifer to move south-
westward in the area. However, the movement of water in the Floridan
aquifer is to the south and southeast. The dip of strata in the sand-and-
gravel aquifer is so slight that ground-water flow in this aquifer is con-
trolled principally by differences in head resulting from local topographic
irregularities.
The location of four normal faults in the Jay area is shown on figures
9 and 11. These faults are extensions of the fault system around Pollard,
Alabama, where the Pollard oil field is located. Oil is produced in this
field from structural traps along the faults and comes from sands in the
Tuscaloosa Formation of Late Cretaceous age at a depth of approxi-
mately 5,400 to 6,000 feet below sea level.
Just how faults affect flow of the ground water is not known but
different resistivity readings on opposite sides of faults, shown by elec-
tric logs, suggest that some salty water may move upwards along faults
in the lower part of the lower limestone of the Floridan aquifer. How-
ever, water wells near the faults are not nearly deep enough to verify
this.

RELATION OF GEOLOGY TO QUALITY OF WATER
Zones of fresh and salty toater.-Most of the water in the sand-and-
gravel aquifer is fresh. The Floridan aquifer, however, contains sub-
stantial quantities of both fresh and salt water. In the northern part of
the area, the uppermost few hundred feet of the lower limestone of the
Floridan aquifer contains fresh water. At depths greater than about
1,200 feet, the water from this limestone is very salty. In the southern
part of the area, the lower limestone contains only very salty water.
Here the relatively impermeable Bucatunna Clay Member serves to re-
tard the vertical movement of water and thus to prevent salt water in
the lower limestone from moving upward and contaminating the fresher







FLORIDA GEOLOGICAL SURVEY


water in the upper limestone. The water in the upper limestone becomes
salty downdip. Although few samples of water from these salt-water
zones are available for analysis, the zones of relatively fresh and salty
water may be distinguished on electric logs. An analysis of more than
60 electric logs was made for this purpose during the present study.
Mineralization and hardness of ground water.-In addition to differ-
ences in salinity, ground water in the sand-and-gravel aquifer and in the
Floridan aquifer differs in amount of dissolved solids and hardness be-
cause of differences in lithology of the two aquifers. As might be ex-
pected, water in the Floridan aquifer (composed mostly of limestone)
is generally harder and more mineralized than water in the sand-and-
gravel aquifer, which is composed principally of relatively insoluble
quartz sand. As ground water percolates through the upper part of the
sand-and-gravel aquifer, it encounters very little soluble material and
remains soft and virtually unmineralized. However, harder and more
mineralized water comes from deeper wells in the sand-and-gravel aq-
uifer that penetrate sediments containing abundant sea shells. The
abundance of ground water remarkably low in mineral content has in-
fluenced several large industries to locate in Escambia and Santa Rosa
counties.
Relation of quality of water to geologic history of the Gulf Coast.-
For millions of years the Gulf coastal area has been slowly subsiding,
forming a vast sinking trough, or geosyncline. As the trough sank,
streams emptying into the Gulf of Mexico kept the trough nearly full
by dumping into it huge quantities of mud, sand, and gravel. According
to Howe (1936, p. 82), "These sediments have been concentrated along
a narrow zone paralleling the present shore, and, since the beginning of
the Eocene, have accumulated to a thickness which probably exceeds
30,000 feet [south of the Mississippi River] the region of the pres-
ent coastline has been depressed under the weight of these deposits to
almost three times the present maximum depth of the Gulf of Mexico.
The major axis of the Gulf Coast geosyncline approximately parallels
the Louisiana coastline "
Ground water in the Floridan aquifer in the Florida Peninsula be-
comes mineralized as it moves through soluble limestones. In Escambia
and Santa Rosa counties, however, these limestones have been depressed
hundreds of feet by the sinking of the Gulf Coast geosyncline. This
circumstance made it possible for rivers and streams to deposit the del-
taic sand and gravel which make up the principal ground-water aquifer
in westernmost Florida. The main area of subsidence did not extend far
enough to the east to depress the limestones of peninsular Florida.







REPORT OF INVESTIGATIONS No. 40


SURFACE WATER
Escambia and Santa Rosa counties have an abundant supply of sur-
face water of excellent quality flowing in the streams and additional
supplies are found in small natural ponds and a few man-made ponds.
Streams are the main source of fresh surface water, discharging an aver-
age of 8.5 bgd into the bays along the southern boundary of the counties.
Small reservoirs created by dams are few in number at present. How-
ever, much of the terrain lends itself well to the development of small
reservoirs, and more will probably be built as the economy of the area
expands. The bays along the coast cover more than 230 square miles and
provide excellent facilities for boating, fishing, swimming, and shipping.
The streams that flow into Escambia and Santa Rosa counties or
along their boundaries drain about 6,000 square miles before reaching
the counties. An average of slightly more than 10,000 cfs (cubic feet per
second), or 6.5 bgd, is brought into the counties by the surface streams.
Streams within the two counties pick up an average flow of 3,100 cfs, or
2.0 bgd, from the 1,700 square miles of land of the area.
The flow of 2.0 bgd that is derived from within the two counties is
equivalent to 25 inches, or 40 percent, of the 63-inch annual rainfall of
the area. The combined losses by evaporation, transpiration, and under-
ground flow averages about 38 inches per year.
Average unit runoff varies from basin to basin from 14 inches to 50
inches. The map in figure 12 shows approximate average annual runoff
in inches from stream basins within the two counties.
Runoff during an extremely wet year is about 2% times that for a
dry year. Figure 13 shows runoff in inches for 1956, a year of low runoff,
and for 1961, a year of high runoff. The 1956 rainfall was near normal
but the low runoff for that year reflected the rainfall conditions during
the two previous years, which were well below normal. The cumulative
deficiency of rainfall for the 3-year period 1954-56 was about 40 inches.
This 3-year deficiency in rainfall reduced the amount of direct surface
runoff and caused a decline in ground-water levels which in turn caused
a decline in the base flow of streams. Streams in this area have a high
rate of base flow that comes as seepage from the ground.
The surface waters of Escambia and Santa Rosa counties are of ex-
cellent quality, except in the coastal reaches where tides bring salt wa-
ter up the streams. The Escambia River coming out of Alabama brings
water of higher mineral content (about 100 ppm, parts per million);
however, this mineralization is diluted somewhat by the lower mineral-
content waters of the Florida tributaries.







FLORIDA GEOLOGICAL SURVEY


Figure 12. Approximate average annual runoff, in inches, from areas within Escambia
and Santa Rosa counties.


Most of the streams of the two counties originate in the highlands
and flow in sand and gravel-lined streambeds. The low solubility of the
sand and gravel results in water of very low mineral content, generally
less than 30 ppm. The mineral content varies seasonally. During the
rainy season the minerals in the water are diluted, but the color gen-
erally increases because of surface runoff. In the dry season the water
has a slightly higher mineral content, but very little color.
The quality of available surface water in the area varies from place
to place and from time to time. The seasonal fluctuations follow very
closely the pattern of rainfall. The discussion that follows is concerned
with the availability of surface water with respect to quantity and







REPORT OF INVESTIGATIONS No. 40


quality within the two-county area. Where possible, short-term records
were extended to long-term periods to obtain average flow figures and
flow-duration curves. Streamflow characteristics are discussed by basins
as outlined in figure 14.


Figure 13. Runoff in inches for 1961, a year of high runoff, and for 1956, a year of
low runoff, from areas within Escambia and Santa Rosa counties.

COLLECTION OF DATA
Streamflow data were collected at only four sites in Escambia and
Santa Rosa counties prior to 1958. The first stream gaging station was
started on the Escambia River at Century in 1934. In 1938 a station was.
established on Big Coldwater Creek near Milton, and in 1941 one was.







FLORIDA GEOLOGICAL SURVEY


Figure 14. Basin map of Perdido, Escambia, Blackwater, and Yellow rivers.

started on Perdido River at Barrineau Park. The collection of river
stages on the Escambia River near Gonzalez was started in 1951 and
streamflow records on Pine Barren Creek near Barth were started in
1952. Streamflow data were also collected at two nearby sites, Yellow
River near Holt (1934-1940) and Escambia Creek at Flomaton, Ala-
bama (1939-1951).
At the start of the present investigation in 1958, additional data-
collection sites were established to define streamflow conditions and to
determine in more detail the quantity and quality of the water supply
in the area. A list of data-collection sites and the length of record at each
site are given in figure 15. The map in figure 16 shows the location of
these sites.










REPORT OF INVESTIGATIONS No. 40


S STATION A.MA.
q. nl.

I B'you MPrcua Crook nonr I'an acola, la. 11.2

2 l1.Coldwator River near HMlton, Fla. 237

) nig Juniper Crook near Harold, Fla. 1l2

I Plf Junlpor Crook near Munnon, Fll. 36

5 plackvater River neor Holt, Fla. 276

6 BIrushy Creek near Walnut 11111, Fla. 49

' CNoo Crook nenr lPlurr Springa, Fa.

0 Carpenter Creek nonr Pononcola, Fin. .31 l

9 ftat Fork Coldvater Crook naor Munaon, Fin. 6I

10 klevoenile Crook near Fnoloy, Fla.

11 EacI bial Crook at Floiaton, Ale. 325

12 Ecam bl l River noar Century, Fla. 3,817

13 Kacmbia River near Gonzoloz, Fla. -

11I goeabia River near Molino, Fla.

15 Hurricane Branch near Milton, Fla. 2.95

16 Jacks Branch near Muocoge, Fla. 23.2

17 McDavid Crook near Barrineau Park, Fla 26.5

10 Moore Creek near Chumucklo, Fla. 22.0

19 Perdido River at Barrineau Park, Fla. 39

20 Perdido River near Nokomsi, la. -

21 Pine Barren Crook near lBrth, Fla. 75.5

22 Pond Crook near Milton, Fla. 58.7

2 Svootweter Crock near Mun=on, Fla. '5

24 Weat Fork Coldvator Crook at Cobbtown, Fla. ?9.5

25 Yellow River near lolt. Fla. 1,210


mo Streoamlow, stage Chescal aalyse

Figure 15. Graph showing periods and types of surface-water records in and near
Escambia and Santa Rosa counties.


FLOW-DURATION CURVES

Daily streamflow data are available at 10 sites with 4 to 27 years of

record. Escambia River near Century has the longest record. Records

from 9 of these stations were extended to the 27-year period, and figures







FLORIDA GEOLOGICAL SURVEY


of average flow and flow-duration curves were obtained from these ex-
tensions. The flow-duration curves and average flows for the 10 stations
are given in figures 17 and 18.


-,w' I- M W iof 0 ir@ I 4w w
Figure 16. Map of Escambia and Santa Rosa counties showing surface drainage and
data-collection points.

PERDIDO RIVER BASIN
OCCURRENCE OF WATER
The Perdido River, the westernmost stream in Florida, forms the
part of the boundary line between Florida and Alabama. The part of
the basin in Florida lies in a narrow band, 5 to 10 miles wide, along the
eastern side of the main channel in Escambia County. The four major
tributary streams on the Florida side of the river are Brushy Creek,
Boggy Creek, McDavid Creek, and Jacks Branch. Elevenmile Creek and











REPORT OF INVESTIGATIONS No. 40


GAGING STATION
.....L Brushy Creek near
Wolnut Hill, Fla.
_- 2 Escombla River near
Century, Flo,
- -&J.ocks Branch near
Muscogee, Fla.
.. 4,Perdldo River near
Barrlneou Park, Flo,
....... 5 Pine Barren Creek
near Barth, Flo,


DRAINAGE
AREA
SO. MI.
49

3817

23.2

394

75.3


AVERAGE FLOW FOR
27-YEAR BASE
PERIOD, 1934-61,CFS
95

6151

24

756

159,


001 0.05 02 0.5 1 2 5 10 20 30 4050 60 70 80 90 95 98 99995 99.9 99.99
PERCENT OF TIME DISCHARGE EQUALED OR EXCEEDED THAT SHOWN

Figure 17. Flow-duration curves for 5 streams in Escambia County.










32 FLORIDA GEOLOGICAL SURVEY



Bayou Marcus Creek flow into Perdido Bay and are included in the

discussion of the Perdido River basin.

The basin, outlined on the map in figure 14, covers 925 square miles.

Of this area, 236 square miles are in Escambia County, Florida. Streams


DRAINAGE
GAGING STATION AREA
SQ. ML
- -L Big Coldwoter Creek
never Mllion, Fml. 237
---2.Big Juiper Creek
near Munaon. Fla. 36
-...-. ackwoter Ri;ver
nesa Baker, Fil. 205
........4.Pond Creek pnar
M;ilon, Fla. 58.7
- S West Fork 81i Coldwater
Creek aor Cobbtoln, Fla. 315


AVERAGE FLOW FOR
27-YEAR BASE
PERIOD, 1939-61, CFS
534

65

320

78

.74


I














~II
; o -- -- ------ --- ----- --- -- -- ---







1,000




ioo
\
















lot
ZO- 0 0 0 0 -
\," i. .
1 ".. "






o~ ~ ~ .. .


90 95 98 99 99.5 99.9


PERCENT OF TIME DISCHARGE EQUALED OR EXCEEDED THAT SHOWN

Figure 18. Flow-duration curves for 5 streams in Santa Rosa County.


30,000


20.000 --


,,' "


to 00(


s



3


acOt 0.05a 02 O.S


za 30 40 so 60 70 80


99.99


--








REPORT OF INVESTIGATIONS No. 40


in the basin drain very hilly country. The hills are from 100 to 150 feet
above the stream valleys. The fall of the Perdido River streambed from
the Alabama-Florida State line to Muscogee is 150 feet for a channel
length of about 40 miles. The fall from Muscogee to Perdido Bay is 15
feet for a channel length of about 20 miles (taken from U.S.G.S. topo-
graphic maps).
Tidal fluctuations occur in the lower reach of the river. During
periods of low flow, tidal effects extend about 15 miles upstream from
Perdido Bay nearly to Muscogee. Tidal effect will extend the greatest
distance upstream during periods when the river is low and the tides
are at seasonal highs. The salt front, however, does not extend as far
upstream as the tidal effect.
The downstream, 10-mile reach of the main channel is generally
more than 10 feet deep, with holes extending to 45-feet depths. A depth-
profile graph of the lower 10 miles of the river is given in figure 19.






14 mli
13.m. Omi. (Mouth) ay









S--250--CSlitd. cu.lul; i p1 p. .14.
Iemi. mi.







9 --. 4- M. - --lo


-W e r
5. b.9n~


Figure 19. Channel-bottom profile of lower Perdido River.







FLORIDA GEOLOGICAL SURVEY


This depth-profile graph was obtained from a sonic depth-recorder mov-
ing along the centerline of the channel. The water-surface elevation in
the lower reach of the river during low stages fluctuates with tide from
about 0.5 to 1.5 feet above mean sea level.
Throughout its length the Perdido River channel is tortuous. The
low-water channel in the vicinity of Barrineau Park is about 150 feet
wide and winds through a thickly wooded flood plain that is half a mile
wide. The streambed is composed of sand and gravel and characterized
by alternate sandbars and holes.
The steep slope of the drainage basin causes high rates of direct run-
off. Consequently, floods in this basin are usually of short duration. A rise
in water level of 15 feet is not uncommon at Barrineau Park. The highest
flood of record reached an elevation of 51.5 feet above sea level in
March 1929. The usual low-water stage is 28 feet above sea level. Dur-
ing the flood of April 1955, which was the highest in the 20-year period
ending in 1961, the river reached a peak flow of 39,000 cfs at an eleva-
tion of 49.7 feet above sea level at the Barrineau Park gaging station.
Three days after this flood peak the stage had receded 17 feet and the
river was within its banks.
The consideration of floods and their effects on the area is an essen-
tial item in planning developments adjacent to the stream channel. The
probability of future floods can be predicted on the basis of floods that
have occurred in the past. From a study of the magnitude and frequency
of past floods, a means of estimating the frequency of floods has been
developed for Florida (Pride, 1958). Regional flood-frequency curves
applicable to this area have been developed from this report and are
presented in figure 20.
The sustained low-flow yield of the streams should be examined in
considering an area for development. If the minimum flow of a stream
during a reasonably long period of time is known to be above the an-
ticipated demand, the supply is adequate without storage. However, if
the minimum flow falls below the anticipated demand, either of two
measures can be undertaken. Storage reservoirs can be built to store
water during periods of excess flow for use during periods of deficient
flow; or, if the deficient flow is of short duration and occurs infrequently,
the use of water might be geared to the available supply.
The low-flow frequency curves given in figure 21 for Perdido River
at Barrineau Park, Florida, show the frequency of average flows for the
indicated periods. For example, a discharge of 250 cfs will occur as a
1-day average once in 2.4 years, or as a 30-day average once in 6.5 years.
The Perdido River basin yields copious quantities of water. The av-








REPORT OF INVESTIGATIONS No. 40


erage runoff at Barrineau Park is 26.0 inches per year. That is, the
average flow of 756 cfs for 1 year would cover the drainage area of 394
square miles to a depth of 26.0 inches. This is in comparison with the
State average runoff estimated to be 14 inches per year (Patterson,
1955). The high yield of the Perdido River basin can be attributed to
two factors: (1) a high annual rainfall-this area receives about 63
inches per year; and (2) the coarse sand and gravel surficial covering
that releases water to the streams as seepage from the water table or as
artesian flow from local aquifers.


200,000


100,000


50,000


10,000


5000


cn 2000 1-I 1 1 1-
50 o o00 500 10000 50o 10,000
DRAINAGE AREA, IN SQUARE MILES
Figure 20. Regional flood-frequency curves for the Perdido, Escambia, Blackwater,
and Yellow rivers.

The pattern of flow with respect to time is similar to that of rainfall.
March and April are by far the months of highest runoff, and October is
the month of lowest runoff. The bar graphs in figure 22 show the aver-
age, maximum, and minimum monthly discharges for the Perdido River
at Barrineau Park for the 20-year period 1941-61.
The flow-duration curve for Perdido River is given in figure 17. The
slope of this curve indicates the variability of flow. This stream has high







FLORIDA GEOLOGICAL SURVEY


flood flows, and relatively stable flows during medium and low-water
periods.
The average flow from the entire Perdido River basin is estimated to
be 1,730 cfs. About one-fourth of this, or 440 cfs, is derived from the
area lying within Escambia County.


800




700



600




500



400



300



200


100
O-


Drainage area: 237 sq. mi.
Average flow: 534 cfs.





LOW-FLOW FREQUENCY
Example: For a 20 year recurrence
interval the I-day minimum
flow is 160cfs and the 12-
S month minimum flow is
310 cfs.
-. v ^ rrim
---- ^ ^ -- ^ :-- -- -- --


Month

Month

Month
Month
IMonth
Day
I Day


12

6

4
2
-


105 1.1


20 30 40 50


RECURRENCE INTERVAL, IN YEARS
Figure 21. Low-flow frequency curves for Perdido River at Barrineau Park, 1941-61.


Brushy Creek, entering the Perdido River 13 miles above Barrineau
Park, drains 75 square miles-53 square miles in the extreme northwest
corner of Florida and 22 square miles in southern Alabama. At the gaging
station near Walnut Hill, the long-term computed average flow was 95
cfs from the drainage area of 49 square miles. The average flow from the
entire basin is estimated to be 140 cfs, of which about 100 cfs comes
from Escambia County and about 40 cfs from southern Alabama. The 4
years of streamflow records on Brushy Creek were adjusted to long-term


' ` ' '


)I









REPORT OF INVESTIGATIONS No. 40


J F M A M J J A S 0 N D


Figure 22. Graph of the minimum, average, and maximum monthly discharge of the
Perdido River at Barrineau Park, 1941-61.


2600





2200



2000



1800

MAXIMUM

1600 -



1400



1200 -- -- __





AVERAGE
800



6000 -
600 -- .... : --MINIM M
S:: : ." -M- M-INIMUM

n0- __ -


I







FLORIDA GEOLOGICAL SURVEY


records on the basis of 27 years of records for Escambia River near Cen-
tury. The flow-duration curve given in figure 8 was also adjusted on the
basis of this long-term station.
Boggy Creek drains an area of 27 square miles. Based on unit runoff
per square mile of nearby streams, the average flow of Boggy Creek is
estimated to be 50 cfs.
McDavid Creek drains 34 square miles in Escambia County and
flows into the Perdido River a mile above Barrineau Park. The average
unit runoff from this basin is estimated, on the basis of discharge meas-
urements and correlation with records of nearby basins, to be 1.9 cfs per
square mile, giving a total flow from the basin of 65 cfs.
Jacks Branch, a tributary entering the Perdido River west of Canton-
ment, has the lowest runoff of any stream gaged in the Perdido River
basin. The average unit runoff was computed to be 1.0 cfs per square
mile. The Jacks Branch basin covers 24 square miles and produces an
average flow of 24 cfs. The minimum daily flow measured at the gaging
station is 3.0 cfs, or 0.13 cfs per square mile. The flow-duration curve
given in figure 17 has a greater slope than that for other streams in the
area and shows the flow of Jacks Branch to be more variable.
The low yield of Jacks Branch, as compared with other streams in the
area, is a result of unusually low base flow or seepage to the stream.
Only about 30 percent of the total runoff is base flow, whereas the base
flows of other streams comprise from 55 to 75 percent of the total. Direct
surface flow, or overland flow, of Jacks Branch is about the same as other
streams, based on a unit area comparison. The average annual runoff of
Jacks Branch is 14 inches.
Elevenmile Creek drains into the north end of Perdido Bay and is
used for industrial waste disposal.
Bayou Marcus Creek drains 25.9 square miles along the northwestern
outskirts of Pensacola and empties into the northeast corner of Perdido
Bay. Two years of records were collected at a gaging station located at
U.S. Highway 90 prior to construction of a dam in February 1960. The
dam created a reservoir of about 60 acres above State Road 296, about
two miles upstream from the gaging station.
An average annual flow of 43 cfs was measured at the gaging station
from a drainage area of 11.2 square miles. This unit runoff of 3.8 cfs per
square mile is the highest unit runoff within the two counties. The aver-
age runoff from this small area is about 50 inches per year, or 80 percent
of the average annual rainfall. This high runoff is probably derived from
large rates of ground-water inflow from areas outside the surface drain-
age divide.







REPORT OF INVESTIGATIONS No. 40


MINERAL CONTENT
The Perdido River and tributaries contain water of very good quality.
The highest mineral content of 52 ppm was recorded at Barrineau Park
where daily water samples were collected for one year. The mineral
content varies with streamflow. During high flows the mineral content
is lower because of dilution; however, during this same period the color
increases because of surface runoff. The color is the most objectionable
characteristic to potential industry because it is harmful to many proc-
esses and difficult to remove.
Elevenmile Creek contains the water of poorest quality in the two-
county area. Samples collected from Elevenmile Creek on a semiannual
basis have shown the mineral content to range from 392 to 914 ppm and
color from 500 to 1,250 units. This stream has been contaminated by in-
dustrial wastes; however, recent corrective measures have been taken to
clean it up.
On September 20, 1961, a chloride profile was made on Perdido
River. The salt front was followed with a specific conductance meter to
the point of furthest intrusion (see fig. 19). When the movement up-
stream of salt water halted a top to bottom profile was made at 2-foot
intervals. This was quickly followed by a series of profiles at various
points downstream.
On this particular day the salt extended a little over 63 miles up-
stream from the mouth. The flow of the river on this day is exceeded
about 50 percent of the time indicating the salt would probably extend
further upstream about 50 percent of the time.

ESCAMBIA RIVER BASIN
OCCURRENCE OF WATER
The Escambia River is the largest single source of surface water
within the study area and is the fifth largest source in the State. The
basin as outlined in figure 8 covers 4,233 square miles, of which 410
square miles are in Florida. The main channel starts near Union Springs,
Alabama, as the Conecuh River, and flows southwestward to the
Florida-Alabama line near Century, Florida. Near the State line the
name changes to Escambia River. The Escambia River flows southward
and empties into Escambia Bay north of Pensacola.
The average flow from the Escambia River basin is estimated to be
7,000 cfs. The average flow from the 410 square miles of the basin in
Florida is estimated to be 860 cfs. The average unit runoff at the Cen-
tury gaging station, drainage area 3,817 square miles. is 1.6 cfs per






FLORIDA GEOLOGICAL SURVEY


square mile. The average unit runoff from gaged tributaries in Florida
(Pine Barren Creek and Moore Creek) is 2.1 cfs per square mile.
The lower part of the Escambia River exerts a major influence on
the two-county area, not only because it serves as a source of water sup-
ply but also because of its size and location with respect to the fast de-
veloping industrial area around Pensacola. The lower basin is about 9
miles wide. The river channel is tortuous and winds through a low,
swampy flood plain about 3 miles wide. Several estuarine channels ex-
tend into the flood plain from Escambia Bay. Farther upstream two
islands within the flood plain are exposed during periods of low river
stages.
Flow in the lower river basin is affected by tide to a point north of
Brosnaham Island. The change in stage due to tide effect at the north
end of the island was 1.8 feet during a series of flow measurements
made on August 24, 1954, but the direction of flow does not reverse at
that point. A tide range of 2.5 feet is not uncommon near the nylon plant
of the Chemstrand Corporation. An observation of flow conditions made
near the Chemstrand plant on October 22, 1952, showed the flow to re-
verse at that point.
Soundings along the centerline of the lower channel, made by use of
a sonic depth-recorder, showed the deepest part of the channel to be
about 50 feet at a point 5 miles upstream from Escambia Bay. A depth-
profile graph made from these soundings is given in figure 23. Deep
holes in the channel, such as that 5 miles upstream from the river mouth,
trap salt water that can be a source of contamination of surrounding
ground-water supplies if heavy pumping from wells near the river is
carried on for long periods of time.
The tributaries below Pine Barren Creek are short and drain small
areas. The ridges forming the drainage divides vary in elevation from
150 to 200 feet above sea level. The Escambia River flood plain slopes
from about 15 feet above sea level near the mouth of Pine Barren Creek
to sea level at Escambia Bay.
The larger streams in the Escambia River basin with watersheds in
Florida are Pine Barren Creek, Canoe Creek, and Moore Creek.
Pine Barren Creek drains an area of 98.1 square miles, 85 square
miles of which is in Escambia County, Florida. The headwaters of the
creek are near the town of Atmore, Alabama, 2 miles north of the state
line. The average yield of Pine Barren Creek is 28.6 inches per year,
which is about 45 percent of the rainfall on the basin. A very substantial
base flow of 60 cfs (38.8 mgd) has been measured from the area of
75.3 square miles above the gaging station. The magnitude of flow will







REPORT OF INVESTIGATIONS No. 40


be different at any other point in the basin. Based on a flow measure-
ment of a tributary entering just below the gaging station, it is assumed
that the magnitude of flow at any point in the basin is proportional to
the size of the area drained above that point.
The average flow from the Pine Barren Creek basin is estimated to
be 207 cfs, of which about 28 cfs comes from Alabama and 179 cfs from
the drainage area within Escambia County, Florida. About two-thirds of
the total streamflow is base flow or seepage, and one-third is direct run-
off from overland flow.


Su.r m.d. by d~plh
ncordr Au9.22,1961


-250- Chloride t ont oA. 2219
--250-- Chloride oltean!. in parts per inmocl


Figure 23. Channel-bottom profile for lower Escambia River.

The length of the Perdido River basin is about six times the width.
This elongated shape and the steep topography of the basin produce a
short time of concentration of runoff. Rain anywhere on the basin has to-
move only a short distance before reaching the main channel. The steep.
valley slope of the main channel allows this water to flow at high veloci-
ties to the Escambia River. The channel-bottom profile of Pine Barren
Creek is given in figure 24. This channel has an average slope of more
than 10 feet per mile.
The fast-changing rates of flow during floods in this basin can be
visualized more clearly by comparing an average flow for a day with the
momentary peak flow. The mean daily flow for April 14, 1955, was 9,46(0







42 FLORIDA GEOLOGICAL SURVEY

cfs and the peak flow on the same day was 24,800 cfs-over 2% times
greater.
The flow-duration curve for Pine Barren Creek given in figure 15
shows the percent of time a specified discharge has been equaled or
exceeded. For example, the mean daily flows at the gaging station were


CHANNEL DISTANCE ABOVE SOUTH, IN MILES


Figure 24. Channel-bottom profile of Pine Barren Creek.


greater than 67 cfs (43 mgd) for 98 percent of the time. If an industry
needs a water supply of 43 mgd, a deficiency 2 percent of the time might
be tolerated if it were uniformly distributed, with only a few days of
deficient flow in any continuous period. A deficient flow of 2 percent of
the time, on the other hand, could prove disastrous if it came in a con-
tinuous period of several months duration.
The data given in figure 25 are helpful in determining probability
of length of periods of deficient flow. The lowest average flow for a
specified period can be determined from the lower curve in figure 25.


-00 -- --



,r -- -- -- -/- -
,I. _. ___ I __ -



S ___


S Spe.g5ophic map.

2) '
-f rr----


0o
2 4 10 12 14 as t 20 22 24 26


i








REPORT OF INVESTIGATIONS No. 40 43


For example, the lowest average flow for a 1-month period was 60 cfs
(38.8 mgd). The upper curve shows the longest period of time that a
specified flow was deficient. The curve shows, for example, the longest
period that the flow was 60 cfs or less was 10 consecutive days.
The curves shown in figure 25 can be used to determine if the flow


10,000
8000 -
6000
5000

4000 -
4000 Maximum period
2000 of deficient flow


1000
800 -
600 -
400
300

200


100
80
60
50

30 Lowest average flow
n for indicated period
20 -


S 2 23 568 1 24364872
1 2 3 4 6 8 10 20 1 2 3 4 56 8 12 18 24 36 48 72


CONSECUTIVE DAYS


CONSECUTIVE MONTHS


Figure 25. Discharge available without storage, Pine Barren Creek near Barth,
1952-61.


is sufficient for a particular use without storage. If storage is needed, the
amount of storage required can be determined from the mass-flow curve
given in figure 26. The volume of water required in a reservoir can be
determined by superimposing a line representing the required rate onto
the mass curve at such a position as to give the maximum distance be-
tween mass curve and the flow-required line. The maximum distance
represents the amount of storage required, excluding losses by evapora-
tion and seepage.








FLORIDA GEOLOGICAL SURVEY


20<


280



260



240


Storage required
12,000 cfs-doys


NOTE* No allowance mode for
evaporation and seepage
losses. |


0





0

Storage required
8500 cfs-days




0




0/



0

0






1952 1953 1954 1955 1956 1957 1958

Figure 26. Mass-flow curve for Pine Barren Creek near Barth, 1952-58.


18(



16<



14(



12(



10'






REPORT OF INVESTIGATIONS No. 40


The Moore Creek watershed covers 32 square miles in Santa Rosa
County. The flow from this creek enters the Escambia River just up-
stream from Pine Barren Creek. The yield from this basin is estimated to
be approximately the same as Pine Barren Creek basin, about 29 inches
per year. Average flow from the basin is estimated to be 67 cfs.
Canoe Creek lies mostly within Escambia County, Florida, with its
headwaters in Alabama-24 square miles in Florida and 13 square miles
in Alabama. The channel bed is lined with sand and gravel, and the
banks are steep and heavily wooded. Based on a field observation of the
physical characteristics of Canoe Creek basin, it appears that the flow
characteristics are similar to those of Pine Barren Creek. An average
flow of 78 cfs for Canoe Creek is obtained by multiplying the drainage
area by the unit runoff of 2.1 cfs per square mile for Pine Barren Creek.
The drainage area of the Escambia River at the Century gaging
station is 3,817 square miles. The river above the Century gaging station
is called the Conecuh River in Alabama. Its basin is slightly elongated
in shape, with the longer axis lying in a northeast-southwest direction.
The Conecuh River is located along the southern edge of the basin. All
of its large tributaries have their headwaters along the northern edge of
the basin and flow southward to the Conecuh River.
The seasonal distribution of flow at the Century gaging station, al-
though from a large area located in Alabama, follows a pattern similar
to that of the smaller nearby streams in Florida. The bar graph in figure
27 shows the seasonal distribution of flows for a 27-year period at the
gaging station at State Highway 4 near Century. The highest average
flows occur in March and April and the lowest flows occur in September,
October, and November. The variation 'of flows for any month can be
great. January has the greatest variation of monthly mean flows, varying
from a low of 1,900 cfs to a maximum of 31,500 cfs. October has the low-
est variation of monthly mean flows ranging from 666 cfs to 7,530 cfs.
Some streamflow characteristics for the 27-year period of record at
the Century gaging station are indicated by the flow-duration curve in
figure 17. Based on the flow-duration curve, the flow has been below
1,000 cfs (646 mgd) for only 3 percent of the time. The maximum flow
during the 27-year period ending in 1961 was 77,200 cfs, and the mini-
mum flow recorded was 600 cfs (388 mgd). The computed peak dis-
charge for the flood of March 1929 was 315,000 cfs. The elevation of this
flood peak was 66.1 feet above sea level which was 4.5 feet above the
floor of the bridge. Regional flood-frequency curves for the Escambia
River basin are given in figure 20.
The average yield per unit area from the Escambia River basin ap-


45








FLORIDA GEOLOGICAL SURVEY


I J I F I M I A I M I J I J A 1 S 1 0 1 N I D I

Figure 27. Graph of the minimum, average, and maximum monthly discharge of the
Escambia River near Century, 1935-61.


32.000


zoo







REPORT OF INVESTIGATIONS No. 40


pears to be about the same throughout the basin. Based on records of
the eight gaging stations that are located throughout the basin, the av-
erage yield is about 21 inches per year, ranging from a low of 18.3 inches
to a high of 28.7 inches. The flows measured at these stations came from
drainage areas ranging in size from 75.3 to 3,817 square miles. The
average yield at the Century gaging station was 21.9 inches per year.

MINERAL CONTENT
The Escambia River passes through the outcrop area of the Floridan
aquifer in southern Alabama and dissolves minerals from these lime-
stones. The water of the Escambia River near Century has a mineral
content ranging from 47 to 101 ppm. This is generally considered to be
low mineralization, but compared to the waters of other streams in
Escambia-Santa Rosa counties, it is high. This mineralization is diluted
by the flow from the tributaries that empty into the Escambia River. A
semiannual station located on the Escambia River near Quintette shows
a maximum dissolved solids of 60 ppm. The extent of the salt water
wedge in the tidal reach of the river is dependent on the flow of the
river and the height of the tide in Pensacola Bay. During periods of high
tides and low flows, the salt water extends upstream just beyond the
Chemstrand plant (see figs. 23, 28).
In the last 3 months of 1959 the flow in the Escambia River at Cen-
tury was high and as shown by the graph in figure 28 the chloride at the
Chemstrand plant was low. During the last 3 months of 1960 the situa-
tion was entirely different. The flow at Century was low and the chloride
at the Chemstrand plant was high. On November 22, 1960, the flow at
Century was 1,550 cfs (equaled or exceeded 90 percent of the time)
and the chloride at Chemstrand was 1,454 ppm. On August 22, 1961, a
chloride-profile run on the Escambia River (fig. 23) showed that the
salt front extended about 3& miles upstream. On this day the flow at
the Century gaging station was 2,380 cfs, (equaled or exceeded 70 per-
cent of the time).
The tributaries of the Escambia River originate in highland regions,
the major recharge areas for the sand-and-gravel aquifer. Surface water
in these tributaries is very low in mineral content and generally is very
clear. However, color increases due to contact with organic material
during periods of high flow.
Silica and color could be the two objectionable constituents in the
Escambia River. Silica ranges from 5 to 21 ppm and color ranges from
4 to 120 platinum-cobalt units. The quantity and quality of the waters of
the Escambia River basin make it a good potential source.









FLORIDA GEOLOGICAL SURVEY


1400 ------ 14000


FClw ---



S ,

1000 10000

S I : 0




4 0' I 0' 0 00
'
:0, ,
I








200 2000
.. i
P-


OCTOBER 1 NOVEMBER DECEMBER


2 z



12oo 0ooo
o I ,
2 100 10000





ur i E C t
W 800 .-













strand plant to streamflow at State Highway 4 near Century, October-December 1959
an600 October-D r 000
400 -0



zoo 2000



N 0 20 10 4 10 203 0
OCTOBER NOVEMBER DECEMBER

Figure 28. Relation of daily chloride content in water in Escambia River at Chem-
strand plant to streamflow at State Highway 4 near Century, October-December 1959
and October-December 1960.


10 23


D I0 20


I 10 20 3C






REPORT OF INVESTIGATIONS No. 40


BLACKWATER RIVER BASIN

OCCURRENCE OF WATER
Blackwater River heads in southern Alabama, north of Bradley. The
river enters Florida north of Baker, flows across the northwestern corner
of Okaloosa County, and winds southward along the Santa Rosa-Okaloosa
county line for a distance of about 4 miles. At Bryant Bridge at the
county line, the river turns to the southwest and is joined by Big Juniper
Creek and Big Coldwater Creek, and then continues toward Milton. At
Milton it turns southward and flows into Blackwater Bay.
The shape of the Blackwater River basin and the pattern of drainage
are similar to those of the Escambia River basin, in that the main chan-
nel parallels the eastern and southern edge of the basin and all major
tributaries enter from the north. The basin is well dissected by tortuous
stream channels that wind their way through a thick forest of pine and
juniper trees. Except during floods, the water is clear and flows in clean
channels of sand and gravel.
The following discussion of streamflow is by tributary basins, pro-
ceeding upstream in the following order: Pond Creek, Big Coldwater
Creek, Big Juniper Creek, and upper Blackwater River.
Pond Creek drains an area of 88 square miles, all within Santa Rosa
County. The creek flows southward and empties into the Blackwater
River just south of Milton. The basin has an elongated shape with rela-
tively short tributaries that drain directly from the steep hills. The land
along the basin divide is flat and is from 1 to 2 miles wide. From the
flat divide, however, the land slopes steeply to the stream channel.
Pond Creek has two channels within the lower three-fourths of its
flood plain. One of these is the natural channel which is very crooked
while the other is a straight channel dug many years ago for transporting
logs. The valley slope is steep (fig. 29) with a total fall of about 200 feet
from the headwaters to the mouth, a distance of 24 miles.
The estimated unit runoff from Pond Creek is 1.4 cfs per square mile,
which is equivalent to an average flow of 123 cfs from the basin. The
minimum daily flow measured at the gaging station during a 4-year
period ending 1961 was 43 cfs, or 0.7 cfs per square mile. About 75 per-
cent of the total flow is derived from the ground as base flow and 25
percent is direct runoff by overland flow.
Big Coldwater Creek is the largest tributary feeding the Blackwater
River. The total area drained by this tributary is 241 square miles, of
which 228 square miles are in Santa Rosa County. All except the smallest







FLORIDA GEOLOGICAL SURVEY


streams in the Big Coldwater Creek basin have perennial flows. The
average flow from the basin is estimated to be 542 cfs, of which 517 cfs
come from the drainage area within Santa Rosa County.
The unit runoff of East Fork and West Fork, the two main tributaries
of Big Coldwater Creek, is slightly lower than that of the main creek.
The unit runoff from the upper 64 square miles of East Fork is 2.0 cfs
per square mile; that from the upper 39.5 square miles of West Fork is
1.9 cfs per square mile; and that from the 237 square miles above State


75
s0
30


VALLEY DISTANCE ABOVE MOUTH,


IN MILES


Figure 29. Channel-bottom profile of Pond Creek.


Highway 191, below the confluence of the two forks, is 2.2 cfs per square
mile. The intervening drainage area of 133.5 square miles between the
two gaging stations on the forks and the gaging station on State High-
way 191 has a unit runoff of 2.5 cfs per square mile. About 60 percent
of the flow of West Fork Coldwater Creek is base flow and 40 percent
is direct runoff from overland flow.
Streamflow records have been collected for 23 years (1938-61) on
Big Coldwater Creek. The gaging station near Milton is located on State
Highway 191 and measures flow from 237 square miles. The flow-dura-


-1-- ----


02-4--62
0 2 4 6 a 10 12 14 is is 20 22 24 ef


3







REPORT OF INVESTIGATIONS NO. 40


tion curve for Big Coldwater Creek in figure 16 shows some streamflow
characteristics at this point. Because of the rolling topography and steep
slope of the basin, flood waters drain rapidly. Ground-water seepage
sustains the base flows at rather high rates during dry weather.
A useful arrangement of data is the group of low-flow frequency
curves given in figure 30. They show what the lowest daily flow is likely
to be and how often it is likely to occur. For example, the 1-day average
flow of 200 cfs (129 mgd) for Big Coldwater Creek has an average re-
currence interval of about 7 years.
The seasonal distribution of runoff in Big Coldwater Creek basin
follows very closely the pattern of rainfall. The distribution of monthly
flows is given in figure 31. Heavy spring rains cause high runoff, thus
March and April have the highest average flows. High-intensity rain-
storms in July and August cause high peak flows. October is the month
of lowest flow.
Big Juniper Creek, which joins the Blackwater River 5 miles up-
stream from Big Coldwater Creek, drains 146 square miles, of which 134
square miles are in Florida. The streambeds in this basin are composed
of loosely packed sand and gravel, and the banks are steep and heavily
wooded.
The average flow from the Big Juniper Creek basin is estimated to
be 260 cfs, or 1.8 cfs per square mile, of which about 240 cfs comes from
the area within Florida. Flow was measured at the three sites within the
basin: Big Juniper Creek at State Highway 4, near Munson; Sweetwater
Creek at State Highway 4, near Munson; and Big Juniper Creek near
Harold. Runoff characteristics are similar at these three sites. Slightly
over one-half of the flow is base flow; the remaining is direct runoff
from overland flow.
The Blackwater River drains 580 square miles in Santa Rosa County
and 280 square miles in surrounding areas. The streams in this basin
bring 390 cfs into the county from surrounding areas, pick up 1,100 cfs
within the county, and discharge an average of 1,490 cfs into Blackwater
Bay.
The main stem of Blackwater River brings in most of the flow from
outside the county. The average flow at the Santa Rosa-Okaloosa county
line near Holt is estimated to be 440 cfs. The flow-duration curve given
in figure 16 is based on records collected at State Highway 4 near Baker
in Okaloosa County. The drainage area above this point is 205 square
miles. The daily flow has varied at this site from a low of 61 cfs to a
high of 10,300 cfs. The average flow is 320 cfs. The flood of December








FLORIDA GEOLOGICAL SURVEY


LOW-FLOW FREQUENCY
Example: For a IO-year recurrence
interval the I-day minimum flow
is 213cfs and the 12-month
minimum flow is 513cfs


1.5 2 3 4 6 8 10 20 30


RECURRENCE


INTERVAL, IN YEARS


Figure 30. Low-flow frequency curves for Big Coldwater Creek near Milton, 1938-61.


1200




1100


600


500


300


200


105 LI






REPORT OF INVESTIGATIONS No. 40


2000


1800


1600


1400


1200


1000


800


600


400


200


I JI F M A IM J J J A S N IDI
Figure 31. Graph of minimum, average, and maximum monthly discharge of
Big Coldwater Creek near Milton, 1938-61.







FLORIDA GEOLOGICAL SURVEY


4, 1953, reached a crest elevation of 81.3 feet above sea level at State
Highway 4 and a peak flow of 17,200 cfs.
The lower 6 miles of the Blackwater River channel varies in depth
from 10 feet to as much as 60 feet in holes. A depth-profile graph is
given in figure 32. At least 6 holes in the lower river are 35 to 60 feet
deep_ These deep holes trap salt water moving in from the Gulf and
could be a source of contamination of the surrounding ground water if
large capacity wells are located nearby and pumped heavily enough to
cause major drawdowns. The salt front during extreme high tides ex-
tends upstream about 6 miles from Blackwater Bay.









S0 2 Mie


I -I I
o c


Figure 32. Channel bottom profile of lower Blackwater River.






REPORT OF INVESTIGATIONS No. 40


MINERAL CONTENT
The surface waters of this basin are of exceptionally good quality,
with a mineral content ranging from 11 to 33 ppm, and the water is
slightly acid (pH 5.5 to 5.9). The low mineralization of this water can
be attributed to its flowing through an area of practically insoluble sands
and gravels.
On September 2, 1961, a chloride-profile run on the Blackwater
River (fig. 32) showed that salt water extended about 59 miles up-
stream. Apparently, the downstream flow of the river causes the salt
water to be funneled in to Wright Basin, this being a course of least
resistance. Unless there was a very high tide accompanied by a low
flow, the salt water would probably not extend much farther upstream
than Wright Basin.

YELLOW RIVER BASIN
OCCURRENCE OF WATER
Yellow River heads in southern Alabama, north of Andalusia and
Opp. The river flows in a southerly direction, entering Okaloosa County
north of Crestview. South of Crestview, it is joined by Shoal River, its
largest tributary. The river then turns southwestward, enters Santa
Rosa County, and flows southwestward into Blackwater Bay.
The Yellow River drains 1,365 square miles, of which only 115 are
in Santa Rosa County. Although only a small percentage of the basin is
in Santa Rosa County, the entire flow of the river is available to the
county. The average flow entering Blackwater Bay from the Yellow
River basin is about 2,500 cfs. This is the second largest flow in the two-
county area; the flow of Escambia River is the largest. Tides from the
Gulf of Mexico affect the flow in a large part of the 19-mile reach of
channel in Santa Rosa County. The main channel winds through a
heavily wooded, swampy flood plain about 2 miles wide. Several estu-
arine channels extend into the flood plain from Blackwater Bay. From
the Okaloosa County line to the mouth, there are several cutoff channels
that leave the main channel and re-enter farther downstream.

MINERAL CONTENT
The water of this basin is low in mineral content (23 to 32 ppm),
but has color ranging from 10 to 80 units. This color, owing to the river
flowing through a swampy area, makes the water objectionable for
many uses. Other than the color, the water is of very good quality.






FLORIDA GEOLOGICAL SURVEY


GROUND WATER
PRINCIPLES OF OCCURRENCE
Ground water is the subsurface water in the zone of saturation, the
zone in which all pore spaces are filled with water under pressure greater
than atmospheric. Potable ground water in Escambia and Santa Rosa
counties is derived from precipitation. Part of the precipitation reaches
the zone of saturation to become ground water. Ground water in Escam-
bia and Santa Rosa counties moves laterally under the influence of
gravity from places of recharge toward places of discharge, such as wells,
springs, and surface-water bodies.
Ground water in Escambia and Santa Rosa counties occurs undei
both nonartesian and artesian conditions. Where it is not confined, its
surface is free to rise and fall, and the water is under nonartesian con-
ditions. The upper water surface is called the water table. Where the
water is confined in a permeable bed that is overlain by a less permeable
bed, so that its water surface is not free to rise and fall, it is under arte-
sian conditions and the upper water surface in wells is called the arte-
sian pressure surface. The term "artesian" is applied to ground water that
is confined and under sufficient pressure to rise above the top of the
permeable bed that contains it, though not necessarily to or above the
land surface. The height to which water will rise in an artesian well is
called the artesian pressure head.
An aquifer is a formation, group of formations, or part of a formation
-in the zone of saturation-that is permeable enough to transmit usable
quantities of water. Places where aquifers are replenished are called re-
charge areas, and places where water is lost from aquifers are called
discharge areas.

HYDROLOGIC PROPERTIES OF THE AQUIFERS
Ground water in Escambia and Santa Rosa counties occurs in three
major aquifers: a shallow aquifer which is both artesian and nonartesian
(the sand-and-gravel aquifer), and two deep artesian aquifers (the
upper and lower limestones of the Floridan aquifer). In the southern
half of the area, the sand-and-gravel aquifer and the upper limestone of
the Floridan aquifer are separated by a thick section of relatively im-
permeable clay; but in the northern half the sand-and-gravel aquifer and
the upper limestone of the Floridan aquifer are in contact with one an-
other. The upper limestone of the Floridan aquifer is separated from
the lower limestone by a thick clay bed.







REPORT OF INVESTIGATIONS No. 40


SAND-AND-GRAVEL AQUIFER
The sand-and-gravel aquifer is composed of sand but has numerous
lenses and layers of clay and gravel. In the northeast corner of Santa
Rosa County, the aquifer extends from the first saturated beds (near
land surface) to a depth of about 350 feet. In the center of the area,
however, it extends to a depth of about 1,000 feet. This aquifer lies at
the surface throughout Escambia and Santa Rosa counties.
The shallow saturated permeable beds in the sand-and-gravel aquifer
contain ground water under nonartesian conditions, and the deep perme-
able beds contain ground water under artesian pressure. The artesian
water is confined by lenses of clay and sandy clay. Most of the water in
the sand-and-gravel aquifer is under artesian pressure.
The gradient of the water table in the shallow beds of the sand-and-
gravel aquifer generally indicates movement of ground water toward
the nearby streams. The seepage of this ground water supplies more than
half of the entire flow of the smaller streams in Escambia and Santa Rosa
counties. The water table is the highest under the broad, relatively level
lands that are at a higher elevation than surrounding lands. Examples of
places where the water table is high include the lands between Jay and
Milton, the lands between Pensacola and Cantonment, and the land
east of Milton.
The artesian pressure head of water in the lower permeable beds of
the sand-and-gravel aquifer does not conform to the topography of the
land as much as the water table. The artesian pressure head of water
from the lower beds indicates a general movement of water to the south.
The head of water in the northern part of both counties is usually more
than 100 feet above sea level and at some places is more than 150 feet
above sea level. In the central part of the counties, the artesian pressure
head is about 30 to 80 feet above sea level except near the larger rivers.
Upward leakage of ground water probably occurs which lowers the
pressure head of the ground water. The artesian pressure head of water
under the lands adjacent to the bays is usually less than 20 feet above
sea level and often less than 10 feet above sea level.

FLORIDAN AQUIFER
In Escambia and Santa Rosa counties, the Floridan aquifer is com-
posed of two sections of limestone separated by a thick clay bed. In the
northeast corner of Santa Rosa County, the upper surface of the Floridan
aquifer is only about 350 feet below the land surface; whereas in the
southwest corner of Escambia County the upper surface is more than






FLORIDA GEOLOGICAL SURVEY


1,800 feet below the land surface, owing to the southwestward dip of the
aquifer.
The Floridan aquifer is thickest, 1,300 feet, in north-central Santa
Rosa County and thinnest, 800 feet, at the Perdido River near Perdido
Bay. The thickness of the Bucatunna Clay Member has not been in-
cluded in the above figures.
The water in the Floridan aquifer is under high artesian pressure.
The artesian pressure head in wells drilled into the upper limestone of
the FIoridan aquifer in southeastern Santa Rosa County is about 50 to
70 feet above sea level (fig. 33). At low land-surface elevations, 50 to
several hundred gallons per minute by natural flow are obtained from
this aquifer; but the water is more mineralized than that from the sand-
and-gravel aquifer. Because suitable water of low mineral content usu-
ally is available near the surface, little use is made of the water from the
upper limestone in this area.

MOVEMENT OF WATER
Ground water in the sand-and-gravel aquifer moves from high to low
elevations. Ground-water levels usually correlate with land-surface ele-
vations. Thus, in the two counties, the general areas of ground-water
recharge can be delineated on topographic maps. Recharge is greatest
where the land is relatively flat. Water percolates downward to the wa-
ter table and then moves laterally toward the places of discharge.
The lower permeable beds in the sand-and-gravel aquifer are re-
charged by percolation of water from upper permeable beds through
and around beds of clay or sandy clay. The percolation results from
differences in the hydrostatic heads within the permeable beds.
The sand-and-gravel aquifer is recharged by local rainfall, which in-
filtrates to the water table. The aquifer is discharged by pumping;
evapotranspiration; and seepage into streams, swamps, bays, and the
Gulf of Mexico.
Data at Gulf Breeze were used to calculate the amount of recharge
received by the upper part of the sand-and-gravel aquifer for different
periods of time. Gulf Breeze was selected because the surface material
contains little clay, the water table is near the surface, and the direct
overland runoff is slight. In addition, no lateral movement of fresh
ground water to or from other areas is possible because Gulf Breeze is
on a peninsula. Thus, recharge from rainfall at Gulf Breeze would be as
great as anywhere in the area.
The highest percentage of recharge from rainfall, about 92 percent,







REPORT OF INVESTIGATIONS No. 40


occurred from a one-day rain on October 10, 1959. The 7.5-inch rainfall
on this day (at Pensacola Beach) caused a rise in the water table of
2.54 feet by the next day, equivalent to 7.0 inches of water computed by
using a coefficient of storage of 0.23. The loss by evapotranspiration in
one day was estimated as 8 percent. Later that month on the 28th, a
rain of 4.15 inches caused a rise in the water table of 0.92 foot. On the
assumption that the coefficient of storage remains a uniform 0.23, this
rise accounts for about 61 percent of the rain. These short-term recharge
values were obtained by comparing the amount of ground water taken
into storage if all the rain percolated to the water table to the amount of
water actually taken into storage.
The average annual amount of recharge from rain may be computed
by determining the amount of rain that falls on an area and computing
the amount of seepage from that area. The average water level near the
center of the peninsula at Gulf Breeze is 4.5 feet above sea level. This
gives a hydraulic gradient of about 9 feet per mile toward Pensacola Bay
and toward Santa Rosa Sound. Using this gradient and the rate of move-
ment of water through the sand, the average ground-water seepage into
either Pensacola Bay or Santa Rosa Sound would be about 305,000 gpd
per mile length of the peninsula. The total seepage into Pensacola Bay
and Santa Rosa Sound would be about 610,000 gpd per mile length of
the peninsula. The average rainfall at Pensacola from 1950 through 1961
was 61.6 inches. The average rain falling on a one-mile length of the
peninsula (which is about 0.95 square mile) was about 2,770,000 gpd.
The average daily seepage of fresh ground water represents the annual
amount of recharge from rainfall and is about 22 percent of the total
rain or 13.6 inches of rain. The figures do not take into account the loss:
by pumpage of ground water and the loss by evapotranspiration after
the water reaches the water table. The amount of water removed by
these processes would increase the recharge to possibly 25 to 28 percent
or about 15 to 17 inches of rain.
A graph of monthly rainfall at Pensacola and graphs of the water
levels in an artesian well and in two nonartesian wells, drilled into the-
sand-and-gravel aquifer, are illustrated by figure 33. Wells 054-726-1
and 054-726-2 are at Oak Grove in northern Escambia County, and are-
about 6 feet apart. Well 055-726-1 is 0.6 mile north of these two wells.
Relatively permeable and impermeable beds and changes in water levels-
caused by rainfall are shown in figure 33.
Well 054-726-1 was drilled to a depth of 206 feet and is screened from
201 to 206 feet in a permeable sand bed. Although the top of the bed is
190 feet below the surface, the water in the well rose to within 83 to 90








60 FLORIDA GEOLOGICAL SURVEY


feet of the surface. The artesian pressure head ranged from 170 to 177

feet above sea level during the period of record. The artesian pressure

head rose about 3 feet from May 1959 to July 1960, then declined about
2 feet until February 1961. High rainfall periods in 1961 and 1962 caused

the head to rise more than 5 feet until April 1962. From April until


_7













Sketch shownq location of
ells 054726-1,2 and
055-726-f.







Screen On
054ell 054-726-2







EXPLANATION

Relatvely permeoable

Relatively impermeable

Sand

Cl y


Screen n
well 054-726-2
enit 054-726-I


Graphic
log



25


U 50





75





CCC
1-5









200 1


1959 1960 1961 1962

Figure :33. Water levels in an artesian well and two nonartesian wells drilled into the
sand-and-gravel aquifer in northern Escambia County, and graph of monthly rainfall
at Pensacola.



September 1962, the artesian pressure head declined about 2 feet be-

cause of below normal rainfall.
Well 054-726-2 was drilled to a depth of 107 feet and is screened

from 102-107 feet in a permeable sand bed. The water in this bed is not

under artesian pressure, and its upper surface is free to rise and fall. The
water level ranged from 184 to 194 feet above sea level during the period

of record. The water level rose several feet every spring or summer. Be-


'186 1-- 76

.4185 75 ...r

w841 174

< 173
Iell 054-726-1 (Artesian)
- /Oeplh 206 feel

171



169

S1Well 055-726-l(Nonorlesion)
6Depth 49 feet
167 .. .
20
Totoli797inches Totol-677inches Totol -79 inches I Tol'427 inches
_j tO

0







REPORT OF INVESTIGATIONS No. 40


cause the land around Oak Grove is cultivated, tilling the soil may in-
crease the amount of recharge from rainfall.
Well 055-726-1 was drilled to a depth of 80 feet and screened from
44 to 49 feet in a permeable sand bed (fig. 34). This sand bed is be-
lieved to be a continuation of the bed tapped by well 054-726-2. The


IpOO 0


1,000


I0
2POO


3,000


4,00O


DISTANCE, IN FEET FROM PINE BARREN CREEK
Figure 34. Cross section showing geology and hydrology in northern Escambia
County.

water in this bed is not under artesian pressure. The water level ranged
from 167 to 170 feet above sea level during the period of record. The
water level fluctuation in well 055-726-1 was similar to the fluctuation in
well 054-726-2, but much less. Well 054-726-2 is near the center of a
recharge area at Oak Grove and the water level in this well changed
about 10 feet. Well 055-726-1 is about 600 feet south of a discharge area,
Pine Barren Creek, and the water level in this well changed only about
3 feet. Water-level changes are usually much greater near areas of re-
charge than those near areas of discharge.


Note Well locations shown on figure 33
Cross section located 12miles west- southwest of
Century and along State Rood 99






FLORIDA GEOLOGICAL SURVEY


Figure 34 shows some geologic and hydrologic conditions in the Oak
Grove area. The beds of clay and sandy clay have been classed as rela-
tively impermeable beds. The beds of sand, sand and gravel, and gravel
have been classed as relatively permeable beds. In the vicinity of wells
054-726-1 and 2, ground water is recharged from local rainfall. Most of
this recharge moves northward and seeps into Pine Barren Creek. Some
of the recharge percolates downward to the lower permeable zone.
Ground water in this lower permeable zone may also seep into Pine
Barren Creek or move southward and discharge into other streams.
The water level in well 054-726-2 is generally from 14 to 18 feet
higher than the level in well 054-726-1. Thus, water in the upper perme-
able sands has the head potential to recharge the lower permeable sands.
The water level in the upper sands shows more response to high rainfall
than that in the lower sands.
The Floridan aquifer is recharged by rain in areas where the lime-
stones outcrop in Conecuh, Escambia, and Monroe counties, Alabama,
10 to 35 miles north of the area. The upper limestone of the Floridan
aquifer probably is recharged also by percolation from the sand-and-
gravel aquifer in the northern half of the area. The aquifer is discharged
by seepage into the Gulf, upward and downward leakage, and pumping.

GROUND-WATER VELOCITIES
The rate of ground-water flow depends upon the slope of the water
surface, the permeability of the aquifer, and the temperature of the
water. A knowledge of the rate of ground-water flow is useful to deter-
mine how fast and how far contaminated ground water will move, to
predict future areas of salt-water encroachment, and to evaluate the
effectiveness of clay beds as aquicludes.
Using the earliest water-level data available, Jacob and Cooper
(1940, p. 50-51) computed the average ground-water velocity in the
sands near Pensacola Bay to be 0.37 foot per day, or 135 feet per year.
The figure given represents the velocity under natural, undisturbed
conditions. In the vicinity of discharging wells, the velocities would, of
course, be higher.
The average velocity of ground water moving through an aquifer
may be computed by the following formula:

Tg
V=-
7.48 mp
Where: V is the velocity in feet per day; T is the coefficient of trans-
missibility in gpd (gallons per day) per foot; g is the gradient of the







REPORT OF INVESTIGATIONS No. 40


water table in feet per mile; m is the thickness of the aquifer in feet; and
p is the porosity of the aquifer in percent.
Data from Gulf Breeze was used to compute the highest, average,
and lowest velocities of the water in the upper part of the sand-and-
gravel aquifer. In 1959, the water level at Gulf Breeze was 9.8 feet above
sea level, the highest level during the last 13 years. This level would
give an average gradient of 23 feet per mile (or 0.0044) toward Pensa-
cola Bay. The coefficient of transmissibility averages about 34,000 gpd
per foot and the aquifer is 80 feet thick. The porosity is assumed to be
about 30 percent. These figures give the highest velocity of ground water
in Gulf Breeze from the center of the peninsula toward Pensacola Bay of:
(34,000) (0.0044)
V (34,) (0.0044) = 0.83 foot per day,
(7.48)(80)(0.30)
or about 300 feet per year.
An inspection of the hydrograph at Gulf Breeze (fig. 38) gives an
average water level of 4.5 feet above sea level. Using this level, the av-
erage velocity of ground water is computed to be 0.38 foot per day or
about 140 feet per year. The lowest water level, 2.8 feet above sea level
(except when the water level was lowered by nearby pumping), oc-
curred in 1951. Using these data, the lowest velocity of ground water is
computed to be 0.24 foot per day or about 90 feet per year.

AREAS OF ARTESIAN FLOW
Water will flow from artesian wells when the artesian pressure head
is higher than the land surface. The water from rainfall percolates into
the ground in the higher, relatively level land and moves downward and
laterally toward places of discharge. Some of this water is confined by
impermeable beds below which the water is under artesian pressure.
The areas of flow of water from the sand-and-gravel aquifer in the
two counties are usually low lands along streams. One area of artesian
flow is at Molino, near the Escambia River, where the artesian pressure
head is more than 20 feet above the land surface in places. At Pine
Barren, the artesian pressure head is as much as 30 feet above the land
surface.
Water from the upper limestone of the Floridan aquifer is under
sufficient artesian pressure to rise to more than 50 feet above sea level
in the southeastern part of the area. Thus, the areas of flow from wells
that tap the Floridan aquifer are generally at elevations less than 50 feet
above sea level. Examples of areas of artesian flow of water from the
Floridan aquifer are at Gulf Breeze Peninsula, Holley, Navarre, Navarre






FLORIDA GEOLOGICAL SURVEY


Beach, Pensacola Beach, and the western two-thirds of Santa Rosa
Island.
Ihe artesian pressure head of water from the Floridan aquifer ranges
from about 140 feet above sea level in northern Santa Rosa County (well
059-658-1) to about 55 feet above sea level in southern Santa Rosa
County (well 022-652-1). Therefore, the artesian pressure head in the
Floridan aquifer would be greater than the water table in the sand-and-
gravel aquifer at most of the low to moderate land elevations in the two
counties. The water in the Floridan aquifer would have a potential up-
ward flow. The water level in the sand-and-gravel aquifer would stand
above the artesian pressure head of the Floridan aquifer in the higher
land elevations of the area and would have a potential downward flow.

FLUCTUATION OF THE WATER LEVEL
Water-level records show that the water surface is not stationary but
fluctuates almost continuously. Water-level fluctuations result from vari-
ations in recharge and discharge. Discharge is from evaporation and
transpiration, seepage, and pumping. Recharge is from rainfall and
seepage from other aquifers. Long-term periodic measurements of water
levels are used to determine significant changes in the water in storage,
to correlate water levels and rainfall, and to show the influence of pump-
ing on the water level. Long-term records are needed to distinguish
between short-term fluctuations and progressive trends.
Over most of the area, changes in the water level correlate in general
with rainfall. In the heavily pumped areas, water levels reflect both the
influence of the pumping and the rainfall.
Figure 35 compares changes in the artesian pressure head in a well
drilled into the Floridan aquifer with changes of the water level in a
well drilled into the sand-and-gravel aquifer. Well 037-645-1 is at Aux-
iliary Field 6, located 18 miles east of Milton, in Okaloosa County. This
well is 690 feet deep and obtains water from the upper limestone of the
Floridan aquifer from 527 to 690 feet below land surface. Well 032-648-1,
15 miles southeast of Milton, is 197 feet deep and obtains water from the
sand-and gravel aquifer from about 140 to 197 feet below land surface.
Well 037-645-1 is a representative well for this area. It taps the upper
limestone of the Floridan aquifer and has a long-term record. The hy-
drograph is included to show the relation between artesian pressure
changes and the use of water, to illustrate the fluctuations in artesian
pressure in the upper limestone of the Floridan aquifer, and to compare
these fluctuations with those in the sand-and-gravel aquifer.







REPORT OF INVESTIGATIONS No. 40


The hydrograph for the shallow well shows the water-level changes
during the last 15 years in an area where there is not much withdrawal
of ground water. When compared to rainfall records, the graph shows a
general correlation with rainfall and reflects a very wet period from
1944-49, a relatively dry period from 1950-55, a wet period from

90 I I I i- i- i i I- I- -I -
Well 037-645-1, 18 miles east of
Milton (in the upper limestone of the
Floridon aquifer') Depth 690 feet.



85



,.-,

80 -7
75 ____-






0 5 10 15 miles

= Well 032-648-1, 15 miles southeast of
S55 Milton (in the sand and grovel
Soaquifer) Depth 197 feet.




50 4 A .






Figure 35. Hydrographs of wells 037-645-1 and 032-648-1.

1956-61, and another dry year in 1962. The effect of 90.41 inches of
rainfall in 1953, the highest recorded in 83 years at Pensacola, is shown
by the rise in water levels during 1953 and the first part of 1954. How-
ever, this trend in the water level was reversed by the effect of the low-
est rainfall on record, 28.68 inches, in 1954. Declining water levels dur-
ing 1954 and the first half of 1955 reflect this low rainfall. The maximum






FLORIDA GEOLOGICAL SURVEY


change observed during the period of record was 13 feet. The water
level was highest, 56 feet above sea level, in 1949, and lowest, 43 feet
above sea level in 1955.
The hydrograph for well 037-645-1, which penetrates the upper lime-
stone of the Floridan aquifer, shows very different fluctuations. The
hydrograph shows a progressive decline in the artesian pressure head of
21 feet during the period of record. Artesian pressure was highest, 88
feet above sea level, in 1948 and lowest, 67 feet above sea level, in 1962.
The artesian pressure head stood above the water level in the sand-and-
gravel aquifer during the entire period of record.
The hydrograph for well 037-645-1 shows the decline of the artesian
pressure head that has occurred in the upper limestone of the Floridan
aquifer, in the Fort Walton Beach area. Barraclough and Marsh (1962)
found this decline to be greatest at Fort Walton Beach, about 17 miles
to the southeast, where one well had a decline of about 56 feet between
1948 and 1960, and a net decline of 125 feet between 1936 and 1962.
The amount of decline increases toward Fort Walton Beach and results
from use of water by Fort Walton Beach, Eglin Air Force Base, and
others. In addition, the decline relates to thinning of the upper limestone
northward from about 400 to about 40 to 60 feet thick. This thinning has
a restricting effect on the amount of water moving through the aquifer.
Barraclough and Marsh (1962) noted the large amount of clay in the
aquifer, both in beds and clay-filled voids, and suggested that the clay
within the aquifer reduces both the permeability and effective porosity
of the aquifer, resulting in the large drawdowns.
The artesian pressure head in well 037-645-1 has declined at an av-
erage rate of 1.4 feet per year. Wells that tap the upper limestone of the
Floridan aquifer in southeastern Santa Rosa County around Navarre
probably have had a similar rate of decline which may continue. Farther
away from the Fort Walton Beach, the artesian pressure heads have de-
clined at a slower rate.
Figure 36 contrasts changes of the water level in an area affected
slightly by pumping, as shown by well 031-716-1 at Ensley, with changes
of the water level in areas of heavy pumping, as shown by well 036-719-1
at Cantonment and well 036-716-1, 3 miles east of Cantonment. All three
wells are in the sand-and-gravel aquifer. From 1940 to 1962, the water
level at Ensley varied a maximum of 26 feet; the water-level high of 75
feet above sea level was recorded in 1948, and the water-level low of
49 feet was recorded in 1956. Well 031-716-1 is 239 feet deep. The rise
and fall of the water table in this area, as shown by the graph, closely
follows variations in rainfall. In general, whenever the annual rainfall









REPORT OF INVESTIGATIONS No. 40


50


60--




50 -





40
036-719-I,
at Cantonment
Depth 152 feet

30


I I I I


Conlonment SANTA ROSA
CO.
-".036-7t6-,
036-719-1
N

Ensley
031-716-1
SCAMBIA C O.
Pensacolo


0 2 4 6 8 10 miles




-NORMAL--
100-
Un
1: 80-

z


'0

< 20
1| 1////,"Y


EXPLANATION


Continuous record

Periodic record


20





10

036-716-1, 3 miles
W east of Cantonment
Depth 352 feet
i -- l I l- I i -- -- -


Figure 36. Hydrographs of wells 031-716-1, 036-719-1, and 036-716-1 and graph of
yearly rainfall at Pensacola.


-o
w
w





'0
w





2
Ui


w


. ,






FLORIDA GEOLOGICAL SURVEY


was less than 60 inches, the water level declined; and whenever the
annual rainfall exceeded 60 inches, the water level rose.
The water level in well 031-716-1 was about 10 feet lower in 1959-60
than in 1948-49 (fig. 36). The graph of well 032-648-1 (fig. 35) shows
a high water level in 1948-49 and a similar high water level in 1959-60.
Industrial pumping at St. Regis, 7 miles north-northeast of well 031-716-1
is believed to be the principal factor limiting the rise of the water level
in 1959-60.
Figure 36 shows the water level in- well 036-719-1 (152 feet deep) at
Cantonment. This hydrograph shows the decline usually associated with
continued, concentrated pumping in an area. During 23 years of record,
the water level fluctuated 42 feet. The highest water level was 65 feet
above sea level in 1941 and the lowest was 23 feet above sea level in
1957. The slight rise and then gentle decline of water levels for 1946-49
shows the effect of abnormally high rainfall.
The sharp decline of the water level in well 036-719-1 stopped in
1956. Late in 1958 the water level started to recover. This recovery was
the result of the following: (1) several nearby wells were taken out of
service; (2) rainfall was above normal in 1956 and 1958-61; (3) a re-
charge experiment was conducted by St. Regis Paper Company; and
(4) the use of cooling towers that began in 1961 lowered the pumping
rate. During this recharge experiment cooling water was pumped into a
nearby well at a rate of a million gallons per day for a year. The recharge
well is located 2,170 feet from well 036-719-1 and the calculated time-
distance-recovery curves indicate that this amount of recharge would
cause the nonpumping water level in well 036-719-1 to rise from 1 to
2 feet.
The hydrograph of well 036-716-1, about 3 miles east of Cantonment
and about 1 mile west-northwest of the Chemstrand Corporation plant,
is shown in figure 34. This well is 352 feet deep and is screened from
260 to 270 feet and from 340 to 350 feet below the land surface. The
water level is affected by pumping at two nearby industrial plants, the
St. Regis Paper Company and the Chemstrand Corporation. The graph
shows a maximum change of 16 feet during the 11 years of record, with
the highest water level being 24 feet above sea level in 1951 and the
lowest water level being 8 feet above sea level in 1959. The water level
declined rapidly from 1951 to 1957 owing to pumping and below-normal
rainfall. The water level was nearly stable during 1958 and recovered
about 3 feet from 1959 to 1962 owing to above-normal rainfall, infiltra-
tion of water from the Escambia River into the well field of the Chem-
strand Corporation, and reduced pumpage at St. Regis and Chemstrand.








REPORT OF INVESTIGATIONS No. 40


Figure 37 shows the water levels southwest of Pensacola, as recorded
in three wells. Two of the wells, 024-715-1 and 024-715-2, are near the
Newport Industries plant at Pensacola. Well 023-716-2 is in Warrington,
about 2 miles southwest of the plant. Well 024-715-1 is 142 feet deep and
is at Pensacola, 450 feet from Bayou Chico. The range of water-level
fluctuations in this well was 18.6 feet during the 23 years of record. The
water level was highest, 7.8 feet above sea level, in 1949 and lowest,
10.8 feet below sea level, in 1955. The water level in well 024-715-1 is


6 -- I i i I I i i I I
024-715-2,( beside024-715-1)
Depth 17.5 feet.



o "


Figure 37. Hydrographs of wells 024-715-1, 024-715-2, and 023-716-2.


I I I I I






FLORIDA GEOLOGICAL SURVEY


influenced by heavy pumping at Newport Industries and by changes in
rainfall. The water level was lowered by pumping before water-level
measurements were started in 1940.
Ground-water pumping at Newport Industries started in 1918 at an
average rate of 2 mgd and increased to an average rate of 9 mgd in
1939. Cooling towers were installed in 1941, 1948, 1954, and 1962. Re-use
of some of the water reduced the average pumping rate to 3.6 mgd in
1962.
The hydrograph of well 024-715-1 shows that the water level has
been lowered by heavy pumping by Newport Industries and has been
below sea level most of the time since the summer of 1952. As salt water
in Bayou Chico is only 450 feet from the well, the lowered fresh-water
levels could cause salty water from the bayou to percolate into the aqui-
fer in this area and destroy its usefulness.
Well 024-715-2, which was drilled beside well 024-715-1, is 17.5 feet
deep. The water level in well 024-715-2 had a range of only 4.4 feet dur-
ing the 23-year period of record. The water level rose to 5.2 feet above
sea level in 1956 and declined to 0.8 feet above sea level in 1951, 1955,
1957, 1958, and 1962.
The water level in shallow well 024-715-2 has been above the water
level in deep well 024-715-1 for most of the 23 years of record. The
greater head of water in the upper permeable beds permits some re-
charge to the lower permeable beds. However, some of the water from
the shallow zone moves laterally into Bayou Chico.
The hydrograph of well 023-716-2 (247 feet deep) at Warrington
shows that the highest water level was 6 feet above sea level in 1940,
and the lowest was 4 feet below sea level in 1952. The graph shows a
slight decline of the water level during the 23-year period, 1940-62,
owing to increased use of ground water in the Warrington area. During
the summers of 1943-45, 1950-58, and 1960-62, 15 of the 23 years of rec-
ord, the water level declined below sea level. The lowering of the water
during the summer is brought about by an increase in the use of ground
water.
The water level in well 021-709-8, half a mile east of the Gulf Breeze
post office, is shown in figure 38. This well was drilled to a depth of 41
feet and the lower 10 feet of the well was screened. During the 13-year
period of record, the water level fluctuated 8.6 feet. The highest water
level was 9.8 feet above sea level in 1959, and the lowest was 1.2 feet
above sea level in 1955.
Fresh ground water on Gulf Breeze Peninsula is derived entirely from
local rainfall. Some of the rain water percolates quickly through the










REPORT OF INVESTIGATIONS No. 40


I10 I I i i
> Well 021-709-8










1950 1955 1959 1962 Si

J Waler level affected Beezd
I- by nearby pumping peninsula
Z PERIODS OF RAINFALL
1. DRY < WET- DRY -
LL


W
-J
Ir
I
1-


ti


zj
I-I

wi


-I


Well 021-709-8


6

4
JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC
1959
16

14
RAINFALL AT PENSACOLA __ RAIFALL TOTAL
12 1959 TOTAL= 79.67 INCHES SEPT OCT
2 /29.6 INCHES /
io


















Well 021-709-B8
______ -__ _y_///,_ /.__ ,, __" __/__
6













1954 TOTAL 7 728.68 INHES
JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC
1959


-<

" Well 021-709-8






JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC
1954
- RAINFALL AT PENSACOLA _
l' 1954 TOTAL =28.68 INCHES




<4




JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC


1954

Figure 38. Hydrograph of well 021-709-8 and graph of the rainfall at Pensacola.






FLORIDA GEOLOGICAL SURVEY


few feet of sand to the water table. Ground water then moves laterally
and discharges into Pensacola Bay or Santa Rosa Sound. The water in
the upper part of the sand-and-gravel aquifer is under nonartesian con-
ditions, and the water level rises rapidly after intense rainfall and de-
clines slowly during prolonged periods without rain. The hydrograph of
well 021-709-8 shows the response of the water level to rainfall. Pump-
ing from nearby wells also had an influence on the water level in this
well. Wells owned by the Santa Rosa Island Authority were pumped at
rates of about 60,000 gpd during the winter and about 120,000 gpd dur-
ing the summer from 1951 to 1956. After 1956, when the pumping from
these wells ceased and rainfall was above average, the water level rose
gradually to a record high in 1959. From the high water level in late
1959 to mid 1962, the water level declined about 6 feet.
The hydrograph of water levels in well 021-709-8 and the monthly
rainfall at Pensacola for 1959 shows the rapid rise of the water level that
resulted from intense rainfall. The water level changed only slightly
until heavy rains in September caused a rise of 2.5 feet. Additional heavy
rains in October caused rises totaling about 4 feet. A total of almost 30
inches of rain fell in Pensacola in September and October 1959. These
rises brought the water table near or above the land surface in some areas
around Gulf Breeze, causing some damage and considerable incon-
venience.
The 1954 hydrograph in figure 38 illustrates a decline of the water
level during a year of low rainfall. In 1954, Pensacola had the lowest
rainfall of record, 28.68 inches. The water level at Gulf Breeze declined
6.2 feet during this year. The water level declined 5.7 feet from January
to September and remained less than 2 feet above sea level until the
end of the year. The ground-water table received very little recharge
from rainfall in 1954. Most of the rain was lost through evapotranspira-
ion.

TEMPERATURE OF GROUND WATER
The temperature of the earth's crust increases with depth at the rate
of about 10F. for each 50 to 100 feet. The temperature of ground water
generally increases with depth at approximately the same rate.
Ground-water temperatures in Escambia and Santa Rosa counties
from the sand-and-gravel aquifer 50 to 250 feet deep usually range from
66' to 730F. These temperatures reflect the average annual air tempera-
ture (680) at Pensacola and the geothermal gradient.
The temperature of water from the upper limestone of the Floridan






REPORT OF INVESTIGATIONS No. 40


aquifer in southern Escambia and Santa Rosa counties ranges from 840
to 920F. The wells that tap this aquifer are from 900 to 1,500 feet deep.
The temperature of ground water in this area usually increases about
1F. for each 52 to 85 feet of depth. For example, the geothermal gra-
dient 9 miles southwest of Pensacola, as shown by measurements made
in an oil test hole, is about l0. for each 81 feet of depth down to 12,500
feet. The temperature at the bottom of the hole was 2220F.

SPECIFIC CAPACITY
The specific capacity is used to indicate the amount of water, in
gallons per minute, that can be obtained from a well for each foot of
drawdown of water level in the well. The specific capacity is obtained
by dividing the yield of the well in gallons per minute by the difference
of the static water level and the pumping water level in feet. Factors
that affect the yield of wells include: (1) the diameter of the well;
(2) depth of aquifer penetrated; (3) transmissibility of the aquifer;
(4) efficiency of the pump; (5) amount of well development; (6)
amount and size of well screen (if any); and (7) the friction loss
within the well.
An example of the specific capacity of wells drilled into the sand-
and-gravel aquifer can be shown by data from 8 wells at the Chemstrand
Corporation nylon plant. The wells are constructed similarly with 24-
inch casing at the surface, 16-inch casing in the middle, and 12-inch
screen at the bottom. The amount of well screen is usually 110 feet and
the wells are pumped at 1,500 gpm for 24 hours. The specific capacity
ranged from 39.5 to 76.8 gpm per foot of drawdown and the average
specific capacity was 53 gpm per foot of drawdown.
Little information is known about the specific capacity of wells from
the Floridan aquifer in the area of study. However, large-capacity wells,.
10 to 16 inches in diameter, drilled into the Floridan aquifer in southern
Okaloosa and Walton counties had a specific capacity ranging from 10 to
100 gpm per foot of drawdown. The average specific capacity was 88
gpm per foot of drawdown. Similar values could be expected from wells
drilled into the Floridan aquifer in Escambia and Santa Rosa counties.

QUANTITATIVE STUDIES
The withdrawal of water from an aquifer creates a depression in the
water table or artesian pressure surface around the point of withdrawal.
This depression generally has the form of a cone with its apex down
and is referred to as the cone of depression. The amount by which the






FLORIDA GEOLOGICAL SURVEY


water surface is lowered at any point within this cone is known as the
drawdown. The size, shape, and rate of growth of the cone of depression
depend on several factors: (1) the rate of pumping; (2) the duration of
pumping; (3) the water-transmitting and storage capacities of the aqui-
fer; (4) the increase in recharge resulting from the lowering of the
water surface; (5) the decrease in natural discharge from the aquifer
due to the lowering of that surface; and (6) the hydrologic boundaries
of the aquifer.
A measure of the capacity of an aquifer to transmit water is the co-
efficient of transmissibility. This is the quantity of water in gpd (gallons
per day), that will move through a vertical section of the aquifer 1 foot
wide and extending the full saturated height of the aquifer, under a unit
hydraulic gradient, at the prevailing temperature of the water.
The coefficient of storage is a measure of the capacity of an aquifer to
store water. It is defined as the volume of water released from or taken
into storage per unit surface area of the aquifer per unit change in the
component of head normal to that surface.
The amount of water that may be stored in a rock or soil is limited by
the porosity of the material. The amount of water that a saturated rock
will yield when allowed to drain is somewhat less than the porosity
because some of the stored water will be held by capillarity.
The amount of water stored by an aquifer also depends on whether
the aquifer is artesian or nonartesian, for all aquifers serve as both con-
duits and reservoirs. An artesian aquifer functions primarily as a conduit,
transmitting water from places of recharge to places of discharge; how-
ever, it is capable of storing water by expansion, or releasing water by
compression. An artesian aquifer also stores water in the unconfined por-
tion of the aquifer. A nonartesian aquifer functions primarily as a reser-
voir and can store a much larger quantity of water for a given rise
in the water level than can be stored in an artesian aquifer.
The coefficient of transmissibility and coefficient of storage are gen-
erallv determined by means of an aquifer test on wells. Although only a
few aquifer tests have been made during the current investigation, many
detailed tests have been made in parts of the area. The coefficients deter-
mined by these tests are still applicable to the test areas and may be
used for hydrologically similar areas.
In the spring of 1940, Jacob and Cooper (1940, p. 33-49) made sev-
eral aquifer tests on wells owned by the City of Pensacola, the U.S. Navy
(at Corry Field), and Newport Industries. These wells were drilled
about 240 feet into the sand-and-gravel aquifer, and the lower half was
screened. The average coefficient of transmissibility, T, for 120 feet of






REPORT OF INVESTIGATIONS No. 40


aquifer, as determined by the tests is 75,000 gpd per foot. The coefficient
ranged from 58,800 to 94,000 gpd per foot. This coefficient may be used
to calculate the effects of pumping on the water level near Pensacola.
The average coefficient of storage is 0.00055. This relatively low average
coefficient of storage indicates that an effective confining layer overlies
the sands from which the water is withdrawn. However, this confining
layer does not extend over a large area.
The aquifer tests show that artesian conditions existed during the few
clays of the tests and perhaps artesian conditions would exist for as long
as a few weeks after continuous pumping started. Later, local recharge
by leakage from other parts of the sand-and-gravel aquifer would prob-
ably occur at the edges of and through the confining layers. This local
recharge would lessen the drawdown. Because of the effect of this re-
charge, it has been found by trial and error that reasonably accurate
drawdowns can be predicted using a storage coefficient of 0.15 in this
area. This coefficient of storage would give more reasonable time-distance-
drawdown figures than those calculated by using the average coefficient
obtained from the relatively short pumping tests. Jacob and Cooper
(1940, p. 48) calculated the "apparent coefficient of storage" to be 0.32 in
the upper sands in the Pensacola area. This calculated coefficient of
storage takes into consideration the effects of local recharge.
In the fall of 1950, Heath and Clark (1951, p. 31-34) made an aquifer
test on the Gulf Breeze Peninsula in Santa Rosa County. The test area was
about half a mile east of the Gulf Breeze post office. The wells pene-
trated the upper part of the sand-and-gravel aquifer and the coefficients
that were determined apply to the upper 75 feet of the aquifer. This
part of the aquifer was found to have a coefficient of transmissibility of
84,000 gpd per foot and a coefficient of storage of 0.23. This relatively
high storage coefficient indicates nonartesian conditions. Several curves
relating pumping rates and well spacing to the resultant drawdowns are
given in the report.
Several aquifer tests have been made during 1951-55 on some of the
Chemstrand Corporation's wells, about 13 miles north of Pensacola. Each
supply well is equipped with 110 feet of well screen, usually made up in
two sections. The screens are set in the most permeable zones in the sand-
and-gravel aquifer, between 170 and 380 feet below the sand surface.
The average value of the coefficients of transmissibility and storage de-
termined from these tests were about 150,000 gpd per foot and about
0.001, respectively.
The coefficients of transmissibility and storage may differ consid-
erably from place to place; therefore, drawdowns at one place cannot







FLORIDA GEOLOGICAL SURVEY


be predicted on the basis of data collected elsewhere. Figure 39 illus-
trates how water levels are affected in the vicinity of a pumped well
near the Chemstrand plant. This figure shows theoretical drawdowns in
the vicinity of a well pumped at the rate of 700 gpm (about 1 mgd)
from an aquifer having a transmissibility coefficient of 150,000 gpd per
foot and a storage coefficient of 0.15. As the drawdowns outside the
pumped well vary directly with discharge, drawdowns for greater or


DISTANCE. IN FEET. FROM PUMPED WELL
100 1,000

------ I 7


S.. .. .... Computed on the bosis of:
ST rSO150,000 gpd/ft
;0 '5 015
Q 700 gpm i
Note Compulolaons based on pumpig from storage from on
1Logqufer of lorge orel extent

Figure 39. Graph showing theoretical drawdowns in the vicinity of a well.

lesser rates of discharge may be computed from these curves. For ex-
ample. as shown in figure 39, under the assumed conditions, the draw-
down 100 feet from a well discharging at 700 gpm would be 4.3 feet after
100 days of pumping. If the well had discharged 2,100 gpm for the same
length of time, the drawdown at the same distance would have been
three times as much, or 12.9 feet.

MINERAL CONTENT
THE SAND-AND-GRAVEL AQUIFER
The sand-and-gravel aquifer is the major source of ground water used
in Escambia and Santa Rosa counties. Differences in the composition of
the aquifer affect the chemical quality of the water. In some areas clay







REPORT OF INVESTIGATIONS No. 40


lenses likely cause ionic exchange, resulting in water of altered mineral
content, and the solution of fossil shells in some formations probably con-
tribute to the mineralization. The general area of recharge is outlined in
figure 40 by the low sums of the mineral constituents in parts per mil-
lion. The low mineral content in the recharge area may be due to the
short time of contact between the water and the sand, gravel, and clay.
As the water moves into the aquifer and down and away from the re-
charge area, this mineralization increases. Inset "A" in figure 40 shows


Figure 40. Map of Escambia and Santa Rosa counties showing mineral content of
water from the sand-and-gravel aquifer.








FLORIDA GEOLOGICAL SURVEY


mineral content of water from deep wells in the sand-and-gravel aquifer.
Except for a few areas, the sum of mineral constituents in the water
of this aquifer is very low (12-36 ppm) throughout the two counties.
Figure 41 shows the type of ground water based on the major constitu-
ents in solution, regardless of total concentration. All elements are di-
vided roughly into two groups, metal and non-metals. In solution the
metals calcium, magnesium, sodium, and potassium are positively
charged cationss) and the non-metals carbonate, sulfate, chloride, fluo-


Figure 41. Map showing types of water from wells in the sand-and-gravel aquifer.







REPORT OF INVESTIGATIONS No. 40


ride, and nitrate are negatively charged anionss). Chloride-type water is
indicated by chloride as the major anion and is generally accompanied
by a predominant sodium cation. Carbonate-type water is based on car-
bonate as the major anion and calcium, magnesium, and sodium, either
singularly or in various combinations, being the major cations.
Intermediate-type water is characterized by carbonate and chloride
being almost equal and usually shows no predominance in the cations.
The chemical quality of the water from two wells located at Fort
Pickens State Park on the west end of Santa Rosa Island is distinctive.
They are the only two wells on Santa Rosa Island producing any quantity
of fresh water from the sand-and-gravel aquifer. The analysis of the wa-
ter from these two wells suggests the presence of a slight amount of
sea water. Sodium and chloride are among major ions present and the
magnesium exceeds the calcium, which is indicative of sea water. The
water has a pH slightly above neutral and a carbonate of 95 ppm, high
for this area. These two factors could be attributed to the action of the
usually acid water on fossil shells. This water is thought to cross under
the bay from the Pensacola area, separated from the salt water in Pensa-
cola Bay by an impermeable clay bed. The long exposure to clay could
account for the presence of high silica (20 ppm).
On Fair Point Peninsula, Heath and Clark (1951) found two aquifers
in the sand-and-gravel aquifer. The upper aquifer contains the more acid
water (pH 5.2 to 5.9) which has sodium and chloride for the major con-
stituents and is low in total mineralization. Water from the lower, more
fossiliferous aquifer contains carbonate as the major constituent and has a
pH of 7.2. A shallow well at Gulf Beach and a deeper well at Navarre
show chemical characteristics similar to the deep well at Fair Point,
whereas water from a shallow well at Santa Rosa Shores resembles the
water from wells in the upper aquifer at Fair Point. Water from the
sand-and-gravel aquifer in the southeastern part of Santa Rosa County
away from the coast has a very low mineral content and shows no pre-
dominant chemical constituents.
In the section of Pensacola bordering closely on the bays, the water
from this aquifer is generally very low in mineral content but shows a
predominance of sodium and chloride ions. This slight salt-water en-
croachment could be due to pumping in the area. Near Bayou Chico, an
area of heavy pumping in close proximity to salt water, about 12 wells
have been abandoned due to salt-water encroachment. This encroach-
ment has been reduced by decreasing pumping near the salt water.
The large Chemstrand plant on the Escambia River just north of
Pensacola uses both river water and ground water from the sand-and-






FLORIDA GEOLOGICAL SURVEY


gravel aquifer. During periods of low flow and high tides, salt water
extends up the river past the plant. At these times, heavy pumping can
cause salt water to enter the aquifer. This happened in Chemstrand well
035-714-4 where the chloride rose to 1,100 ppm before they abandoned
the well. Due to the loss of this well, pumping was decreased in several
other wells to prevent a recurrence of salt-water encroachment. The water
from the other wells, even though low in mineral content, is predominant
in sodium and chloride ions. In central Escambia County the water from
St. Regis Paper Company wells is low in mineral content and has no
predominant chemical constituent.
Water from the sand-and-gravel aquifer in central Santa Rosa County
has a low mineral content and shows no predominant ions. This section
appears to be the major recharge area for the county. This is indicated
by both the low mineral content of the water and the favorable topo-
graphy.
The water in the northwestern section of Santa Rosa County is mainly
of the carbonate type. The limestone of the Floridan aquifer is closest
to the surface in this area. The water in the 445-foot well (051-652-1)
at the Florida State Forest Nursery near Munson shows the effect of
solution of the fossil shells in the lower part of the sand-and-gravel
aquifer. The water had a total hardness of 116 ppm. This type water, al-
though considered moderately hard and undesirable for some domestic
and industrial use, is excellent for agriculture.
A flowing 535-foot well (058-715-1) at Century is high in carbonate.
This is probably due to contact with a limestone bed just above the
aquifer. The constituents in water from this well are carbonate (89
ppm), sodium (62 ppm), and silica (12 ppm). The water contained
practically no calcium, magnesium, or chloride. The presence of sodium
bicarbonate is probably an example of natural softening. The water dis-
solves the calcium carbonate from the limestone; then by ionic ex-
change the calcium is replaced by sodium from clay lenses, which are
numerous in the sand-and-gravel aquifer. The pH of this water is 8.4. An
earlier analysis of a 305-foot well (058-715-2) in this area shows a water
of a similar type.
In the area just west of and parallel to the Escambia River, from
McDavid to Molino, the sand-and-gravel aquifer is apparently divided
into two or more separate aquifers. Wells in the upper aquifer are non-
artesian and range in depth from about 30 feet in the north to 80 feet
in the south. The lower aquifer produces flowing wells which range in
depth from 125 feet in the north to 282 feet in the south. These flowing
wells result from the pressure of water confined beneath a continuous








REPORT OF INVESTIGATIONS No. 40


confining bed or possibly from numerous lenses of confining material. The
flowing wells are for the most part old, and accurate drilling records and
drill cuttings are not available to define definitely the geologic feature.
However, the gradient defined by the well depth tends to follow south-
ward dip of the formations. Figure 42 shows that mineralization of the


) s SAN T A
4.
C) 30
20 ROSA
^71I


D NK
MNo


1.8e0 I
IAO-
1.20- -
I B OI ll.


080-

060- 60
0.40- =/40
0.20- 20
000- -0
2 3 4 5
WELL NUMBER o04-71B.T o04.i -I 0o4-e20-I 0o0-719-I1 o51-7t-I
Figure 42. Graphs showing chemical composition of water from
sand-and-gravel aquifer from Molino to McDavid.


L CI,F, NO3

s o04


Mg CO%, HCO3



102, in ppm



















wells in the


water increases to the south, indicating longer contact between the water
and the minerals in the ground. This limited evidence suggests the pos-
sible existence of a single confining layer extending over several miles.
The increased mineralization in this area is no real problem because
even the most mineralized water in the aquifer is within the limits of
most municipal and industrial criteria. The only exception is that the
silica content of water from all flowing wells' samples exceeds the maxi-
mum allowable limits for boiler feed water.
Generally, the sand-and-gravel aquifer is a source of water of excep-
tionally low mineral content.


M~~






FLORIDA GEOLOGICAL SURVEY


FLORIDAN AQUIFER
In Escambia and Santa Rosa counties the Floridan aquifer is not
used extensively as a source of water. The sand-and-gravel aquifer is
shallower and supplies sufficient water of better chemical quality.
The Floridan aquifer is used as a source of Water in two locations in
eastern Santa Rosa County, one location near the coast and one near the
Alabama State line. The westernmost water well, No. 028-715-2, (1,561
feet deep) in the upper limestone of the Floridan aquifer was drilled
north of Pensacola in 1957. This well was abandoned when the drill
stem test showed a chloride content of 1,495 ppm. A 950-foot well, No.
022-652-1, drilled at Navarre Beach in 1961, produced water of good
chemical quality. Eglin Air Force Base uses several Floridan aquifer
wells on Santa Rosa Island and many in other parts of Okaloosa County
for water supplies.
In northern Santa Rosa County the well (059-658-1) at Camp Hender-
son Lookout Tower in the Blackwater River State Forest produces water
of good chemical quality from the lower limestone of the Floridan
aquifer.
The Floridan aquifer dips to the southwest and is generally too deep
for practical use. The water downdip in the aquifer tends to become
high in chloride, making it unsuitable for most uses.


USE OF WATER
SURFACE WATER
Only a small part of the surface water of the area is being used. Rec-
reation, shipping, cooling, and waste disposal are the major uses at
present (1962). These uses are nonconsumptive in that no water is
permanently removed from the water body. Water used for cooling is
removed from a stream and returned with only a slight rise in tempera-
ture. There are no known major consumptive uses within the area, and
the full potential of the surface waters is far from being realized.
Most uses of surface water are within the southern half of the area.
Principal among these are recreation and shipping. The 230 square miles
of bays are excellent for boating, fishing, swimming, and other recrea-
tional activities. The Intracoastal Waterway parallels the coast and
allows shipping in protected waters to and from Pensacola harbor. The
Chemstrand nylon plant and the Gulf Power plant use water from the
lower Escambia River for cooling. During the three-year period, 1959-61,
the Chemstrand nylon plant used river water for cooling at the rate of







REPORT OF INVESTIGATIONS No. 40


32.4 mgd. Elevenmile Creek is used for disposal of industrial wastes.
Small storage reservoirs are located on Bayou Marcus Creek to enhance
the value of land.
The surface water within the northern half of the two counties is
virtually unused. Several small dams on the Conecuh River in Alabama
regulate slightly the flow of Escambia River. The Florida Game and
Fresh Water Fish Commission operates a fish hatchery in the Blackwater
River Basin near the Santa Rosa-Okaloosa County line. Some of the many
small ponds in the area are used to water livestock.

GROUND WATER
Information was collected from the various users of ground water
within the area in order to estimate the total amount being withdrawn.
These data are essential to show areas of probable overdevelopment
and areas of potential development. Information on the use of ground
water can be compared with water-level graphs to estimate safe with-
drawals from an area.
SAND-AND-GRAVEL AQUIFER
Almost all the ground water used in Escambia and Santa Rosa coun-
ties comes from the sand-and-gravel aquifer. The estimated daily use of
ground water in both counties is about 87 million gallons-approximately
60,000 gpm. Figure 43 shows the approximate amount of ground water
used daily in the two counties for industrial and public supplies. The
quantities of water are represented by the height of the bars. The illus-
tration shows that most of the water is used in southern Escambia
County and southwestern Santa Rosa County.
Use by industries.-Industries use the largest amount of ground wa-
ter in Escambia and Santa Rosa counties. The industries use ground water
at the rate of about 50 mgd. The estimated daily pumpage by industries
is as follows:
Paper and wood products--------------- 34.5 mgd
Chemical plants ..-------... ------------- ------ 13.9 mgd
Other uses (brewing, laundries, etc.) --------1.6 mgd
The St. Regis Paper Company at Cantonment is the largest user of
ground water in the area. The average daily pumpage is 31 mgd (not
fully metered) from 25 wells. The wells were drilled in 1940, 1941, 1944,
1946, 1947, 1951, and 1957 and range in depth from 158 to 485 feet.
Each well has from one to five well screens. Seven wells have been aban-






FLORIDA GEOLOGICAL SURVEY


doned. One deep well (404 feet) was abandoned because of a high
hydrogen sulfide content and six shallower wells were abandoned be-
cause of declining water levels, partially as a result of close spacing.
The Chemstrand Corporation pumped an average of 7.9 mgd (fully
metered) during 1962. This fgure was reduced from a high of 9.2 mgd
during 1959. The plant started production in the fall of 1953. Records
show an average use during the month of 3.4 in June 1954. This use in-
creased to 9.8 mgd in March 1960. Water conservation measures such as


Figure 43. Map of Escambia and Santa Rosa counties showing the amount of ground
water used daily for industrial and public supplies during 1958 and 1962.






REPORT OF INVESTIGATIONS No. 40


the use of cooling towers, reclaiming steam condensate, and repairing
leaks reduced this pumpage even though nylon production increased.
The average pumpage in January 1962 was 6.3 mgd.
Six wells are used almost full time and three wells are on a standby
basis. The three standby wells are pumped at about 500 gpm because
higher rates cause an increase in the chloride content. One well has
been abandoned because of salt-water encroachment. The wells at the
Chemstrand plant range in depth from 312 to 384 feet and are usually
equipped with two well screens.
The Escambia Chemical Corporation near Pace pumps an average of
2.9 mgd from four wells. The wells are from 260 to 300 feet deep and
were drilled in 1955, 1956, and 1962. The Columbia National Corpora-
tion is also near Pace and just west of the Escambia Chemical Corpora-
tion. Columbia National has one well, 293 feet deep, which is pumped
at approximately 1 mgd.
The American Cyanamid Company has two large-capacity wells,
each capable of pumping more than 1,100 gpm. They also have a smaller
well with a pumping rate of 150 gpm. The three wells were drilled in
1957 and are 278 to 288 feet deep. The present plant use is 1.9 mgd and
the water pumped from the two large wells is metered.
The Newport Industries plant at Pensacola has been in operation
since 1916. Thirteen wells have been drilled between 1915 and 1954.
Seven of these wells have been abandoned due to salt-water encroach-
ment. The chloride content of water from four of the other wells has
shown a gradual increase. The increase in the salt content is very slow
and the water from a well may still be used for several years after the
salt content starts to increase. The chloride content of the water from
two of the wells has not increased. These two wells are farther away
from Pensacola Bay than the other wells.
Newport Industries is presently using five large-capacity wells which
are pumped intermittently. They also use one small-capacity well. The
wells range in depth from 209 to 251 feet. The current use of ground
water is 3.6 mgd. Several cooling towers have reduced the ground-water
pumpage.
Use by municipalities.-The second largest use of ground water in
both counties is for public supply. Seventeen million gallons are used
daily for this purpose. About 16 mgd is withdrawn in the greater Pensa-
cola area.
The City of Pensacola sold ground water at an average rate of 11.4
mgd during 1962 for 75,000 people. This is about 150 gallons of water per
person per day. The water is furnished from ten wells that can be