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STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES
Harmon Shields, Executive Director





DIVISION OF INTERIOR RESOURCES
Charles M. Sanders, Director





BUREAU OF GEOLOGY
Charles W. Hendry, Jr., Chief





REPORT OF INVESTIGATIONS NO. 76





WATER RESOURCES OF WALTON COUNTY, FLORIDA




By
Charles A. Pascale

Prepared by
UNITED STATES GEOLOGICAL SURVEY
in cooperation with
BUREAU OF GEOLOGY
FLORIDA DEPARTMENT OF NATURAL RESOURCES
and
WALTON COUNTY BOARD OF COUNTY COMMISSIONERS


TALLAHASSEE, FLORIDA
1974





DEPARTMENT
OF
NATURAL RESOURCES



REUBIN O'D. ASKEW
Governor


DOROTHY W. GLISSON
Secretary of State



THOMAS D. O'MALLEY
Treasurer



RALPH D. TURLINGTON
Commissioner of Education


ROBERT L. SHEVIN
Attorney General



FRED O. DICKINSON, JR.
Comptroller



DOYLE CONNER
Commissioner of Agriculture


HARMON W. SHIELDS
Executive Director






LETTER OF TRANSMITTAL


Bureau of Geology
Tallahassee
December 5, 1974


Honorable Reubin O'D. Askew, Chairman
Department of Natural Resources
Tallahassee, Florida

Dear Governor Askew:
We are pleased to make available the report "Water Resources of Walton
County, Florida" by Charles A. Pascale. This report should add substantially to
the regional hydrologic picture in the panhandle of Florida. This type of regional
descriptive hydrologic report is most important in providing a general overview
of the water resources capability of an area and is one which is badly needed for
other counties in north Florida. This type of report provides the necessary
background data to be able to evaluate specific problems as they arise, or to
avoid specific problems by proper planning.


Respectfully yours,



Charles W. Hendry, Jr., Chief
Bureau of Geology



















































Completed manuscript received
August 21, 1974
Printed for the
Florida Department of Natural Resources
Division of Interior Resources
Bureau of Geology

Tallahassee
1974



iv






CONTENTS


Abstract ....................................
Introduction ..................................
Location and extent of area .....................
Purpose and scope ...........................
Data collection ............... ...............
Acknowledgements ..........................
Hydrologic setting ................. ....... .
Clim ate ................................
Physiography ..............................
Geology ........ ..........................
Sand-and-gravel aquifer . . . . . .
Floridan aquifer .........................
Confining beds ..........................
Water resources ..................... . .
Ground water .............................
Occurrence and movement ..................
Aquifers ........ .................. ..
Sand-and-gravel aquifer .................
Water-level fluctuations ..............
Quality of water ..................
Floridan aquifer ......................
Discharge from the Floridan aquifer ... ...
Water-level fluctuations ........... ....
Aquifer characteristics . .. . .
Quality of water ................. .
Surface water ...... .... .................. .
Occurrence of streamflow ..................
Stream s ..............................
Lakes ...............................
Quality of water .........................
Water use and availability .... .... ..............
Suggestions for further study .....................
Summary and conclusions ...... ..............
References .......... .........................
Appendix ...................................


Page

. .. 1
3
S 3
3
S 5
6
6
6
8
... 10
S. 10
S. 15
* 15
... 15

. 16
* 16

S.. 16

S.. 19
S. 19
. 19
... 20

... 24
. 24
S. 25
. 27
... 30
S. 36

... 36
. 36
... 46
... 47
... 53
... 56
... 56
... 59
... 61





ILLUSTRATIONS

Figure Page
1. Map showing locations of hydrologic data-collection sties and generalized
physiographic divisions of Walton County . . . ... 4

2- Graphs showing average monthly rainfall and temperature at DeFuniak
Springs, 1897-1970 . . . ..... . . . 7

3. Graph showing annual rainfall at DeFuniak Springs, 1897-1970 .... ... 8

4. Map showing locations of core holes and cross sections referred to in other
illustrations and text of report ............................ 11

5. Hydrogeologic section A-A' through western Walton County .. . ... 12

6. Hydrogeologic section B-B' through central Walton County . . ... 13

7. Hydrogeologic section C-C' through eastern Walton County ........... 14

8- Map of the potentiometric surface of the Floridan aquifer, March 9-13, 1970 17

9. Map of the potentiometric surface of the Floridan aquifer, June 22-26, 1970 18

10. Hydrographs showing water levels in selected wells that tap the sand-and-gravel
aquifer and graph of monthly rainfall at DeFuniak Springs . . .... 21

I1. Map showing selected constituents of ground water and depth of wells tapping
the sand-and-gravel aquifer ................. ............. 22

12. Hydrographs showing water levels in wells that tap the Floridan aquifer and
graph of monthly rainfall at DeFuniak Springs . . . ..... 25

13. Hydrograph showing water level in well 22 that taps the Floridan aquifer ... 26

14. Hydrographs showing water levels in wells that tap the Floridan aquifer at
Owl's Head Farm ................... .. ............. 28

15. Map of the net decline of potentiometric surface of the Floridan aquifer from
March 9-13 to June 22-26, 1970 ........................... 29

16. Map showing transmissivities and storage coefficients at wells that tap the
Flridan aquifer .................................... 31

17. Map showing dissolved solids in water from wells that tap the Floridan aquifer 34

vi






ILLUSTRATIONS Continued

Figure Page
18. Map showing chloride content of water from wells that tap the Floridan aquifer 35

19. Graphs showing chloride content of water from Floridan aquifer wells in
Walton County . . . . . . . ... 37

20. Hydrographs showing daily flow of three streams in Walton County,
March-May 1970 ....... ... ........ ........ ........... 40

21. Flow-duration curves for major streams in Walton County ........... .. 41

22. Graph showing magnitude and frequency of low flow at Alaqua Creek near
DeFuniak Springs, 1952-70 ...... ................ ......... 42

23. Graph showing magnitude and frequency of low flow at Shoal River near
Mossy Head, 1952-70 ............... ........ ............ 43

24. Graph showing magnitude and frequency of low flow at Choctawhatchee
River near Bruce, 1931-70 .................... ........... 44

25. Map showing stream discharge and dissolved solids, May 14-26, 1970 ..... 45

26. Graph showing regionalized flood-frequency curves for Shoal River Basin and
basins between Choctawhatchee River and Yellow River ....... ..... 46

27. Month-end level of Lake Jackson near Paxton, 1966-70 ...... ..... 49

28. Graph showing variation in specific conductance of selected streams and
discharge of Magnolia and Seven Runs Creeks ........... ....... 51






TABLES

Table Page
1. Quality of Floridan aquifer wells in Walton County ............ .32

2. Summary of streamflow data at gaging sites in Walton County ...... 38

3. Quality of Water in Walton County streams . . . ..... 48

4. Differences in significant characteristics of selected streams, October
1969-September 1970 ............................. 52

5. Pesticide analyses for water and bottom sediments from Magnolia Creek 54

6. Surface-water data-collection sites in Walton County . . .... Appendix

7. Ground-water data-collection sites in Walton County . . .... Appendix

8. Factors for converting English units to International System (SI) units Appendix






WATER RESOURCES OF WALTON COUNTY, FLORIDA


By
Charles A. Pascale


ABSTRACT

Walton County is an area of about 1,140 square miles in northwestern
Florida. In 1970 the population of the county was 16,087. Ground-water use
averaged about 13.2 mgd (million gallons per day) and most of it was used for
irrigation-10 mgd or about 11,000 acre-feet per year. Surface water is not a
significant supply.

The county receives abundant rainfall, 65 inches per year on the average,
at DeFuniak Springs. Much of this water enters the sand-and-gravel aquifer, then
seeps to streams, or enters the underlying artesian Floridan aquifer.

The two major aquifers in Walton County are the sand-and-gravel aquifer
and the Floridan aquifer. The sand-and-gravel aquifer supplies some water for
rural domestic use. It is an important aquifer because it stores water, maintains
streamflow, and is a source of recharge to the Floridan aquifer. Water from the
sand-and-gravel aquifer ranges in dissolved solids from 20 to 120 mg/1
(milligrams per liter), in pH from 5.3 to 6.9, and in iron content from 0.1 to 5.0
mg/1.

The Floridan aquifer underlies all of Walton County and is the primary
source of water supply. Wells generally yield 500 to 1,000 gpm (gallons per
minute) except along the gulf coast where the yield is less because the
permeability of the aquifer is low. The transmissivity of the Floridan aquifer is
highly variable and ranges from 4,000 gpd (gallons per day) per foot along the
gulf coast to 180,000 gpd per foot in southeastern Walton County; the
coefficient of storage ranges from 1.6 x 10T4 to 5.6 x 1(T4. The aquifer is
recharged by downward leakage of water from the sand-and-gravel aquifer where
the water table in the sand-and-gravel aquifer is higher than the potentiometric
surface of the Floridan aquifer; and where the clay confining beds that separate
the two aquifers are permeable, thin, or breached. In southern Alabama the
Floridan is recharged directly by rainfall. There the Floridan is exposed or is
near land surface. Ground-water moves southward and away from the
potentiometric high in northwestern Walton County. The aquifer discharges
through springs and seeps along Choctawhatchee River, by leakage to the bay
and gulf, and by wells.





BUREAU OF GEOLOGY


In southern Walton County water levels in the Floridan aquifer declined
about 0.25 foot per year from 1948 to 1968 because of increased water use. In
1968 levels declined sharply owing to a lack of recharge to the aquifer and heavy
seasonal pumpage for irrigation. Pumpage for irrigation in 1970, from farm wells
in southeastern Walton County, caused water levels there to decline more than
80 feet. The cone of influence generated by this large seasonal pumpage
extended outward for more than 10 miles and increased natural recharge to the
Floridan aquifer. Water levels remained above sea level in the coastal areas and
all water levels recovered to about normal after the irrigation season.

Saline water (more than 1,000 mg/l of dissolved solids) occurs naturally at
depth within the Floridan aquifer throughout all of Walton County. The
elevation of the fresh-water-saline-water interface in the aquifer ranges from
about 650 feet below sea level in the northeastern part of the county to 1,200
feet below in the southwestern part. Saline water at relatively shallow depths
along the coast limits useful well-bottom elevations to about 500 feet below sea
level.

Dissolved solids in water from wells tapping the Floridan aquifer in Walton
County range from 70 to 3,500 mg/1 and chloride, from 1 to 2,000 mg/l. In
water from north of Choctawhatchee Bay, dissolved solids is less than 150 mg/1
and chloride, less than 10 mg/l. In water adjacent to Choctawhatchee Bay,
dissolved solids range from 500 to 3,500 mg/l and chloride, from 150 to 2,000
mg/l; both constituents increase in amount with well depth. Along the central
gulf coast, wells drilled to less than 500 feet below sea level generally contain
water whose chloride content is less than 250 mg/l. Water of excellent quality is
available from the Floridan aquifer along the coast in a little used zone about
100 feet thick and generally less than 100 feet below land surface.

Streams originating in Walton County discharge on the average about
1,000 mgd; minimum discharge during dry spells is about 300 mgd. Although
most streams yield copious amounts of water of good quality, none are used for
water supply. Mineral content is relatively low, averaging 20 mg/l; pH ranges
from 4.7 to 7.9, color, from 4 to 50 platinum-cobalt units, and turbidity, from
3.1 to 25 Jackson turbidity units. Dissolved-solids content of Magnolia and
Seven Runs Creeks increased by about 45 mg/1 due to return flow of irrigation
water.

There are about 25 named lakes in Walton County that range from 10 to
400 acres in surface area. Most are used primarily for recreation. Lakes along the
coast are brackish and those inland contain water with dissolved-solids content
usually less than 20 mg/1.






REPORT OF INVESTIGATION NO. 76


INTRODUCTION

In 1968, northwestern Florida experienced a record-breaking drought
which caused record-low surface-water discharge. The drought caused increased
ground-water use which resulted in record-low water levels in wells tapping the
Floridan aquifer. In southern Walton County artesian wells ceased to flow, some
wells went dry, and intakes of many pumps had to be lowered.

Ground-water use has increased rapidly during the last few years. In
southeastern Walton County, 27,000 acres of land were developed for
agriculture during 1968 and more than 80 large-capacity wells were drilled into
the Floridan aquifer to irrigate this land. Recent increase in commercial and
domestic demand for water along the gulf coast is hastening the development of
ground-water supplies.

The problems caused by the increased water use brought to the attention
of area water planners the need for water-resource information. They needed to
know whether the low water levels were permanent, where to obtain more
water, and what effect increased water use would have on salt-water encroach-
ment of the Floridan aquifer along the coast.

LOCATION AND EXTENT OF AREA

Walton County is in northwestern Florida (fig. 1). The county extends
from the gulf to Alabama and is bordered on the west by Okaloosa County, and
on the east by Holmes, Washington, and Bay counties.

The area of Walton County is 1,140 square miles, including 85-square-mile
Choctawhatchee Bay. Eglin Air Firce Base includes about 240 square miles in
southwestern Walton County. In 1970 the population of the county was 16,087.
DeFuniak Springs, the county seat and largest city in the county, had a
population of 4,966.

Agriculture is the principal industry in the area. Corn, soybeans, grain
sorghum, and wheat are the principal crops. Much of the county is covered with
commercial pine forests. Tourism is important along the coast.

PURPOSE AND SCOPE

Recognizing the need for water-resources information, the Walton County
Board of County Commissioners and the Florida Department of Natural
Resources, Bureau of Geology, entered into a cooperative agreement with the
U.S. Geological Survey to investigate and report on the hydrology of Walton
County, Florida.







BUREAU OF GEOLOGY


i 20W
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SHADED SYMBOL INDICATES
CONTINUOUS RECORD. NON- SHADED
SYMBOL INDICATES PERIODIC OR
INTERMITTENT RECORD

SCOS1IL LOWLANDS, 0 O 00
FEET ABOVE SEA LEVEL,
(AFTER COOKE, 1939
] WESTERN HIGHLANS, 00 TO
34 FEET ABOVE SEA LEVEL.
S AFTER COOKE 19311


0 I I
o 1I 0 IS


MILES

KILOMETERS


Figne 1. Map showing locations of hydrologic data-collection sites and
generalized physiographic divisions of Walton County.


2l 2W


I






REPORT OF INVESTIGATION NO. 76


This report evaluates the water resources of the county and provides
information that will aid in the development and use of ground and surface
water for current and future needs. It also provides information concerning the
potential for salt-water encroachment of the Floridan aquifer.

The field studies began in the summer of 1968 and continued through
September 1970. Some records of streamflow, ground-water levels, and water
quality had been collected for Walton County as part of the statewide
data-collection program. Other records were collected as part of this project.
Figure 1 shows the sites where hydrologic data were collected and tables 6 and 7
(Appendix) describe the sites, the types of data, and periods of record. The
long-term streamflow records and chemical analyses of surface water are
published by the U.S. Geological Survey in an annual series of Water-Supply
Papers. Other data collected during the investigation have been published
(Pascale, Essig, and Herring, 1972).

DATA COLLECTION

An observation-well network, established July 1968, was operated for 2
years. Recording water-level gages were maintained on six wells. Water levels in
an additional 30 wells were measured at 4- to 8-week intervals. Water from
selected wells was analyzed for chemical content. Supplemental data were
collected from more than 160 wells which tap either the sand-and-gravel or
Floridan aquifer.

Five surface-water gaging stations (two daily and three monthly) were
established September 1968 to complement three long-term daily gaging stations
located in the county. Annual mean discharges were estimated from monthly
discharge measurements made at the three monthly gaging stations (Riggs,
written commun., 1968). The average flows for the daily discharge stations were
adjusted to a common base period (1931-70). Streamflow measurements were
also made annually at miscellaneous sites. Water samples were collected
semiannually from streams at gaging station sites for analysis of chemical
content and monthly for temperature and specific conductance. Water samples
from streams at all the project gaging station sites in October 1969 and
September 1970 were analyzed for total coliform bacteria. Pesticide analyses
were run on samples taken from Magnolia Creek twice during the study.

Three rainfall gages were established within the county to extend the
rainfall-data coverage already available.

Aquifer tests were made at 10 wells. Selected wells were logged to
determine the physical well characteristics (depth of casing, bore-hole diameter,





BUREAU OF GEOLOGY


depth of well, and lithology), and to try to delineate a zone of saline water
known to occur within the aquifer. Geologic logs of selected core holes and wells
made available by the Florida Bureau of Geology were used to map the top of
the Floridan aquifer. Logs of oil test wells were used to determine the depth to
the fresh-water-saline-water interface.

ACKNOWLEDGEMENTS

Appreciation is extended to the many individuals who furnished informa-
tion on their wells and who gave access to their land and equipment for
measurements and tests. First American Farms, Inc. made their irrigation
equipment and wells available for aquifer tests and their wells for ground-water-
level measurements.

Mr. C.W. Hendry, Jr., Florida Department of Natural Resources, Bureau of
Geology, made available the descriptions of more than 25 well cores taken in
Walton County. They were invaluable in mapping the geology of the study area.

The cooperation and courtesies extended by the following persons were
outstanding: Gus Hatch, Leonard Perkins, Terrance Williams, and Lewis Miller.
Thanks are also extended to Conley Martin and the other members of the
Walton County Board of Commissioners who cooperated in all aspects of the
investigation.

The author is indebted to his colleague, Carl F. Essig, Jr., for his assistance
in the collection of hydrologic data.


HYDROLOGIC SETTING

Climate, physiography, and geology control the availability of water.
Climate determines the amount of fresh water that reaches the land surface as
rainfall while physiography and geology govern the amount and rate of runoff
and infiltration. Rainfall in Walton County that is not lost to evapotranspiration
is absorbed by porous soils and eventually replenishes the aquifers; or it is stored
in lakes or ponds, or flows overland in streams as surface water. Rain which falls
outside the county may enter the county as ground or surface water.

CLIMATE

Walton County has a warm humid climate. The average annual air
temperature at the NWS (National Weather Service) station in DeFuniak Springs
is 69F. The average monthly air temperature ranges from 550F in December
and January to 820F in July and August (fig. 2). Average monthly rainfall ranges





REPORT OF INVESTIGATION NO. 76


from 3.2 inches in October to 8.8 inches in July (fig. 2). Nearly half the yearly
rainfall occurs between June and September as a result of thunderstorms and
tropical depressions.


J F M A M J J A S O N D


Figure 2. Graphs showing average monthly rainfall and temperature at
DeFunlak Springs, 1897-1970.

Annual rainfall at DeFuniak Springs from 1897 to 1970 averaged 65
inches and ranged from 38 inches in 1954 to 94 inches in 1947 (fig. 3). An
annual rainfall of 65 inches uniformly distributed throughout Walton County is






BUREAU OF GEOLOGY


equivalent to 3.3 bgd (billion gallons per day). During 1968 and 1969 when most
of the hydrologic data for the investigation were collected, the 2-year cumulative
rainfall was 99.41 inches or about 30 inches below average.

During the investigation annual rainfall was as much as 10 inches greater at
some places in the county than it was at DeFuniak Springs. This difference was
due to isolated storms-a data variation which is equalized in long-term records.


RAINFALL INCHES

So -4 0 o
0 0 0 0 0 0 0


Figure 3. Graph showing annual rainfall at DeFuniak Springs, 1897-1970.



PHYSIOGRAPHY

Walton County is included in two of Cooke's (1939, p. 14) topographic






REPORT OF INVESTIGATION NO. 76


divisions of Florida, the Coastal Lowlands and the Western Highlands (fig. 1).

The Coastal Lowlands include the white-sand beaches and sand-dune ridges
along the coast and the swamps and flatwoods that extend inland 10-15 miles.
The Lowlands generally range in elevation from sea level to 100 feet. The sand
ridges, formed by wind and wave action, rise sharply from the beach and extend
inland from one-half to 1 mile and then slope gradually toward Choctawhatchee
Bay. At Blue Mountain Beach, dunes are more than 70 feet high. Numerous
creeks and lakes along the ridges connect with the gulf. Most of the lakes are
brackish because water from the gulf moves into them during severe storms.
According to Martens (1931, p. 112), they were at one time bays or inlets of
which the mouths have been nearly closed by sand bars.

The swamps and flatwoods are in an area adjacent to Choctawhatchee Bay
and River that extends approximately 15 miles north from the coast. The
swamps include the low, poorly drained areas south of Choctawhatchee Bay and
the flood plain of the Choctawhatchee River, usually less than 30 feet above sea
level. The flatwoods format area north of the bay is generally well drained by
small streams which discharge into the bay.

The Western Highlands extend northward from the Coastal Lowlands into
Alabama. The southern part includes the gently rolling sandhills which range in
elevation from 100 to 250 feet above sea level. The northern part includes the
swampy bays in the north-central and the hilly section along the Alabama line
where elevations are as much as 345 feet above sea level.

The sandhill area is characterized by the steepness of the heads of many
streams that drain the area. According to Sellards (1918, p. 27), "These
steepheads are due to the fact that indurated sands and sandy clays overlie
slightly indurated sands and clays and shell marls. The surface waters pass into
the earth and, upon reaching the underlying clay or marl beds, emerge as springs.
The indurated sandy clays near the surface stand up vertically, while the softer
sands, at a greater depth where the springs emerge wash easily. The result is the
formation of a nearly vertical bluff, at the base of which springs emerge,
supplying small streams. This bluff or streamhead assumes in time a semicircular
form, which is the 'steephead'." Due to this active undermining at the base of
the "steepheads," bluffs eventually collapse and the streams move headward.

A characteristic of the Western Highlands is the nearly circular lakes of
central Walton County. Cooke (1939, p. 17) suggested that these lakes were
originally sinks formed when the ground-water level was much lower than
present and the downward movement of rainwater was more active. As water
levels rose to their present positions, ground water flooded the deep sinks and
converted them into lakes and ponds.





BUREAU OF GEOLOGY


In the northern part of the county, bay sinks developed in depressions
formed by the collapse of the underlying limestone. The sandy clay and marl
which filled the depressions are low in permeability; the depressions remain wet
most of the time. That part of the county north of the bay sinks is hilly:
Florida's highest land elevation, 345 feet above sea level, is near Paxton.

The county is drained by several large rivers and by many small streams.
Shoal River heads in the northern part of the county and drains south and
southwest into Yellow River in Okaloosa County which empties into Blackwater
Bay in Santa Rosa County. Eightmile Creek also heads in northern Walton
County; it flows north into Alabama where it discharges into Pea River, a
tributary to Choctawhatchee River. Alaqua Creek, Lafayette Creek, Black Creek,
Basin Creek, and Rocky Creek drain most of the sandhill area south of DeFuniak
Springs and discharge into Choctawhatchee Bay. Sandy Creek, Seven Runs
Creek, and Bruce Creek drain most of the eastern half of the county to
Choctawhatchee River.

GEOLOGY

Walton County is underlain by two major hydrogeologic units. The upper
unit is the sand-and-gravel or unconfined aquifer (Musgrove, Barraclough, and
Marsh, 1961, p 11). Below the sand-and-gravel aquifer, and for the most part
separated from it by layers of clay and marl, are the limestones of the Floridan
aquifer.


SAND-AND-GRAVEL AQUIFER

The sand-and-gravel aquifer consists primarily of quartz sand of Miocene
age that ranges in color from white to brown and in size from fine to very
coarse. Lenses of coarse to very coarse pea gravel mixed with sand are found
throughout the aquifer. Usually a small quantity of clay is also present in the
sand and acts as a coloring and cementing agent, adhering to the sand grains.
Stringers of white to purple clay are scattered throughout the aquifer.

The sand-and-gravel aquifer extends throughout the county, as shown by
the generalized geologic sections in figures 4 through 7. It is thickest in the
west-central part of the county and gradually thins to the north and east. In the
north, the aquifer is divided into an upper and lower section by a layer of clay
and marl which pinches out south of U.S. Highway 90.








REPORT OF INVESTIGATION NO. 76


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LINE OF CROSS SECTIONS SHOWN
IN FIGURES S,,*AND7.


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Figure 4. Map showing locations of core holes and crom sections referred
to in other illustrations and text of report.






















A!




POTENTIOMETRIC SURFACE OF a
THE FLORIDAN AQUIFER n
(Mwch 1970)

-- -- -_ -0



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40






POTENTIOMET1iC
THE FLORIDAN
AQUIFER
(MARCH 1970)
200' 20




SEA MEAN SEA
LEVEL LEVEL


0 I 2 3 4 5 MILES
S(Veirtifcal Ksca gredly xmaggriawd)


20d




400'




600'


PFos 6. Hydrog ologic section B-B' trough centnl WalIn County.


200'




400'




600'


EXPLANATION
FLORIDAN CFI CONFININGO BED SAtD-ANO-GRAVEL
AQrID aFER CONIy and BEDrl) A (Clay Maol and AOUFER (Snd.
r1 Cst)lay ad Ma) sad)i Gol W Clay)















a










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B.B I.







POTERTIOMETRI 9
SURFACE OF THE
FLOAIOAN oZ
AQUIER (Ma0rch
1970)- -





.. .. j- -- -- -
- -t'


Figure 7. Hydrogeologic section C- through eastern Walton County.


400'






200'






MEAN SEA
LEVEL

C








200'
o




400


400'






200'


SEA
LEVEL






200'






400'






600'


EXPLANATION

FLOIDAN F7 CNWWING stA LE SAND-yND-
WINFE SAALE ST am. (Ca AQUER LS,,
jER SAND BED (Clay) __ AND CLAY 3 5 AND SAND Mrl oan AQUIFER (SandO
(L mn)-l S SOW)l and Clay)


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REPORT OF INVESTIGATION NO. 76


FLORIDAN AQUIFER

The Floridan aquifer is the principal source of ground water in Walton
County. It was first described by Stringfield (1936) and later named the
Floridan aquifer by Parker and others (1955, p. 189). The Floridan aquifer
underlies all of Florida and parts of the adjacent States of Georgia and Alabama,
and it ranges in age from middle Miocene to upper Eocene.

In south-central Walton County two sequences of limestone, separated by
layers of clay and marl (figs. 5-7), are present. The upper sequence is thickest in
the south and gradually pinches out to the north. C. W. Hendry, Jr. (written
commun., 1968) described the upper limestone sequence as yellowish gray, very
finely crystalline, sandy, and microfossiliferous with lenses of clay and marl
commonly intermixed throughout. He identified it as a part of the Chipola
Formation of the lower Miocene Series.

Below the Chipola Formation, separated by Miocene clay, is the Suwannee
Limestone which underlies all of Walton County. Hendry (written commun.,
1969), identifies the Suwannee Limestone as composed of yellowish brown to
brown dolomitic limestone, hard, and with varying porosity. The Suwannee
Limestone is part of the Oligocene Series.

Below the Suwannee Limestone is limestone of the Ocala Group which
underlies all northwest Florida. The Ocala Group is part of the upper Eocene
Series; its limestone is white to grayish cream and rather soft and chalky. It
contains lenses of hard, light-gray shale (Musgrove, Barraclough, and Marsh,
1961,p. 18).

The Suwannee Limestone is separated from the overlying Chipola
Formation by sand and clay. It grades into the limestone of the underlying Ocala
Group; the contact between the Suwannee Limestone and Ocala Group has not
been determined. In this report the Floridan aquifer is considered to include the
Chipola Formation, the Suwannee Limestone, and the Ocala Group.

The Floridan aquifer is underlain by shale and clay of middle Eocene age
(Musgrove, Barraclough, and Marsh, 1961, p. 18) which dips generally
southwestward-it ranges in depth from about 600 feet below sea level at the
Alabama State line to about 1,000 feet below sea level at the coast.

CONFINING BEDS

Layers of relatively impermeable clay and marl occur throughout the
aquifers (figs. 5, 6, and 7) and reduce average permeability of the aquifer. Where
they occur as confining beds, they retard the movement of water between





BUREAU OF GEOLOGY


aquifers and develop an artesian head in the confined aquifer. The clay and marl
beds range in thickness from a few inches to more than a hundred feet. The clay
varies from dark olive gray to brownish black and from firm plastic to medium
sandy. The marl is yellowish gray to olive gray and is soft to firm.


WATER RESOURCES

GROUND WATER

OCCURRENCE AND MOVEMENT

Ground water that is not returned to the atmosphere by evaporation and
transpiration moves from areas of recharge (high, relatively flat, sandy ground)
to areas of discharge (streams, wells, the gulf); the moving force is gravity.

Ground water in the sand-and-gravel aquifer is not confined-that is, its
potentiometric surface or water table is said to be under nonartesian conditions.
Water in the Floridan aquifer is confined and its water level or potentiometric
surface rises above the top of the aquifer in a well and in some cases above land
surface (a flowing artesian well).

The sand-and-gravel aquifer is recharged directly by rainfall and the shape
of the water table is related to topography. Water that reaches the aquifer moves
toward areas of lower elevation. Ground water is discharged from the aquifer
through seeps and springs to streams, to evapotranspiration, by leakage to the
underlying Floridan aquifer and by pumping of wells.

In Walton County the Floridan aquifer is recharged by downward leakage
of water from the sand-and-gravel aquifer where the water table in the
sand-and-gravel aquifer is higher than the potentiometric surface of the Floridan
aquifer; and where the clay confining beds that separate the two aquifers are
permeable, thin, or breached. In southern Alabama it is recharged directly by
rainfall where the Floridan is exposed or is near land surface.

The shape of the potentiometric surface of the Floridan aquifer varies
during the year. In the spring the potentiometric surface of the Floridan slopes
smoothly, mostly toward the south (fig 8). In the summer, when discharge from
the aquifer is at a maximum, the potentiometric surface slopes sharply toward
the area of heavy withdrawal (fig. 9).







REPORT OF INVESTIGATION NO. 76


A21W ,R20W R19W RIS W 0
B6"IS 86'00'


RI? W


I I


I I

EXPLANATION


-- 50O
POTENTIOMETRIC CONTOUR SHOWS
ELEVATION OF POTINTIOMITRIC
tUFICE, CONTOUJ INT(EVAL II
10 PEET. DATUM IS MEAN SEA
LEVEL.



INPIREO DIRECTION of ORDOUND-
WATER FLOW.


30o15--


10 MILES

S10 KICWTERS



Figure 8. Map of the potentiometric surface of the Ploridan aquifer,
March 9-13, 1970.


3100
T6N




TSN







T4N







45
T3N






T2N







TIN






30'
TIS







T2S







BUREAU OF GEOLOGY


R 21W R20W
*EIS'l


RI W RI W R 17 W
a6eoo


SI i I I


POTENTIOMETRIC CONTOUR SHOWS
ELEVATION OF POTENTIOMUETRIC
SURFACE. CONTOUR INTERVAL IS
10 FEET. DATUM IS MEAN SEA
LEVEL.



INFERRED DIRECTION OF gROUND-
WATER FLOW.


301i'-


0 10 MILES

0 S 10 a KILOMETERS



Flpoe 9. Map of dhe potentiometic safce of the Flaodan aquifer, June
22-26, 1970.






REPORT OF INVESTIGATION NO. 76


The potentiometric surface of the Floridan aquifer normally ranges from
more than 190 feet below land surface in northern Walton County, in areas
where land elevations exceed 300 feet, to 20 feet above land surface in southern
Walton County, where land elevations are less than 10 feet above sea level (figs.
5, 6, and 7). Where the potentiometric surface is above land surface, wells that
tap the aquifer flow. Wells flow in most areas near Choctawhatchee Bay and the
gulf coast, and also in low areas along the Choctawhatchee River. When use of
ground water is high, the potentiometric surface declines below land surface and
wells stop flowing.

Ground water moves downgradient away from the potentiometric high in
northwestern Walton County (fig. 8). The rather flat gradient in the southeastern
part of the county probably reflects the higher permeability of the limestone in
that area (fig. 16) where, on the basis of individual aquifer tests, transmissibility
is as high as 180,000 gpd per foot.

The Floridan aquifer discharges naturally by leakage to the bay and gulf,
to the Choctawhatchee River, and through seeps and springs in areas where the
potentiometric surface is above the land surface and the aquifer's confining bed
is breached or missing. The aquifer is discharged also through pumping or
flowing wells. The depressions in the potentiometric surface shown in figure 9
for June 1970 are a result of large withdrawals of ground water from the aquifer
for irrigation.

AQUIFERS

SAND-AND-GRAVEL AQUIFER

The sand-and-gravel aquifer is used mostly for rural-domestic supplies. It
does not now constitute a primary source of water supply in Walton County. Its
importance will begin to grow as supplies from the Floridan aquifer diminish or
become more expensive. The sand-and-gravel aquifer is highly permeable except
where it contains clay. Wells that tap this aquifer range in depth from 25 feet to
165 feet and yield from 5 to 30 gpm (gallons per minute), which is generally
sufficient for domestic uses. The present importance of the sand-and-gravel
aquifer stems from its capacity to store water, to maintain streamflow, and to
supply water to shallow wells and to the Floridan aquifer. The sand-and-gravel
aquifer is a tremendous reservoir that, in Walton County, contains about
20,000,000 acre-feet of potable water.

Water-level Fluctuation

Water levels in the sand-and-gravel aquifer rise when rainfall is sufficient to
recharge the aquifer. Water levels decline when recharge is less than leakage.





BUREAU OF GEOLOGY


Hydrographs of sand-and-gravel wells 92, 96, 100, and 104 (fig. 1) and
monthly rainfall at DeFuniak Springs are shown in figure 10. Well 104, which is
not affected by pumping, reflects natural fluctuations of the water level and
shows the influence of rainfall on water levels in the aquifer. The minimum
water level at year end 1968 represents the culmination of a 2-year drought.
From January 1969 to September 1969, when rainfall was about average, the
water level rose about 14 feet. From April to September 1969 wells 92, 96, and
100 were affected by the pumping of nearby Floridan aquifer irrigation wells.
Pumping from individual wells in the Floridan varied according to the need for
water by the various crops. The water level rose in sand-and-gravel aquifer well
100 from April through July 1969 due to irrigation of a corn field surrounding
well 100. The high-water level in June 1970 at wells 92 and 100 was caused by
application of excess water to irrigate crops near these two wells, and from
above average rainfall during June. During 1970, pumping for irrigation did not
begin near well 96 until August.

Quality of Water

The water in the sand-and-gravel aquifer is generally of good quality and in
most respects meets standards for drinking water. Concentrations of dissolved
solids and chloride are usually less than 25 mg/l; some wells produce water with
excessive amounts of iron in solution. A map showing some selected chemical
constituents of water from wells penetrating the sand-and-aravel aquifer,


Both chloride and dissolved-solids concentration are used as an index of
water mineralization. Chloride is in all natural waters; usually the concentrations
are low (Hem, 1970, p. 172). U.S. Public Health Service (1962) recommends
that water for domestic use should not exceed 250 mg/1 of chloride or 500 mg/1
of dissolved solids. Hem (1970, p. 323) reports, however, that for the lack of
better water, some people have used water whose chloride or dissolved-solids
concentration is substantially in excess of the limits recommended by the U.S.
Public Health Service with no apparent detrimental effects to the users.

Because the unconsolidated quartz materials which make up the sand-and-
gravel aquifer are insoluble, the dissolved-solids concentration in the water from
that aquifer is usually low. In water from wells along the coast, the
dissolved-solids concentration ranges from 20 to 128 mg/l.

Chloride concentrations range from 0.8 to 26 mg/l and are highest in water
from wells adjacent to the coast, probably because of saltwater contamination in
the lower part of the aquifer. Coastal rain also contains small amounts of
chloride acquired over the Gulf.






REPORT OF INVESTIGATION NO. 76


165 i I .. .I I I m I I I I I ' ',
WELL 96
Depth 18 ft.
160



135 1 1 1 1 1 F I I
WELL 100
Depth 32 ft.
130



155 I I
WELL 104
Depth 60ft.
150 -


145



140 i


o DEFUNIAK SPRINGS M _


w
U

I,






8 m

.-J
27 -


32
42



32


57



42


1968 1969 1970


Figure 10. Hydrographs showing water levels in selected wells that tap the
sand-and-gravel aquifer and graph of monthly rainfall at De-
Funiak Springs.


_3

4-
I.A
Zc









* tIA


BUREAU OF GEOLOGY

W IN W*tI WOSH


W ISR


t81aM


Figure 11. Map showing selected constituents of ground water and depth of
wells tapping the sand-and-gavel aquifer.





REPORT OF INVESTIGATION NO. 76


The iron concentration in the water ranges from less than 0.1 to 5 mg/l.
According to the U.S. Public Health Service (1962), more than 0.3 mg/1 of iron
is undesirable as it stains plumbing fixtures, clothing, and imparts an unpleasant
taste and color to the water. The reaction of iron oxide in limonite clay
interbedded in the aquifer, with the acidic water (pH, 5.3 to 6.9) is probably
responsible for the high iron concentration of the water. Other possible sources
of iron in water from wells that tap the aquifer are iron pipe, storage tanks, and
fittings that are in constant contact with the water. The low pH of the water
makes it corrosive and the iron readily dissolves.

FLORIDAN AQUIFER

The Floridan aquifer underlies all of Walton County and is the primary
source of water in the county. It is composed of permeable and porous
limestone which contains large quantities of ground water. Wells tapping this
aquifer commonly yield 500 gpm to as much as 1,000 gpm.

The top of the aquifer ranges from 50 feet below land surface in the
northeast part of Walton County to 300 feet below in the midwest part. The
aquifer ranges in thickness from about 700 feet in the north to about 1,000 feet
in the south.

Discharge from the Floridan Aquifer

A significant quantity of ground water discharges naturally along
Choctawhatchee River where the aquifer is exposed by erosion. The potentio-
metric level of the Floridan aquifer is usually greater than the elevation of the
water surface along the entire reach of the river.

A channel-bottom profile was made with a fathometer near the mouth of
the Choctawhatchee River. Many large and deep depressions were detected in
the channel bottom, some of which were 40 feet or more below the normal
channel profile. That these depressions remain unfilled near the mouth of the
river, where stream velocities are low and in a river whose storm runoffis heavily
laden with sediment, suggests that groundwater discharge is great enough to keep
the depressions open.

Morrison Spring, on the west bank of the Choctawhatchee River (fig. 1), is
another example of natural discharge from the Floridan aquifer. The spring
normally discharges through numerous channels into a swamp and then into
Choctawhatchee River, but at low flow the discharge is confined to one channel
and thus measurable. During the drought of the summer of 1968 the level of the
Choctawhatchee River was near its record low and Morrison Spring discharge





BUREAU OF GEOLOGY


was measured at 83 cfs (cubic feet per second) or 54 mgd (million gallons per
day).

Until 1968, withdrawals from wells by pumping and by artesian flow
increased gradually, mostly along the gulf coast and for domestic use. In 1968,
large-scale farming began and ground-water withdrawals for irrigation immedi-
ately exceeded the total withdrawals for domestic uses up to that time. More
than 80 high-capacity (800-1,000 gpm) wells were constructed in the Floridan
aquifer to irrigate about half of the 27,000 acre Owl's Head Farm located 5
miles north of Freeport and east of U.S. Highway 331. In 1969, six 800-gpm
wells were drilled to irrigate about 1,000 acres of the 3,000-acre Mossy Head
Farm, 5 miles north of Mossy Head.

The irrigation wells on the Owl's Head Farm range in depth from 400 to
550 feet; most have 190-220 feet of 12-inch casing then open hole into the
Floridan aquifer. On Mossy Head Farm the wells average about 700 feet deep;
most have 300-350 feet of 12-inch casing and openhole into the Floridan
aquifer. Most of the wells are arranged in a network of four wells per square mile
and each well is equipped with an automatic circular self-propelled sprinkler
system which requires between 60 to 70 hours of continuous discharge
(800-1,000 gpm) to apply a 1-inch depth of water on 140 acres in one rotation.

During the growing season, each well is pumped intermittently, depending
on the soil moisture available for the crops. During dry spells, however, more
than half the wells are pumped simultaneously.

Water-level Fluctuations

Development of ground water was gradual until 1968, when development
increased rapidly. Development rate since 1968 has had a pronounced effect on
water levels. Until 1968, for example, the levels in Floridan aquifer wells 9, 22,
75, and 134 (location on fig. 1) fluctuated chiefly in response to above- or
below-normal rainfall as shown in figures 12 and 13. After 1968, response to
local irrigation pumpage overshadowed the response to rainfall.

Figure 13 is a hydrograph of well 22 which illustrates the water-level
changes that occurred from 1948 through 1968. Periods of high-water levels
(caused by above-normal rainfall) were averaged with periods of low-water levels
(caused by below-normal rainfall) and a trend line or rate of decline was
developed on the hydrograph. This trend line indicates that from 1948 to 1968
the water level declined 0.25 foot per year on the average; a similar trend is also
evident on the hydrograph in figure 12. This long-term decline was probably
caused by increased ground-water use in southern Walton County.








I 45
MISSING RECORD ...' "" "- -
WELL 134
12 Depth 509ft. 0

S-150 5
121 ----I-I- 153 I

S20 0 Sr3
o-




SWELL 75 10
I0 Depth 160ft.

a 51111ii




MISSING RECORD I
15 -


I0 Depth 4966f, 1ft.




0 0
1DEFUNIAK SPRINGS 6 O 3



vJ J J J O J 0J J D J J 0J. J DJ J DJ J DJ S
1961 19M2 1963 1964 195 l9 1967 196B 199 1970
















*z.pnbe
UIPDid aip Onu imp aIPA& uIq PAMj =W&M Bumoi qduzfozpAH *E1 SoIs


"40


30




o o
20







0


SI I I I I I I I I I I I I I I I I I I I ~ I
WELL 22
Dspht 450ft

EnSIATED TREND LINE






DISCOWN)ED,
WILL CAVED


I I I I I I I3 I I N I I I I I II I wI I a 1
1647 46 46 1660 II ri 13 4 allb i S1 a 3r I 61 56 160 a 2 6 64 1645 66 67 66 6


w

20~

10i


0I






REPORT OF INVESTIGATION NO. 27


In 1968, water levels declined sharply from January through April 1968-a
decline (figs. 12 and 13) caused by a lack of recharge to the aquifer brought
about by a severe drought. From May through July 1968 water levels declined
even faster, showing the added effect of pumping for irrigation in southern
Walton County.

Pumping for irrigation at the Owl's Head Farm during the spring and
summer of 1969 and 1970 (fig. 14), caused a sharp decline in levels in
observation wells 91 and 99 which are about 8 miles apart (fig. 1). Because the
wells are not pumped, their fluctuation in level represents the effect of pumping
from nearby wells. Pumping for irrigation stopped in July 1969 and by mid-May
1970 recovery of levels was virtually complete.

The amount of water-level decline varies directly with pumping which in
turn varies with weather conditions and with the water requirements of the
different types of crops planted. Soybeans and sorghum generally require less
water than corn. The maximum observed decline in water level-about 80 feet at
well 99-resulted from heavy pumping to irrigate corn during the unusually dry
weather of June 1969. At well 91 pumping was less intensive because the area
was planted in soybeans and sorghum. Hence, its low-water level of June 1969
was not outstanding.

In 1970 ground-water levels were low in the summer and again in the early
fall. The fall decline resulted from pumping for an early crop of corn and a later
crop of soybeans.

By June 1970, after 60 wells had been pumped intermittently at
800-1,000 gpm during April-June, water levels had declined more than 80 feet at
the Owl's Head Farm north of Freeport (fig. 15); limited pumping of 6 wells at
the Mossy Head Farm caused levels there to decline about 10 feet. The effects of
pumping extended outward more than 10 miles from the center of pumping at
the Owl's Head Farm (fig. 9). The extensive decline in levels from March 1970 to
June 1970 temporarily changed the direction of ground-water movement. A
comparison of figure 8 with figure 9 will show in detail the nature of this change
in direction. Ground water that moved toward Choctawhatchee River, Chocta-
whatchee Bay, and the gulf generally was captured in the areas of heavy
withdrawals. The lowering of the head in the Floridan aquifer caused an increase
in head difference between the Floridan and the sand-and-gravel aquifers and,
consequently, recharge was increased.

Aquifer Characteristics

Transmissivity is a measure of the ability of an aquifer to transmit water.





BUREAU OF GEOLOGY


20


0


-20





40


20


0


-20


-40


/^\^


SWELL 91 1
Depth 506 ft.

I 1111111111111111111111 111 I1








- -





WELL 99
Depth 440 ft.


JA SO N DJ M AM J J A S ON DIJ F MA M J J A S O ND
1968 1969 1970


sO


100


120
U.
140 w


-J

110




150



170 9


190


FIgue 14. Hydroraphs showing water levels in wells that tap the Flortdan
aquifer at Owl's Head Parm.

It represents the rate at which water is transmitted through a unit width of the
aquifer under a unit hydraulic gradient. In this report transmissivity is given in
units of gallons per day per foot.

In Walton County, the transmissivity is highly variable ranging from 4,000
gpd/ft (gallons per day per foot) along the central and eastern gulf coast to
100,000 gpd/ft along the western gulf coast as shown in figure 16. Trans-
missivity is 180,000 gpd/ft at a point 10 miles south of DeFuniak Springs and as
low as 24,000 gpd/ft to the northwest, near Argyle. In general, transmissivity is
relatively high in the southcentral part of the county.







REPORT OF INVESTIGATION NO. 76


IT W


,4
MNMIn Is NET DCLIUN OF
POTENTIOMETIIC SURFACE IN FEET.


LINE OF EQUAL DECLINE. INTENVlL
10 FEET.


S ; 'I MILE

0 5 10 i KLCIE 6R*


Fire 15. Map of the net decline of potentlometric surface of the Plaridan
aquifer from March 9-13 to June 22-26,1970.


R21W


AiOW hig w





BUREAU OF GEOLOGY


Variation in transmissivity is the result of local differences in the
composition of the aquifer and its thickness. Along the gulf coast much limey
clay and marl are interbedded with the limestone of the aquifer; and in northern
Walton County, large amounts of clay and sand occur throughout the aquifer,
especially in the upper section. The presence of these materials accounts for its
lower transmissibility in those places.

The storage coefficient is the volume of water an aquifer releases from or
takes into storage per unit surface area of the aquifer per unit change in head. In
Walton County storage coefficient ranges from 1.6 x 10T4 to 5.6 x 10-4 (fig. 16).

Quality of Water

Water from wells tapping the Floridan aquifer is of acceptable chemical
quality except in an area in southeastern Walton County adjacent to Chocta-
whatchee Bay, where the water is highly mineralized. Table 1 lists chemical
analysis of water from selected Floridan aquifer wells that range in depth from
80 to 506 feet.

Water from Floridan wells north of Choctawhatchee Bay is of calcium
bicarbonate type and is low in dissolved solids. The low dissolved solids reflects
the quality of recharge from the sand-and-gravel aquifer. Water from Floridan
wells adjacent to Choctawhatchee Bay is of sodium chloride type and is high in
dissolved solids, reflecting the quality of water that occurs at depth within the
Floridan aquifer.

Dissolved-solids concentration in water from the Floridan aquifer ranges
from less than 70 to 3,500 mg/l (fig. 17); and chloride concentration is as much
as 2,000 mg/l (fig. 18). Water from Floridan wells north of Choctawhatchee Bay
usually contains less than 5 and 150 mg/1 of chloride and dissolved solids,
respectively. Adjacent to Choctawhatchee Bay, however, both chloride and
dissolved solids increase with depth in most wells. The chloride concentration of
water from Floridan wells adjacent to the bay is shown in figure 18.

In area A of figure 18, water from the Floridan ranges in chloride
concentration from 61 to 790 mg/l; bottom elevation of wells range from 206 to
470 feet below sea level. Chloride is highest in water from wells along the south
side of the bay increasingly westwardly from Tucker Bayou to Hogtown Bayou.

In area B, water from the Floridan ranges in chloride concentration from
10 to 600 mg/l; bottom elevations of wells range from 80 to 533 feet below sea
level though most are below 350 feet. The safe useful well depth in area B is
about 500 feet below sea level. Wells with bottom elevations more than 500 feet
below sea level usually contain water with chloride greater than 250 mg/l.









A 21


REPORT OF INVESTIGATION NO. 76

nm ,'R20W RI9W RIBW


I I 610 ,


R17 W


30*1 '-


? O 110 MILES
C s to 0 s KLUMsV0


Figure 16. Map showing tranmin tles and
that tap the Floridan aquifer.


storage coefficients at wel























TABLE I
QUALITY OF FLORIDAN AQUIFER WELLS IN WALTON COUNTY
(Cwhmical alysue millipram pw Ur)



coducl-
D N anc Disdlvd MaY Te-
WeB da (micra sads Che Tot Fluo Cia- me- Ni- Alkalin- ai- per
siu mber dept codc- nabm (cak- ride roa ride Hdmun ciam slum Sodium tra ily (a boeale ma
as l I Wd member* (Wel) ton at 25C0 bled) (CI) pH (Fe) (F) (Ca-Mg) (Ca) (Mg) (Na) (NO)) (CCODI) (HCO,) (C

13 30205N0861432.1 340 06-19-68 276 172 16 76 0.2 132 41 6.7 6.2 0.1 125 152 235
18 302112N061501.1 455 0540770 2.200 100 564 7.9 0.02 .6 280 49 37 311 .0 157 191 21.0
38 302243N0160917.1 389 05-5-70 1350 771 362 8.1 .02 .6 139 26 18 250 0 98 120 20.0
47 302346N0861812.1 400 09-25-69 330 176 47 8.1 0 .7 123 21 17 23 120 20.0
50 302444N0860010.1 229 09-2469 ISO 71 7.0 7.9 0 .3 68 IS 7.3 5.7 66 80 22.0
52 302549N0860717.1 240 09-2549 2300 1220 0 8.1 .01 .8 171 32 22 400 131 160 22.0
91 303214N0855804.1 506 06-12-70 174 102 2.2 7.5 .01 .2 83 19 86 2.7 .0 70 96 23.8
99 303426N0NO0611.1 440 06-12-70 160 91 1.2 8.1 0 .2 83 19 8. 2.1 .0 75 92 23.
151 305043N0860833.1 320 0504-70 225 136 2.0 7.9 0 .2 113 27 II 1.8 .0 108 132 21.0
161 305732N0860208.1 120 05-04-70 192 III 1. 7. 0 .2 96 34 2.5 16 .5 94 115 20.5
163 305816N0860815.1 80 05-04-70 232 143 4.0 8.0 0.2 .2 121 40 5.0 2A 6.8 III 135 19.0


WM 11luibr b nldedf ad eloltder of e wll site. EAmpl: t8 13 b at Lat. 305P0Ji"N, L eal. 061432"w, d there b I mO.






REPORT OF INVESTIGATION NO. 76


Generally, wells with bottom elevations less than 400 feet below sea level
contain water low in chloride. Several relatively shallow wells in area B yield
water of excellent chemical quality; they tap a little used part of the Floridan
aquifer along the coast that lies less than 100 feet below land surface and that
varies in thickness from 90 to 100 feet (figs. 5, 6, and 7).

In area C, water from wells tapping the Floridan ranges in chloride content
from 10 to 32 mg/l; bottom elevations of wells range from 397 to 496 feet
below mean sea level.

In area D, water from the Floridan ranges in chloride content from 422 to
2,040 mg/l; bottom elevations of wells range from 172 to 303 feet below sea
level. Chloride content increases with well depth. This was substantiated by
samples from well 60 (fig. 1), northeast of Jolly Bayou. The well, bottom
elevation 303 feet below sea level, contained 106 feet of 4-inch casing and
flowed about 25 gpm for 45 minutes before sampling was begun. Water samples
were field analyzed for temperature, pH, specific conductance, and chloride. The
results are as follows:

Specific
Sampling Depth Temperature Conductance Chloride
(feet below msl) (C) pH (micromhos at 2S5C) (mg/1)
130 22.0 7.9 6,100 2,040
200 22.0 7.8 7,000 2,480
280 22.5 7.5 8,600 3,000
303 22.0 7.7 11,000 4,200

Water from this well contained the most chloride of any well sampled. The high
chloride content of water from the Floridan in area D may be the result of
upward movement of salt water from depth. Salt-water encroachment of the
aquifer from the bay or gulf is not possible because the potentiometric surface is
above sea level (fig. 8).

Electric logs indicate that saline water (dissolved solids in excess of 1,000
mg/l) occurs in the Floridan aquifer throughout Walton County. The fresh-
water-saline-water interface is about 750 feet below sea level near Bruce in the
southeastern part of the county, about 1,200 feet below near Miramar Beach in
the southwestern part, about 650 feet below near Glendale in the northeastern
part, and about 950 feet below near Paxton in the northwestern part. For the
most part, fresh and salt water are not in direct contact but are separated by a
"zone of diffusion," an area where mixing takes place. In southwestern Walton
County, the Floridan aquifer contains a wedge of cay which thins eastward and
gradually pinches out about 8 miles east of the Okaloosa County line (Marsh, p.
45, 1966). The top of the clay is about 650 feet below sea level-it prevents






BUREAU OF GEOLOGY


N20W
r**i


NR1IW NIlW
sllnn'


SI?7W


I a I-


O I IF IpMILII
I 0 I I KIL4sTmRS


Plnps 17. Mp showing diiolved sodld in
Flordan aquifer.


water from wells that tap the


S21 w








REPORT OF INVESTIGATION NO. 76


R21W e6s, R20W
aB.I5*


AO9W RISW
6006'


R 17 W


I II I'


s30'IS--


10 MILES

10 5 I o IS KILMETERS


Pigure 18. Map showing chloride content of
Floridan aquifer.


water from wells that tap the


31sqo0
T6N












T4N






41
T3N






T2N






TIN





30
TIS







72S





BUREAU OF GEOLOGY


upward movement of the underlying salt water and accounts for the low
dissolved solids and chloride concentrations in water from wells in area C (fig.
18).

The configuration of the potentiometric surface of the Floridan aquifer in
the vicinity of Choctawhatchee Bay and above the mouth of the Chocta-
whatchee River (fig. 8) and its position above the water surface (fig. 7) indicate
that the Floridan aquifer leaks to the bay and river. In area D (fig. 18) this
leakage may consist of salt water moving up through permeable faulted zones,
possibly mixed with fresh water in the upper part of the aquifer and now
evidenced by the poor quality of the ground water in the area.

The chloride concentration of water from wells in the Floridan aquifer has
not changed appreciably during the last 10 years. Graphs in figure 19 show that
chloride varies but with no specific upward trend in water from coastal area
wells. The potential for salt-water contamination does exist, however, in the
coastal area. Increasing ground-water withdrawals with attendant declining water
levels could cause an upward and landward displacement of fresh ground water
with salty water.

SURFACE WATER

OCCURRENCE OF STREAMFLOW

Streamflow, water flowing overland in natural channels, is derived from
rainfall, from lakes or swamps, and from ground-water runoff. Ground-water
runoff constitutes the base flow of a stream and sustains streamflow during
periods of drought. In Walton County, the base flow of most streams comes
entirely from the sand-and-gravel aquifer.

STREAMS

Streamflow originating in Walton County averages about 1,600 cfs (cubic
feet per second) or 1.0 bgd (billion gallons per day); this is based on discharge
from gaged areas and estimates of ungaged areas. Estimated discharges were
obtained by correlation with known yields from similar drainage basins.

Table 2 shows that streams of Walton County have high yields (rate of
discharge per square mile of drainage area). Shoal River, Alaqua Creek, and
Magnolia Creek discharge, on the average, 1.85, 2.38, and 3.24 cfsm (cubic feet
per second per square mile), respectively. The highest yields are from drainage
basins in the southern part of the county.









Ayunmoo uO)IM Ul RfPM
lzsjnbE ipuold uioq s.)Bm jo j)uauoo W PPIop SuLoqI S L[BD IT61 oz tldj

600 I I I I I
No i I
r-C
S500 WELL 48
S i Depth 337 ft.
z
o0 w
0. 400
C WELL 9
SDepth 466 ft.
a 300 -


0 220oo 200I I----" .
E.l -
g 0

9 0 WELL 75
Depth 106ft _..---- ------ ---------
I I I I I I I I I


1962 1963 1964 1965 1966 1967 1968 1969 1970


1961











TABLE 2
SUMMARY OF STREAMFLOW DATA AT GAGING SITES IN WALTON COUNTY


Miminum flow for
Avenge flow period of record
Site
number Drainag Period Year Esimated,
on are of of Recorded 1931-70
ue 1 Gaging Station (sq. m.) Record Record (cfs) (ctm) (cf) (cfs) Date

166 Eightmile Creek near Gaskin 24.9 1968-70 2 34.5 1.39 6.24 10-24-68
169 Sandy Creek near Argyle 51.8 1968-70 2 55.7* 1.08 5.07 10-24-68
170 Bruce Creek near Redbay 51.4 1968-70 2 106 e 2.06 5.10 10-24-68
173 Seven Runs Creek near Redbay 2.58 1968-70 2 85.6 332 96.0 26 10-23-68
174 Choctawhatchee River near Bruced 4,384 1930-70 40 6,830 1.6 6,830 1,290 10-27-68
177 Magnolia Creek near Freeportd 11.2 1968-70 2 363 3.24 44.0 19 10-23-68
180 Alaqua Creek near DeFuniak Springd 65.6 1951-70 19 156 2.38 170 27 1955"
185 Shoal River near Mossy Headd 123 1951-70 19 227 1.85 230 42 06-09-56

Day discharge station
Estimated
*June 9, 21, 22, 30, and July 1






REPORT OF INVESTIGATION NO. 76


The base flow of most streams in the county is high.. Base flow can be
estimated from stream-discharge hydrographs by separating the base flow from
that part of the storm or overland runoff that causes the sharp increase (flood
peaks) in stream discharge. An approximation of base flow can be made
graphically by drawing a smooth curve on the hydrograph tangent to the low
points at each end of the flood peaks. For example, an analysis of the
hydrographs in figure 20 indicates that during March, April, and May 1970, a
period of normal rainfall, the base flow from Shoal River, Alaqua Creek, and
Magnolia Creek averaged 75, 80, and 90 percent of the total flow, respectively.
The effect of subsurface return flow of irrigation water may account for the
higher base flow of Magnolia Creek.

The minimum flows measured during 1968-70 (table 2) resulted from a
severe drought that ended about November 1968. Although 2 years is too brief a
time in which to establish the limits of extreme hydrologic events, analysis of
long-term records for streams in or near Walton County showed that the
minimum streamflows measured during 1968 were representative of the
minimum flows likely to occur over a much longer time. At Shoal River near
Mossy Head, for example, the minimum for 1968-70 was 46 cfs, compared to
the 42-cfs minimum of record since 1951. At Choctawhatchee River near Bruce,
the 1,290-cfs minimum for 1968-70 was the lowest discharge since 1930. At
Alaqua Creek near DeFuniak Springs, a 46-cfs minimum for October 1968 was
the fifth lowest discharge since the 1955 record low of 27 cfs; the streamflow
records for this station began in April 1951.

Flow-duration curves for Shoal and Choctawhatchee Rivers and Alaqua,
Magnolia, and Seven Runs Creeks are similar-their relatively flat slopes,
particularly at the lower end, indicate that these basins have large ground-water
storage (fig. 21). The relatively flat slope at the upper end of the flow-duration
curve for Choctawhatchee River suggests that stream has large flood-plain
storage. Seven Runs Creek has the highest yield per square mile and
Choctawhachee River the lowest.

Information on the recurrence of low flows is particularly important in
designing surface-water supply systems because the lowest discharge usually
establishes the limits of supply without storage. Low flow frequency curves for
\laqua Creek, Shaol River, and Choctawhatchee River are shown in figures
!2-24. Based on minimum 7-day flows for 10-year recurrence intervals
commonly used as a basis for design of water-supply systems), and assuming
hat flow conditions in the future will be comparable to those experienced
luring the period of record, 35 48 and 1,550 cfs are the minimum quantities of
vater available from Alaqua Creek, Shoal River, and Choctawhatchee River,
respectively.





BUREAU OF GEOLOGY


900

700

500

300

100


800

600

400

200
tOO
100


300

100


MAGNOLIA CREEK NEAR FREEPORT
ESTIMATED BASE FLOW Drainoge Area 11.2 sq. mi.

MARCH APRIL MAY
MARCH APRIL MAY


Figure 20. Hydrographs showing daily flow of three streams in Walton
County, March-May 1970.

Measurements of 22 of Walton County streams on May 14-26, during a
period of low flow suggest the streams may be perennial (fig. 25). The flows
were about the same in May 1969 as in May 1970.

Industrial or residential encroachment onto the flood plain of the county
has been slight and, therefore, flood damage has been minimal. Stream flood
plains in the county are generally flat swampy areas inundated to some degree
almost every year. During a record flood of 1953 at Alaqua Creek near
DeFuniak Springs (fig. 1) when the peak discharge was 5,160 cfs, the stage was
about 5 feet above bank-full stage (38.1 feet above sea level) and the creek
inundated more than a one-quarter-mile-wide section of flood plain at the gage
site. Two days after the flood peak, the stage receded and the creek was within
its banks. In 1964, Shoal River near Mossy Head (fig. 1) reached a record-peak
discharge of 10,500 cfs at an elevation of 129.2 feet above sea level. Peak stage







REPORT OF INVESTIGATION NO. 76


0.5
0.4


I 5 10


90 95 99


999


PERCENTAGE OF TIME INDICATED DISCHARGE WAS EQUALED OR EXCEEDED


Figure 21. Flow-duration curves for major streams in Walton County.




was about 10 feet above bank-full stage and the river inundated a section of
flood plain at the gage site more than a half mile wide. Two days after the flood
peak, the stage receded. The Alaqua Creek flood described above had a
recurrence interval greater than 20 years; the Shoal River flood, greater than 50
years.


Regionalized flood-frequency curves shown in figure 26 apply to Shoal
River and its tributaries, to tributaries of Choctawhatchee River, and to streams
draining south into Choctawhatchee Bay. These flood-frequency curves may be
used at ungaged streams to estimate the probable magnitude of floods having
recurrence intervals of 2.33 (mean annual), 5, 10, 20, and 50 years. A stream
with a drainage area of 50 square miles, for example, experiencing a flood having
a recurrence interval of 10 years, will have a discharge of 3,400 cfs.


SEVEN RUNS CREEK, 1969-70, Adjusted to 1931-70.
Drainage Areao 258 sq. mi.


, 1969-70 Adjusted to 1931-70.
sq. mi.


CHOCTAWHATCHEE RIVER,
1931-70. Droinage Area 4,384 sq mI.





S SHOAL RIVER, 1952-70, Adjusted to 1931-70.
Droinoge Areoa 123 sq. ml.



FOR COMPARISON DISCHARGES ARE IN CFSM AND
ADJUSTED FOR DIFFERENCES IN TIME SPAN OF RECORD.




S I I I ..I I I,


0.01


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unbsW Pi o ao j Aaw o u~nbhn pa 9praftuw 8iwquo qidu)


I I I I I a


200



100



50
40

30

20



10


I I I .' '. I


I I I I. I


1.5 2 3 4 5


RECURRENCE INTERVAL YEARS


I I


I I


0
C, :




0
I
i

B

SP


, 1 .1 I 1 ... I


_ _____ ____


20 30 40


z
0
2 0


a

w
U.

0.5
0.4 u

0.3


0


30 DAYS
7 DAYS
I DAY
















poqIg as PoO Aoi o onuenba


OL-S6Tm 'PH AoSN nE u a.d
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1.5 2 3 4 5


RECURRENCE INTERVAL YEARS


20 30 40


0r;
z




0

I
0


0


'ET OSiJd


300

200



100



50
40

30

20


TT

-






. 30-DAYS
7-DAYS
I-DAY






I I


2
z
0


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-----~ ~














cc 10A000 | i | I I | I | I


LJ 5000 -
4000 -
S3000 30-DAYS
3000 0.5
2000 I-DAY and
7-DAYS
C ooo I I I I I I I I I I oas -
S1000 2iiI
1.01 U 15 2 3 4 5 10 20 30 40 50

RECURRENCE INTERVAL ,YEARS

tpre 24. GOaph dowgi mapitm Mad dfequeacy of low flow at
Choctawhatchee River ne Brace, 1931-70.










R 21W


REPORT OF INVESTIGATION NO. 76


,l R20W RI9W RIW R 17 W
fifi151 a.CM'


0 10 MILES
0 I 0 IS I I T


Figure 25. Map showing stream dishg an dsslved soids May 14-26,
1970.


1 I W


BU -
TIS


30s13'-






BUREAU OF GEOLOGY


50q000











0
en
5000








I
I.-



Cu

O 1000

Cr

500


10 50 100


500 1000 2000


DRAINAGE AREA ,SQUARE MILES

Figure 26. Gkaph showing regionalized flood-frequency curves for Shoal
River Basin and basins between Choctawhachee River and
Yellow River.

LAKES


Walton County has about 25 named lakes; they range in size from 10 to
400 acres. Most of them are primarily recreational. Fifteen of the lakes are near
the coast and are brackish most of the time; the others are fresh-water lakes in
the northern part of the county. Lake Jackson is the largest lake in the county,
with a surface area of about 400 acres. DeFuniak Lake, measuring 40 acres, is
one of the smaller.





REPORT OF INVESTIGATION NO. 76


Lake Jackson, in common with most lakes and ponds in northern Walton
County, was formed by solution and eventual collapse of the underlying
limestone to form a sink. It is a water-table lake fed by the sand-and-gravel
aquifer, by rainfall, and by a small amount of surface runoff. The level of the
lake rises when it rains, partly because of rainfall on the lake and partly from
increased inflow from the sand-and-gravel aquifer. Depressions detected in the
lake bottom by a fathometer indicate that a hydraulic connection probably
exists between the lake and the Floridan aquifer. The level of the lake generally
stands from 30 to 35 feet above the potentiometric surface of the Floridan
aquifer and the lake most likely loses some water to the Floridan aquifer. At
high stages, Lake Jackson overflows through a culvert into a tributary of Pond
Creek. The almost steady decline in lake level from January to November 1968
reflects a drought. The level declined sharply in June 1970 after the culvert
outlet (fig. 27) was cleaned.

Chemical analyses shown in table 3 indicate that Lake Jackson and
DeFuniak Lake contain water of excellent chemical quality. The water contains
dissolved solids less than 20 mg/1 and is similar to the quality of rainwater.

QUALITY OF WATER

Walton County has an abundant supply of surface water whose chemical
quality is acceptable for most uses. Dissolved-solids concentration of stream
water ranged from 10 to 125 mg/1, chloride from 2.0 to 10 mg/1 (fig. 25, table
3). A large percentage of the total flow of most streams in the county is base
flow from the sand-and-gravel aquifer and, because of the relatively insoluble
nature of the aquifer, is low in dissolved solids. During peak flow, the major
difference in water quality is an increase in color and turbidity. The base flow of
a few streams such as Eightmile Creek, Spring Branch, Limestone Creek, and
Choctawhatchee River, is from the Floridan aquifer. During low flow, water in
these streams is high in dissolved solids primarily because of the calcium and
carbonate dissolved from the limestone as the ground water passes through that
aquifer.

The color and turbidity of the water of Walton County is objectionable
but not injurious. Most of the color comes from leaching of organic material in
the soil and turbidity is the result of the collodial suspension of sediment and
other nonsettleable particles in the water. Drinking Water Standards proposed by
the U.S. Public Health Service (1962) suggest that domestic water not exceed 15
color units or 5 turbidity units-water from streams in Walton County varies
from 5 to 50 platinum-cobalt color units and from 3.1 to 25 Jackson turbidity
units.











TAIIJ 3
QUAUTY OF WATER IN WALTON COUNTY IlSTAMS

Cemmkil uamy, mailiam per Uln



h' I b j j J J i}j I
-"- .. i i I !L j i i'j .,r


EightIllOe k 166 0514-0 12.3 90 6.8 22 30 10 6.0 12 2.0 1.7 0.3 37 0.0 0.3 33, 0.1 0.4 0.02 0.10 30 38 1 44 0.03 0.28 0.01
Spria Branh 167 05.19-70 19.5 195 7.8 2 5 4.6 74 35 3.1' 1,4 0.3 118 .0 .8 2.5 .1 .2 02 .09 97 101 4 109 S.0 .04 .001
ULmntaem wO k 168 05.19.70 13.0 190 7.9 21 5 10 74 35 3.1 2.0 .3 11 .0 .1 2.0 .1 .4 ,02 .10 94 101 7 125 7.0 JI .2 .01
Sandy reek 169 05.14-70 39.1 22 6.3 22 40 7.4 3.3 0.9 0.4 2.4 J 5 .0 .3 3.5 .1 .6 .37 .51 4.0 4.0 0 15 08 .0 .01
Irauc~mCk 170 05-2070 3.8 58 5.5 21 50 20 5.0 2.5 .9 4.4 2.1 I .0 .8 5.7 .1 1.0 1.90 2.30 1.0 10 9 25 4.9 4.90 1.20 .10
DeFunlakLake 171 05-2070 27 6.7 27 5 3J 05 2.2 .4 1.6 0.9 7 .0 1.9 2.8 .0 0.0 0.01 0.08 6.0 7.0 2 14 7.0 0.07 042 00
IBrmeCvek 172 05-14-70 20.2 23 5.9 21 30 9.4 4.2 1.1 .4 2.2 .6 3 .0 0.6 3.4 .1 .9 .15 ,25 2.0 4.0 2 15 .80 .36 .10
Sen RuansC~ k 173 05-14-70 53.2 70 4.7 25 5 6.9 3.2 2.7 1.8 2.9 34 0 .0 .4 9.3 .0 13.0 .00 .08 0.0 12 14 59 .11 .28 .01
Cbhocwhatch eRim 174 05.26-70 2.400 143 7.2 26 5 25 7.6 21 2.8 4.9 0.7 72 ,0 .6 6.3 .2 1.2 .03 .09 59 64 S 80 6.3 .11 .16 .02
BlackrOak 175 05.1.70 I 1.5 17 6.5 20 40 6.4 39 1.0 0.3 1.4 .2 2 .0 .6 2. ,1 0.0 .02 .06 2.0 4.0 2 II 7.9 .32 .22 .01
hitelrah 176 05-26.70 1.68 42 62 26 5 4.9 3.8 25 1,2 2.1 1.5 3 .3 5.8 .1 .7 .00 .02 2.0 II 9. 20 6.5 0 .22 .01
MalPie eLCaLk 177 05.14-70 30.0 90 4.7 20 5 5.8 3.4 3.5 2.6 2.0 4.2 0 0.0 .2 10.0 ,1 19.0 .00 .08 0.0 19 19 58 .58 .60 .01
Lafayelteca 2 178 05.1.70 112 60 5.4 26 5 3.4 3.0 24 1,8 1.9 2.9 1 .0 .6 3.1 .0 11.0 .00 .06 1.0 14 13 32 6.6 .04 .30 .01
IouimileC~ek 179 05-2070 21.2 19 5.6 21 20 4.3 3J 0.6 0.4 1.4 0.3 1 .0 .2 3.0 ,0 IJ .01 .05 1.0 3.0 2 II 7.0 .05 .16 .01
Alaqua Otk 10D 05-25-70 74.0 12 6.2 22 10 10 3.7 .6 .3 1.2 .2 3 .0 .0 2.0 .1 0.2 .02 .10 2.0 3.0 0 10 75 .01 1.10 .01
amin OCk 181 05-20.70 58.9 19 55 21 30 4.0 3.2 1.1 .4 1.9 .2 2 .0 .8 3.2 .0 .1 .00 .02 2.0 4.0 3 12 6.8 .05 0.16 .01
Rocky Cek 182 05-14-70 180 13 62 21 10 3.1 3.8 0.4 .2 1.5 .3 2 .0 .2 2.7 .1 .2 .00 .06 2.0 2.0 1 10 .01 .10 .01
Caney OCk 183 05-19-70 1.67 16 6.2 20 40 6.9 .5 .9 J 2.1 .2 2 .0 .6 3.4 ,0 .3 .05 .12 2.0 3.0 2 14 5.0 .05 .23 .01
GumCrak 184 05-20-70 .38 16 5.8 19 40 6.6 4.8 S .3 1.7 .2 2 .0 .6 3.1 .0 .4 .04 .10 2.0 2.0 1 13 6. .07 .24 .01
SholRiver 15 05-2$-70 1.9 16 6.2 24 10 6.1 3.6 .6 .4 1.4 .3 2 .0 .4 2.7 .1 .7 .02 .08 2.0 3.0 2 11 7.6 .07 .17 .01
Lake Jackso 186 05-13-70 32 6.2 27 5 10 0. 1.8 .6 2J .9 4 .0 4,6 3.6 .1 .0 .03 .06 3.0 7.0 4 16 .01 JS .01
Pine LopCek 187 05-19-70 9.65 34 7.1 22 20 6.4 6.2 3.2 1.3 1.6 .2 14 .0 0.8 2.5 .1 .2 .03 .08 II 14 2 23 7.5 .02 24 .01
LoaCCtOk 188 05-19-70 14.3 16 6.4 21 20 63 5.0 0.9 0.4 1.3 .3 3 .0 .5 31.0 .5 .02 .08 2.0 3.0 1 13 6.5 .05 .20 .01
Titrla k 189 05-12970 22.0 13 6J 20 10 7.6 3.3 .9 .3 1.1 .2 2 .0 .6 2.2 .0 .3 .02 .07 2.0 3.0 2 10 7. .05 .15 .01





REPORT OF INVESTIGATION NO. 76


WATER LEVEL,
MEAN SEA


FEET ABOVE
LEVEL


The water in Magnolia and Seven Runs Creeks increased in specific
conductance (a value directly related to dissolved solids content of water)
between October. 1968 and May 1970 because of increased concentrations of
potassium, nitrate, and chloride. Bicarbonate and pH (hydrogen-ion concentra-
tion) decreased; this is shown in the following tabulation:


I I I








BUREAU OF GEOLOGY


Specific
Discharge K NO3 C- HCO3 Conductance pH
(micromhos
Stream Date (cfs) (rg/l) at 250C)

Magnolia
Creek 10/23/68 22.2 1.0 1.2 5.0 3 25 5.7
05/14/70 30.0 4.2 19 10 0 90 4.7

Seven Runs
Creek 10/23/68 24.8 0.0 0 4.0 5 20 5.6
05/14/70 53.2 3.6 13 9.3 0 70 4.7


Ninety-five and 75 percent of their drainage basins, respectively, are farm land
treated with fertilizers and irrigated with water from the Floridan aquifer.
Fertilizer constituents generally applied are nitrogen, phosphoric acid, and
potash in ratios of 5, 10 and 15 percent, respectively. The application rate
ranges from 600 to 800 pounds per acre per crop per year. Nitrogen solutions
are also applied as a side dressing at a rate of 200 pounds per acre per crop per
year.

The pH, and bicarbonate concentration, of irrigation water from the
Floridan aquifer range from 7.8 to 8.1 and 90 to 100 mg/l, respectively; and
from the sand-and-gravel aquifer and streams they range from 5.5 to 6.0 and 1 to
5 mg/l, respectively. Most fertilizers are acid-forming (Volk, p. 14) and when
added to the soil apparently act as proton (H+) donors which react with the
Floridan aquifer irrigation water and the sand-and-gravel aquifer water to lower
the pH and eliminate bicarbonate from Magnolia and Seven Runs Creeks water
by the reactions:

H+ + HCO3= H2 C03

H2 C03 = H2 0+ C02

Specific conductance of water in Magnolia and Seven Runs Creeks
increased as discharge approached base flow conditions (fig. 28). Most fertilizer
constituents and irrigation water, therefore, reached these streams by infiltration
to the water table and lateral movement through the sand-and-gravel aquifer.
Bruce and Sandy Creeks also receive base flow from the sand-and-gravel aquifer
but specific conductance did not change during the same period-their drainage
basins are agrculturally undeveloped.






REPORT OF INVESTIGATION NO. 76


SPECIFIC CONDUCTANCE MICROMHOS AT 250 C

N- .o .( l ) -4 D W
0 0 0 0 0 0 0 0 0 0


0







0
_n

0






0C
Z


31.
0
c-


SAMPLING DISCHARGE
PERCENT OF AVERAGE


3 r




Iro


Figure 28. Graph showing variation in specific conductance of selected
streams and discharge of Magnolia and Seven Runs Creeks.

To develop background information regarding the possible existence of
stream pollution in the county, streams were sampled for nutrients-nitrogen
(ammonia, nitrite, nitrate, and organic), and phosphate (ortho- and total). Water
receiving raw or treated sewage, or agricultural drainage, normally contains
appreciable concentrations of nutrients. Except Bruce Creek most streams
tested have concentrations of nitrogen and phosphate below 0.50 mg/l (table 3).
The higher concentrations of nutriefits of Bruce Creek indicate some pollution
upstream from the sampling site.


i


\I
\ \











i/
I !











Sl
''



M 0CO0
S^S^~n


3,3,
5iSgi
U> Mm
I I I


I I I I I














\ C
\ \













'0
M







W 0^
(ON fyi
IIfj II I i












TABLE 4
DIFFERENCES IN SIGNIFICANT CHARACTERISTICS OF SELECTED STREAMS
OCTOBER 1969-SEPTEMBER 1970


Site number Date of Discharg Specific conductance Temperature Dissolved Oxygen Collforms
Station Name on figure I collection (cf) (mlcmomhos at 25C) pH (C) mg/1 per 100 ml

Eghtmile Creek 166 10-15-69 17 59 6.5 19 6.5 1,800
09-28.70 119 26 5.6 22 5.6 5,400
Sandy Creek 169 10-15-69 37 19 5.3 18 8.2 3,400
09-28-70 153 21 4.8 22 7.3 8,800
Bruce Creek 172 10-15-69 44 25 5.3 19 8.0 2,000
09-28-70 49 22 5.5 23 7.2 750
Seven Runs Creek 173 10-15-69 72 60 4.7 20 7.8 1,650
09-28-70 88 62 4.5 24 7.6 4,400
Choctawhatchee River 174 10-1569 3,820 110 7.0 21 6.6 450
09.28-70 3,050 136 7.2 26 6.7 250
Magnolia Creek 177 10-1569 41 77 4.3 20 8.0 3,200
09.28-70 32 78 4.6 22 8.0 2,000
Fourmile Creek* 179 09.28.70 21 4.6 23 7.4 2,950
Alaqua Creek 180 10-15-69 105 13 5.6 18 8.0 4,600
09.28.70 208 18 5.6 22 7.5 4,600
Rocky Creek 182 10-15-69 95 15 5.2 18 8.2 2,000
09-28-70 173 13 4.9 22 7.4 1,850
Shoal River 185 10-1569 153 19 5.4 19 8.6 3,500
09-28-70 313 20 5.1 22 7.6 7,400






REPORT OF INVESTIGATION NO. 76


The presence of coliform bacteria in water can also be used as evidence of
pollution. Coliforms originate from excreta of warm-blooded animals and are
found in sewage, soils, and vegetation. The degree of pollution is indicated by
the number of coliforms present. For a surface-water supply to be acceptable the
Federal Water Pollution Control Administration suggests (1969) that coliforms
should not exceed 10,000 colonies per 100 ml (milliliters). With this limitation,
water-treatment plants are considered capable of producing water meeting
drinking water standards of 2.2 coliform colonies per 100 ml. Coliform tests of
10 streams in Walton County, shown in table 4, indicate that, at the time of
sampling, the streams all met the limitation described above.

In 1969 neither the water nor bottom sediments from Magnolia Creek
contained detectable amounts of pesticides but in 1970 the bottom sediments
contained DDD, DDE, and DDT (table 5). Pesticides accumulate and adsorb on
stream-bottom sediments. These pesticides could have reached Magnolia Creek
by direct surface runoff, by wind drift from adjacent treated areas, or through
ground-water discharge to the stream. Either separately or in combination, the
first two routes are the most likely because the pesticides would be adsorbed by
the soil and underlying sediments of the sand-and-gravel aquifer before reaching
Magnolia Creek.

WATER USE AND AVAILABILITY

Most of the water used in Walton County comes from the Floridan
aquifer. The sand-and-gravel aquifer supplies some small, mostly rural, domestic
uses. In 1970 13.2 mgd was withdrawn for all uses, of which 12.7 mgd was from
the Floridan.

Since 1968, more water has been withdrawn for irrigation than for all
other uses. Of the 13.2 mgd pumped during 1970, for example, 10 mgd (11,000
acre-feet) on the average was used for irrigation. Water withdrawn for industrial
use averaged about 1.5 mgd for the same period; and pumpage for DeFuniak
Springs, which has the largest municipal water supply in the county, averaged
only 0.6 mgd. The towns of Argyle, Freeport, Mirmar Beach, Paxton, and a few
other small communities had a combined average pumpage of about 0.1 mgd.
Water withdrawn for rural domestic use is estimated to be 1.0 mgd, half of
which is from the sand-and-gravel aquifer.

Surface water is used primarily for recreation. Choctawhatchee River and
Choctawhatchee Bay are the main water bodies and are used for boating, fishing,
and swimming. A few farm ponds are used to water livestock. Most streams in
the county are overlooked as potential sources of water supply even though they
have high base flows and the quality is acceptable for domestic use. For


















TABLE 5
PESTICIDE ANALYSES FOR WATER AND BOTTOM SEDIMENT FROM MAGNOLIA CREEK


Insecticides Herbicides

Site number Date of Discharge Temperature
on f1re I collection (cfs) (C) Aldrin DDD DDE DDT Dieldrin Endrin Heplachlor Undane 24-D 2,4,5- SUvex

Water Samples (pg/1)

177 0626-69 22.2 26 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
177 06-1870 38.6 24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Bottom Sediments (pg/kg)

177 06-26-69 22.2 26 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
177 06-18-70 38.6 24 0.0 0.2 1.0 0.9 0.0 0.0 0.0 0.0







REPORT OF INVESTIGATION NO. 76


example, Seven Runs and Magnolia Creeks have a combined average discharge
equivalent to 88,250 acre-feet per year-more than eight times greater than the
volume of ground water used for irrigation during 1970-and neither stream is
used for irrigation. Even during drought, streamflow originating in Walton
County is about 300 mgd-or more than 20 times greater than the quantity used
in 1970.

The quantity of ground water available for use from the Floridan aquifer is
substantial. For example, the Floridan aquifer contains an estimated 150,000
acre-feet of fresh water in Walton County. The volume of water withdrawn from
the aquifer during 1970 was less than 15,000 acre-feet. Wells tapping the aquifer
yield from 500 to 1,000 gpm except along the coast where yields are generally
less than 100 gpm.

Except from an area adjacent to Choctawhatchee River and Bay, ground
water is of acceptable chemical quality. Because along the coast, aquifer
transmissivity is low and saline water occurs at relatively shallow depths within
the aquifer, care and judgment are required in developing wells. With proper
planning and development, the coastal ground water may be utilized without
deleterious effects. For example, by using widely spaced, low capacity wells
(100 gpm or less) drawdowns likely will not be great enough to cause upward
migration of salt water in the aquifer.

Can the Floridan aquifer sustain a large seasonal irrigation pumpage in
southern Walton County without salt-water contamination of the aquifer?

In 1970 before pumping for irrigation began in the southeastern part of
the county, the potentiometric surface of the Floridan aquifer along the bay and
gulf ranged between 10 and 20 feet above sea level (fig. 8). As long as that
surface is above sea level, ground water will continue to discharge to the gulf and
to the bay where hydraulic continuity exists and thus prevent landward
movement of sea water into the aquifer. The amount of water that can be safely
pumped, therefore, is at most that volume that can be removed until the
potentiometric surface of the Floridan declines to sea level along the coast.

Ground-water pumpage for irrigation in southern Walton County during
that part of the April-June 1970 pumping season when pumping was most
intensive averaged about 20 mgd. Net decline in the potentiometric surface of
the Floridan aquifer south of Freeport averaged about 10 feet (fig. 14), bring it
to near sea level along the bay and gulf in June 1970. According to the Theis
nonequilibrium formula (Theis, 1935), pumping at a rate of 26 mgd over a
3-month period would lower the potentiometric surface to sea level or to the
point where salt-water encroachment could occur along the coast. Consequently,






BUREAU OF GEOLOGY


if ground-water withdrawals in the south part of Walton County are increased
much above those of 1970, the potentiometric surface of the Floridan aquifer
should be expected to go below sea level along the coast.

Although there is no evidence of saline water moving upward near Owl's
Head Farm, where the cone of depression is below sea level during periods of
heavy pumping (fig. 9), that possibility exists.

SUGGESTIONS FOR FURTHER STUDY

In view of the large withdrawal of water from the Floridan aquifer in
southern Walton County and the potential for salt-water movement into the
upper aquifer from the lower part of the aquifer and from the coast, continuing
the water resources monitoring program now in effect would be worthwhile.
This program includes: the collection of quality samples from observation wells
near the center of heavy pumpage and along the coast, for indications of
saline-water movement; the periodic measurement of water levels in selected
wells to detect changes in level; and the collection of discharge and water-quality
data at Magnolia Creek to determine the long-term effects of irrigation water on
the stream.

SUMMARY AND CONCLUSIONS

The two ground-water reservoirs of Walton County are the sand-and-gravel
aquifer and the Floridan aquifer. The former is thickest in westcentral Walton
County. It is important because it stores water, maintains streamflow and is a
source of recharge for the underlying Floridan aquifer in those parts of the
county where the water table is higher than the potentiometric surface of the
Floridan aquifer and where the confining bed is permeable, thin or breached.
Although water of the sand-and-gravel aquifer is low in dissolved solids, it is
acidic and therefore corrosive; it also contains high concentrations of iron which
may make it undesirable as a domestic or industrial water supply.

The Floridan aquifer underlies all of the county and is the principle source
of water supply. It is composed primarily of limestone ranging in age from lower
Miocene to upper Eocene. The aquifer varies in thickness from 700 to 1,000 feet
and is confined by clay and marl of varying thickness. The top of the aquifer
ranges from 50 feet below land surface in northeastern Walton County to 300
feet below in the midwestern part. The transmissivity ranges from 4,000 gpd/ft
along the coast to 180,000 gpd/ft in southeastern Walton County, the storage
coefficient ranges from 1.6 x 1T4 to 5.6 x 104.

In Walton County the Floridan aquifer is recharged by downward leakage







REPORT OF INVESTIGATION NO. 76


of water from the sand-and-gravel aquifer. In southern Alabama it is recharged
directly by rainfall where the aquifer is exposed or is near land surface. The
potentiometric surface of the Floridan is highest in northwest Walton County, a
limestone area of low transmissivity. Discharge from the Floridan aquifer is by
leakage to the bay, gulf, and Choctawhatchee River, and by pumping or flowing
wells.

In June 1970 water levels in the Floridan declined more than 80 feet in
southeastern Walton County but remained stable in the northern part of the
county. Recovery to normal levels occurred during the subsequent nonirrigation
season. Floridan aquifer water levels in southern Walton County have declined
0.25 foot per year on the average since 1948 due to increased ground-water use.

Floridan aquifer water in Walton County is of acceptable chemical quality
except in an area adjacent to Choctawhatchee Bay where the water is highly
mineralized. The water becomes more mineralized with depth and along the
coast, from Fourmile Village to Seagrove Beach, the safe useful well depth is
about 500 feet below sea level. A little used zone of the Floridan aquifer along
the coast contains fresh water. Its top is less than 100 feet below land surface
and the aquifer varies in thickness from 90 to 100 feet.

The fresh-saline-water interface in the Floridan aquifer ranges in elevation
from about 650 feet below sea level in the northeastern part of the county to
about 1,200 feet below in the southwestern part. Chloride concentration of
water from wells in the Floridan aquifer has not changed significantly during the
last 10 years.

Total water use in Walton County in 1970 averaged 13.2 mgd of which
12.7 mgd was from the Floridan aquifer. Water used for irrigation averaged 10
mgd and exceeded all other uses. Recreation is the principal use of the lakes and
streams of the county.

Pumpage from the Floridan aquifer did not exceed the safe aquifer yield
during 1970. However, if irrigation pumpage in southern Walton County exceeds
that of 1970, the potentiometric surface should be expected to fall below sea
level in the coastal area.

The inland water-table lakes were formed by the solution and collapse of
the underlying limestone. They contain water low in dissolved solids. During
storms the coastal lakes are subjected to inflow of water from the gulf and are
usually brackish. Streams originating in the county discharge on the average, 1.0
bgd. Minimum streamflow is approximately 300 mgd. Seepage from the
sand-and-gravel aquifer accounts for their high base flow. Surface water in





58 BUREAU OF GEOLOGY

Walton County is low in dissolved solids but is objectionable in that it is
corrosive, colored, and turbid. Nutrient and bacteriological analyses of water
from selected streams indicate little pollution. Irrigation return water that
reached Magnolia and Seven Runs Creeks changed their chemical quality.
Specific conductance increased from 25 to 90 micromhos at Magnolia Creek and
from 20 to 70 micromhos at Seven Runs Creek. Samples of stream-bottom
sediments collected at Magnolia Creek indicated the presence of pesticides in
1970 where there had been none in 1969.







REPORT OF INVESTIGATION NO. 76 59

REFERENCES

Cooke, C.W.
1939 Scenery of Florida interpreted by a geologist: Florida Geol. Survey, Bull. 17.

Hem, J.D.
1970 Study and interpretation of the chemical characteristics of natural water: U. S.
Geol. Survey Water-Supply Paper 1473, second edition.

Marsh, O.T.
1966 Geology of Escambia and Santa Rosa Counties, western Florida Panhandle:
Florida Geol. Survey, Bull. 46.

Martens, J.H.C.
1931 Beaches of Florida: Florida Geol. Survey, 21-22nd Ann. Rept.

Meinzer, O.E.
1923 Outline of ground-water hydrology: U.S. Geol. Survey Water-Supply Paper
494.

Musgrove, R.H., Barraclough, J.T., and Marsh, O.T.
1961 Interim report on the water resources of Escambia and Santa Rosa Counties,
Fla.: Florida Geol. Survey, Inf. Circ. 30.

Parker, G.G., Ferguson, G.E., Love, S.K., and others
1955 Water resources of southeastern Florida, with special reference to geology and
ground water in the Miami area: U.S. Geol. Survey Water-Supply Paper 1255.

Pascale, C.A., Essig, C.F., Jr., Herring, R.R.
1972 Records of hydrologic data, Walton County, Fla.: Florida Dept. Nat.
Resources, Bur. Geology, Inf. Circ. 78.

Riggs, H.C.
1968 Mean streamflows from discharge measurements: U.S. Geol. Survey Prelim.
Rept.

Sellards, R.H., and Gunter, H.
1918 Geology between the Apalachicola and Ochlockonee Rivers in Fla.: Florida
Geol. Survey 10th-llth Ann. Repts.

Stringfield, V.T.
1936 Artesian water in the Floridian Panhandle: U.S. Geol. Survey Water-Supply
Paper 773-C.

Theis, C.V.
1935 The relation between the lowering of the piezometric surface and the rate and
duration of discharge of a well using ground water storage: Am. Geophys.
Union Tran., p. 519-524.

U.S. Dept. Interior
1968 Water quality criteria: Rept. of the National Technical Advisory Committee to
the Secretary of the Interior.







60 BUREAU OF GEOLOGY

US. Public Health Service
1962 Public Health Service drinking water standards, 1962: U.S. Public Health
Service Pub. 956, 61 p.

Volk, G.M.
1971 Fertilizers and fertilization: University of Florida Bull. 183, 29 p.







REPORT OF INVESTIGATION NO. 76 61


APPENDIX

The following tables list all surface-water sites and primary ground-water sites where
hydrologic data were collected. In table 6, surface-water sites are listed in downstream
order; and the drainage area, type, frequency and period of record are given. Table 7 shows
the well locations, depths, yields, and the type, frequency, and period of record for each.
The well location number refers to latitude and longitude (301637N0860002.1 is lat.
30016'37" north, long. 86000'02", well number 1.).

Information Circular 78, "Records of hydrologic data, Walton County, Florida"
(Pascale and others, 1972), contains the hydrologic data collected in Walton County.

For the convenience of those who prefer the use of metric units, table 8 lists
conversion factors for computing metric units from the English units used throughout the
text.








BUREAU OF GEOLOGY




TABLE 6
SURFACE-WATER DATA-COLLECTION SITES IN WALTON COUNTY

Type of ctrd: A. Standard chemical analysis: D. Discharge and stage: 1. Insecticide and Herbicide analysis: K. Conduclivity; S. Stage; T.
Total culitfrm.
F1-naquacy ulo recrd: d. Dily; p. Periodic: r. Continuous. (25) Total number o samples or measurements or streamflow.


number on
IgmMe I


Drainae Type and Period
area frequency of
(sq. mL) of record record


lscaion
(in downstream order)

12A CHOCTAWHATCIIE-. RIVER BASIN
(12A3 PEA RIVFR)
Eightmlcd Creek near Gaskin

Spinm Branch near (aikin

Limesltu Creek near Gaskin


12A CHOCTAWHATCHEE RIVER BASIN
(12A4 BELOW P-A RIVER)
Morriwn Sprnngsu near Redbly

Sandy Creek near Argyle

Bruce Creek near DeFuniak SprinpWs

DcFunlak Lake at UDeuniak Springs

Bruce Creek near Rcdbay

Seven Run ('reek near Rrdbay

Choctawhatcher River near Bruce


128 COASTAL ARI- A BIETW-FN CHOCTAWHATCHEl-
RIVER AND YELLOW RIVI.R
Black Creek near Bruce

Pate Branch near I report

Maqgnalla Creek near Trretport


Lafaylett Creek near 1-reeport

Fourmale Crek near -recportl

Alaqua Creek near Del-uniak Springs

Basrn Creek near Portland

Rucky Creek near Nicille



YELLOW RIVIR BASIN
Caney Creek near (clndadl

Gum Creek near DeFuniak Springs

Shoal Rsver near Mouy Head

Lake Jackson near Paxrun

Pine Las Creek near FlowerCvill

Lon Creek near Mossy Head

Tilt Creek near Mosy Head


24.9 Dp(25)
A(4). T(2). K(8)
Dp(2)
A(2)
Dp(2)
A(2)




Dp(S)
All)
51.8 Dp(24)
A(3). T(2). K(8)
A(2)
A(2)
Sp(2)
A(2)
51.4 Dp(26)
A13). T(2). K(8)
25.8 Dd
A(3). T(2). K(8)
4.384 Dr
A(3). T(2). K(3



I)p(2)
A12)
Dr
A(2)
11.2 Dr
A(5). T(2). K(8)
1(2)
Dp(2)
A(2)
Dp(1)
A(l). TI)
65.6 Dr
A(3). T(2)
Dp2)
A(2)
67.0 Dr
Dp(10)
A(3).T(2)


Dp(4)
A(2)
Dp(S)
A(2)
123 Dr
A(6). T2)
2 Sd
A(2)
Dp(2)
A(2)
S Dpl2)
A(2)
Dp(2)
A(2)


See


1968-70

1968-70

1969-70





1946-68
1968
1968-70

1969-70

1968-70

1968-70

1968-70

1930-70





1969-70

1968-70

1968-70


1969-70

1970

1951-70

1969-70

1966-68
1968-70




1967-70

1966-70

1951-70

1966-70

1969-70

1969-70

1969-70







REPORT OF INVESTIGATION NO. 76


TABLE 7
GROUND-WATER DATA-COLLECTION SITES IN WALTON COUNTY

Type of record: A, Standard chemical analysis; C, Chloride; P, Partial chemical analysis;
S, Stage.
Frequency of record: i, Intermittently; p, Periodic; r, Continuous; (15), Total number
of samples.


Site
number on
figure 1


88 303103N0862010.2


Location

301637N0860002.1

301946N0860957.1

302058N0861432.1

302112N0861501.1

302214N0860652.1

302221N0860652.1

302231N0862143.1

302243N0860917.1

302346N0861812.1

302357N0861007.1

302444N0860010.1

302549N0860717.1

302619N0860642.1

302637N0855433.1

302708N0860557.1

302721N0861014.1

302912N0861458.1

302929N0860818.1

303027N0860513.1

303040N0861202.1

303053N0860753.1


382 100 Si
A(3)


Depth
(feet)

455

466

340

455

450

365

420

389

400

337

229

240

310

196

932

250

160

125

393

230

207


Type and
Yield frequency
(gpm) of record

210 Si
A(1)
360 Sp
A(1), Cp
Sp
A(1), Cp
15 Si
A(1), Pi
Sp
A(1), Cp
Sp
Cp
Sp
A(1), Cp
Si
A(l)
Si
A(1), Pi
50 Sp
A(1), Cp
Si
A(1), Pi
Si, Ci
A(1), Pi
Si
Pi
Sp
Cp
Sp
Cp
1,700 Sp
Cp
Sp
Cp, Pi
Sr
Pi
975 Si
Pi
Sp

Sr


Period
of
record

1968

1961-70

1968-70

1970

1946-69

1970

1968-70

1970

1969-70

1961-70

1969-70

1969-70

1969-70

1968-70

1968-70

1968-70

1961-70

1968-70

1969-70

1968-70

1968-70

1965c67






BUREAU OF GEOLOGY


91

92

93

95

96

97

99

100

101

102

103

104

106

112

121

129

130

131

134

147

149

151

161

162

163

164

165


303214N0855804.1

303214N0855804.2

303223N0855704.1

303348N0860224.1

303348N0860224.2

303417N0855731.1

303426N0860611.1

303426N0860611.2

303434N0861303.1

303443N0861939.1

303454N0855606.1

303456N0861916.1

303545N0860646.1

303937N0861257.1

304044N0862116.1

304310N0860706.1

304334N0860324.1

304335N0860319.1

304358N0861208.1

304914N0861842.1

304950N0862322.1

305043N0860833.1

305732N0860208.1

305804N0861809.1

305816N0860815.1

305828N0861809.1

305359N0861226.1


506

23

585

440

18

440

440

32

440

452

300

60

440

620

630

621

236

372

509

700

455

320

120

350

80

420

250


965 Sr
A(1)
Sp

1,050 Si
Pi
900 Sp
Pi
Sp

Sp
Pi
1,100 Sr
A(1), Pi
Sp

278 Sp
Pi
150 Si
A(7)
Sp
Pi
5 Sr
A(1)
27 Sp
A(1)
125 Sp
A(1)
250 Sp
A(15)
640 Si
A(1)
Sp
Pi
380 Si
Pi
Sp
A(1)
1,200 Si
Pi
Sr

Sp
A(1)
Si
A(1)
50 Sp
A(1)
Si
A(1)
430 Si

Sp


1968-70

1969-70

1968-70

1968-70

1969-70

1968-70

1968-70

1969-70

1968-70

1960-70

1968-70

1967-70

1968-70

1968-70

1947-51,
1966-70
1969-70

1968-70

1970

1961-70

1970

1968-70

1968-70

1969-70

1968-70

1969-70

1969

1968-70







REPORT OF INVESTIGATION NO. 76


TABLE 8
FACTORS FOR CONVERTING ENGLISH UNITS
TO INTERNATIONAL SYSTEM (SI) UNITS


The following factors may be used to convert
International System of Units (SI).


the English units published herein to the


Multiply English units By To obtain SI units


inches (in)

feet (ft)
miles (mi)


Length
25.4 Le
.0254
.3048
1.609


millimeters (mm)
meters (m)
meters (m)
kilometers (km)


acres


square miles (mi2)


Area
4047
.4047
.4047
.004047
2.590


square meters (m2)
hectares (ha)
square hectometer (hm2)
square kilometers (km2)
square kilometers (km2)


gallons (gal)



million gallons (106 gal)

cubic feet (ft3)

acre-feet (acre-ft)





cubic feet per second (ft3/s)



gallons per minute (gpm)



million gallons per day (mgd)




cubic feet per second
per square mile (cfsm)


Volume
3.785
3.785
3,785x10-3
3785
3.785xl0-3
28.32
.02832
1233
1.233x10-3
1.233x10-6

Flow
28.32
28.32
.02832
.06309
.06309
6.309x10-s
43.81
.04381

Flow per Unit Area


.01093


liters (1)
cubic decimeters (dm3)
cubic meters (m3)
cubic meters (m3)
cubic hectometers (hm3)
cubic decimeters (dm3)
cubic meters (m3)
cubic meters (m3)
cubic hectometers (hm3)
cubic kilometers (km3)



liters per second (1/s)
cubic decimeters per second (dm3/s)
cubic meters per second (m3/s)
liters per second (1/s)
cubic decimeters per second (dm3/s)
cubic meters per second (m3/s)
cubic decimeters per second (dm3/s)
cubic meters per second (m3/s)



cubic meters per second per square
kilometer (m3/s/km2)


Specific Capacity


gallons per minute
per foot (gpm/ft)



gallons per minute
per foot (gpd/ft)


2.07xl0-4


cubic meters per second
per meter (m3/s/m)


Transmissivity


square meters per day (m2/day)


.0124