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Ground water in Seminole county, Florida ( FGS: Report of investigations 1 )
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 Material Information
Title: Ground water in Seminole county, Florida ( FGS: Report of investigations 1 )
Series Title: ( FGS: Report of investigations 1 )
Physical Description: 2 p. l., 13 numb. l., 1 l. : map. ; 28 cm.
Language: English
Creator: Stringfield, V. T ( Victor Timothy ), 1902-
Publisher: s.n.
Place of Publication: <Tallahassee>
Publication Date: 1934
 Subjects
Subjects / Keywords: Groundwater -- Florida -- Seminole County   ( lcsh )
Water-supply -- Florida -- Seminole County   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by V. T. Stringfield. Prepared in cooperation between the United States Geological survey and the Florida Geological survey.
Bibliography: Bibliographical foot-notes.
General Note: Mimeographed.
 Record Information
Source Institution: University of Florida
Rights Management:
The author dedicated the work to the public domain by waiving all of his or her rights to the work worldwide under copyright law and all related or neighboring legal rights he or she had in the work, to the extent allowable by law.
Resource Identifier: aleph - 000955573
oclc - 01742519
notis - AER8200
lccn - gs 35000103
System ID: UF00001185:00001

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Table of Contents
    Title Page
        Title Page 1
        Title Page 2
    Table of Contents
        Table of Contents
    Map
        Unnumbered ( 5 )
    Introduction
        Page 1
        Page 2
        Page 3
        Page 4
    Topography
        Page 5
        Page 6
        Page 4
        Page 7
    Climate
        Page 6
    Geology
        Page 8
        Page 9
        Page 7
    Ground water
        Page 10
        Page 9
        Page 11
        Page 12
        Page 13
    Conclusions
        Page 14
        Copyright
            Copyright
        Page 13
Full Text




FLORIDA
STATE BOARD OF, CONSERVATION
Geo6rd W. Davis
Supervisor of Conservation
GEOLOGICAL DEPARTMENT
Herman Gunter
Assistant Supervisor


REPORT OF INVESTIGATIONS

NO. 1




* * *. **


GROUND WATER IN SEMINOLE COUNTY, FLORIDA

By

V. T. Stringfield


Prepared in cooperation between
the United States Geological Survey
and the Florida State Geological Survey.


Fourth mimeographing August 1, 1951.


19 34

















CUALTAR
Ut~IARY:


I.: 1


I


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nGcl


-I,'?

r














CONTENTS







Page


Introduction .... ................................ ..... 1

Location and area ................................. 1

Population and development ..................... 1

Previous investigations ......................... 2

Present investigations: ....e.. .................... 3

Topography *... .*.... .... ........... ...... ...... .... 4

Relief ..... ......... ... ..................... ... 4

Drainage .............. .......... ........ ..... 5

Climate ...................... ....................... 6

Geology ................ ................ .... .......... 7

Ground water ........ .. ... *.... ........ .... ........... 9

Development .... .... .. ............................. 9

Artesian conditions ........ .................... 10

Fluctuation of head ................ ............... 12

Quality ............... ............................ 12

Conclusions ...... .. ........ ...................... 13



















GROUND WATER IN SEMINOLE
COUNTY, FLORIDA


By le

V. T. Stringfield ,



\^--i-<
Shaded area indicates location .-
of Seminole County.


FLO I.-Jr





FLORIDA



SCALE O 4S 40 MnLS


,.mea.,'











INTRODUCTION

Location and area



Seminole County is in the east-central part of the Florida

peninsula. It is bounded on the north and east by the St. Johns River,

on the south by Orange County, and on the west by Orange County and the

Wekiva River. It has a land area of 321 square miles.


Population and development


The population of the county, in 1930, according to the Federal

Census, was 18,735. Sanford, the county seat and the largest town, is

in the northern part of the county, on Lake Monroe. In 1930 it had a

population of 10,000. Oviedo, in the south-central part of the county

about 2 miles south of Lake Jessup, had a population of 1,042. The other

towns in the area had less than 1,000 each.

The county leads in the production of celery in Florida and is one

of the chief vegetable-growing centers of the State. During 1929 the

value of the celery crop from farms with a total of 3,736 acres was re-

ported by the United States Department of Commerce to be $2,889,673.

Although the rainfall is fairly large, the vegetable crops, especially

celery, require irrigation, and the water used for this purpose is

obtained from artesian wells.











Previous investigations


The geology and ground water of Florida are described in

several reports prepared by the State Geological Survey of Florida

or by the United States Geological Survey. The ground water of

Seminole County is mentioned in a number of these reports. In 1913

Matson1 described briefly the geology and ground water of Orange County,

which then included the area known as Seminole County. The same year a

report by Sellards and Gunter2 included a statement concerning the wells

in Seminole County. A report by Mossom in 1926 described the general

features of the geologic structure of the State. The most recent detailed

description of the geology of the State is given in a report by Cooke

and Mossom which includes a map showing the distribution of the geologic

formations at or near the surface. Analysis of water samples from sev-

eral wells in Seminole County are included in a report by Collins and

Howard5.



1. Matson, G. C., and Sanford, Samuel, Geology and ground waters of
Florida: U. S. Geol. Survey Water-Supply Paper 319, pp. 376-381,
1913.

2. Sellards, E. H., and Gunter, Herman, The artesian water supply
of eastern and southern Florida: Florida Geol. Survey 5th Ann.
Rept. p. 113, 1913.

3. Mossom, Stuart, A review of the structure and stratigraphy of
Florida: Florida Geol. Survey 17th Ann, Rept. pp. 171-268, 1926.

4. Cooke, C. ., and Mossom, Stuart, Geology of Florida: Florida Geol.
Survey 20th Ann. Rept., pp. 29-228, 1929.

5. Collins, W. D., and Howard, C. S., Chemical character of the waters
of Florida: U. S. Geol. Survey Water-Supply Paper 596, p. 228, 1928.

4-20










Present investigations


The work whose results are here recorded was undertaken as a

part of a comprehensive investigation of the ground-water resources of

the State, provided by a cooperative-agreement made in 1930 between the

Florida Geological Survey and the United States Geological Survey. The

work is under the supervision of 0. E. Meinzer, geologist in charge of

the division of ground water, United States Geological Survey, and Herman

Gunter, state geologist of Florida. On June 30, 1933, the cooperative

work was discontinued because of lack of funds. Several reports on

the investigation in other parts of the State have been prepared under

this cooperative agreement.

During May 1933 observations were made in Seminole County in

connection with the investigation of ground water started in Orange and

Seminole counties in 1930.2 The work in Orange County was principally

concerned with the problems relating to drainage wells. A few drainage
--------------------- -----------MW---- M-------
1. Thompson, D. G., and Stringfield, V. T., Ground-Water Resources
of Florida: Florida Geol. Survey Press Bull. 13, April 1931.

Thompson, D. G., Problems of ground-water supply in Florida:
American Water Works Assoc. Jour. Vol. 23, No. 12, pp. 2085-2100,
December 1931.

Stringfield, V. T., Ground-water resources of Sarasota County,
and exploration of artesian wells in Sarasota County, Florida:
Florida Geol. Survey 23rd and 24th Ann. Repts., 1933.

Stringfield, V. T., Ground-water investigations in Florida:
Florida Geol. Survey Bull. 11, 1933.

Stringfield, V. T., Ground-water in the Lake Okeechobee area,
Florida (unpublished),

2. Stringfield, V. T., Ground-water investigations in Florida:
Florida Geol. Survey Bull. 11, 1933.


"3-










wells have been constructed in the southern part of Seminole County,

but the principal ground-water problem in that county relates to the

water available for irrigation and public supplies. /In two irrigation

districts, those of Sanford and Oviedo, where large supplies of water

for irrigation are obtained from artesian wells, some of the water is

highly mineralized. This is significant, because the highly mineralized

water is undesirable for irrigation and because with heavy draft the water

from many of the wells now yielding water of comparatively low mineral

content may become more highly mineralized. Moreover, with increased

draft from wells the artesian pressure may be lowered to such an extent

that many of the wells will stop flowing.

In May.1933 data relating to wells, -ground water, and the forma-

tions penetrated by wells were obtained, and field tests of the chloride

content of samples of water from representative wells were made.

The writer is indebted to the well drillers, owners of wells, and

other citizens who have contributed information to this investigation.

J. Clarence Simpson, of the State Geological Survey, assisted in the field

work.


Topography

Relief


Seminole County lies partly in an upland known as the lake region

that extends northward and eastward toward the St. Johns River, where it

is succeeded by a broad comparatively flat lowland. Surface altitudes


-4-











range from more than 100 feet in the upland to less than 25 feet in the

lowland. In the northeastern and eastern part of the county and along

the south shore of Lake Jessup the land rises abruptly into the upland

area. The upland area is undulating and has many lakes that occupy

depressions, probably formed by the solution of the underlying limestone.

Lake Jessup, Lake Monroe, and Lake Harney are the largest lakes in the

county and probably fill original depressions in the floor of the sea

that once covered this area. It has been suggested that the depression

in which Lake Jessup lies was formed in part by old stream meanders,

antedating the last invasion of the sea. Lake Jessup, about 9 miles long

and 3 miles wide, extends from the central part of the county northward

to the St. Johns River, Lake Monroe, and Lake Harney are the course of the

St. Johns.


Drainage


The St. Johns River controls the drainage of the county. It

forms the east and north boundary and flows northward to the northeastern

part of the State and thence into the Atlantic Ocean. The Wekiva River

forms part of the west boundary of the county and flows northward into the

St. Johns River. The Little Wekiva River rises in the southwestern part

of the county and flows northward into the Wekiva. Palm Spring and

Sanlando Springs are the tributaries to it. Lake Jessup and the creeks

that empty into it afford drainage for the central part of the county.


Leverett, Frank, The Pensacola terrace and associated beaches and bars
in Florida: Florida Geol. Survey Bull. 7, p. 12, 1931.


-5-











The Econlockhatchee River rises in Orange County, flows northward into

Seminole County for a distance of about 5 miles, and thence eastward and

northeastward to the St. Johns River. The Econlockhatchee River and its

tributaries together with a few creeks flowing into the St. Johns River

afford drainage for the southeastern part of the county. Sweetwater

Branch appears to have been formerly a "lost stream" or "disappearing

stream" such as might be expected in areas where sink holes are present.

It rose about 2 miles north of Oviedo, flowed southward and drained into

a sink hole that formerly existed just north of Oviedo. At the present

time Sweetwater Branch drains northward through a ditch into Lake Jessup.


Climate


Climatic observations by the United States Weather Bureau were

begun at Sanford in 1883, but apparently no temperature records were kept

between 1887 and 1913.

Monthly and annual temperature, in degrees Fahrenheit, at Sanford.


(U. S. WEATHER BUREAU)



Year Jan. Feb.- Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Ann.


1932 67.6 71.0 64.2 70.8 76.6 81.2 86.2 83.4 79.8 75.0 64.6 66.2 73.9

1913
to 60.1 62.7 65.8 70.4 75.6 79.7 81.4 81.6 79.8 74.2 66.4 60.8 71.6
1932
Immme mm~------------------------------------ m~wmm ,mmmmm mm mm m


-6-










wells have been constructed in the southern part of Seminole County,

but the principal ground-water problem in that county relates to the

water available for irrigation and public supplies. /In two irrigation

districts, those of Sanford and Oviedo, where large supplies of water

for irrigation are obtained from artesian wells, some of the water is

highly mineralized. This is significant, because the highly mineralized

water is undesirable for irrigation and because with heavy draft the water

from many of the wells now yielding water of comparatively low mineral

content may become more highly mineralized. Moreover, with increased

draft from wells the artesian pressure may be lowered to such an extent

that many of the wells will stop flowing.

In May.1933 data relating to wells, -ground water, and the forma-

tions penetrated by wells were obtained, and field tests of the chloride

content of samples of water from representative wells were made.

The writer is indebted to the well drillers, owners of wells, and

other citizens who have contributed information to this investigation.

J. Clarence Simpson, of the State Geological Survey, assisted in the field

work.


Topography

Relief


Seminole County lies partly in an upland known as the lake region

that extends northward and eastward toward the St. Johns River, where it

is succeeded by a broad comparatively flat lowland. Surface altitudes


-4-











The season of heavy rainfall usually includes the summer and

early fall. In this season the rainfall comes in showers and may be

irregularly distributed. The average annual precipitation1 is 50 to

55 inches except in the northwestern part of the county where it is less

than 50 inches.


Monthly and annual precipitation, in inches, at Sanford.


(U. S. Weather Bureau)


Jan. Feb. Mar. Apr. May June



1.48 0.34 3.07 0.99 5.25 8.03


2.21 2.11 3.08 2.80 4.02 7.21
!L
i .....


July Aug. Sept. Oct.



0.85 8.45 4.27 1.53


7.57 6.31 5.99 5.46


Nov. Dec. Ann.



5.09 0.06 39.41


1.70 2.58 51.04


. ^ .. ^ .L ^


t


Geology

The geologic formations that underlie Florida are described

in a report by Cooke and Mossom2, which includes a map showing the

distribution of the formations at or near the surface. In Seminole

County the Ocala limestone, of Eocene age, is present about 50 to 150

feet below the surface. The formation is underlain by undifferentiated


Map showing normal annual temperature and precipitation as compiled
from all available records to 1920, inclusive: U. S. Weather Bureau
Climatological Data, Florida section, Vol. 34, No. 13, opposite p. 52,
1930.


Cooke, C. W., and Mossom, Stuart, op. cit., pp. 31-227.
-7-


Year



1932

1883
to
1932

"MMMM.











The Econlockhatchee River rises in Orange County, flows northward into

Seminole County for a distance of about 5 miles, and thence eastward and

northeastward to the St. Johns River. The Econlockhatchee River and its

tributaries together with a few creeks flowing into the St. Johns River

afford drainage for the southeastern part of the county. Sweetwater

Branch appears to have been formerly a "lost stream" or "disappearing

stream" such as might be expected in areas where sink holes are present.

It rose about 2 miles north of Oviedo, flowed southward and drained into

a sink hole that formerly existed just north of Oviedo. At the present

time Sweetwater Branch drains northward through a ditch into Lake Jessup.


Climate


Climatic observations by the United States Weather Bureau were

begun at Sanford in 1883, but apparently no temperature records were kept

between 1887 and 1913.

Monthly and annual temperature, in degrees Fahrenheit, at Sanford.


(U. S. WEATHER BUREAU)



Year Jan. Feb.- Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Ann.


1932 67.6 71.0 64.2 70.8 76.6 81.2 86.2 83.4 79.8 75.0 64.6 66.2 73.9

1913
to 60.1 62.7 65.8 70.4 75.6 79.7 81.4 81.6 79.8 74.2 66.4 60.8 71.6
1932
Immme mm~------------------------------------ m~wmm ,mmmmm mm mm m


-6-













Eocene sediments and is overlain by the Hawthorn formation, of Miocene

age, which in turn is overlain by a mantle of undifferentiated Pleis-

tocene and Recent materials. The total thickness of the Ocala formation

is not known, but it is estimated to be about 500 feet. It is the oldest

formation penetrated by wells drilled for water in the county. In parts

of Florida the Tampa limestone, of Miocene age, lies between the Ocala

limestone and the Hawthorn formation, but in Seminole County the Tampa

is believed to be absent, and the upper surface of the Ocala is apparently

an irregular eroded surface on which the Hawthorn rests. The Ocala under-

lies all of the Florida peninsula and is at or near the surface in Sumter

County, about 35 miles west of Seminole County, and in other counties in

the west-central part of the peninsula.-

The Ocala formation consists of almost pure limestone with some

chert. Parts of the limestone are porous and contain solution channels

that permit free circulation of ground water. According to the reports

of drillers, many of the wells penetrating the Ocala limestone in Seminole

and Orange counties encounter cavities with vertical dimensions of as much

as 20 feet, whereas in other parts of the peninsula where the formation

is deeply buried no cavities have been reported. It thus appears that

solution channels occur in the limestone where it is or has been at the

surface or at moderate depths below the surface. Old solution channels

now filled with sand or clay are exposed in some of the quarries in the


-8-












Ocala limestone in Marion County. Numerous sink holes that formerly

connected underground channels with the surface are now filled with sand

and clay. These filled sinks are reported by drillers to be common in

parts of Seminole County, and in selecting locations for wells depressions

resembling old sinks are avoided, because in some of them sand has been

encountered to a depth of more than 200 feet, whereas normally limestone

that yields water may be encountered at a depth of about 50 feet. Such

a condition is reported to exist in the topographic depression just north

of Oviedo,

In Seminole County the Hawthorn formation consists of interbedded

marl, clay, and sand. The surficial Pleistocene and Recent material

consists chiefly of sand, marl, clay, or muck.


Ground Water

Developments


Small domestic supplies of water are obtained in Seminole County

from shallow wells that end in the surficial sands. Most of these are

driven wells that are equipped with hand pumps. A few supplies are also

obtained from wells that yield water from the Hawthorn formation. The

chief source of ground water, however, consists of drilled wells that ex-

tend into the Ocala limestone and yield water that is under artesian

pressure. It is estimated that there are about 1,500 drilled wells in

the county, most of which are in the celery districts, near Sanford and

Oviedo. Some of the fields have an average of one well for each acre of


-9-











The season of heavy rainfall usually includes the summer and

early fall. In this season the rainfall comes in showers and may be

irregularly distributed. The average annual precipitation1 is 50 to

55 inches except in the northwestern part of the county where it is less

than 50 inches.


Monthly and annual precipitation, in inches, at Sanford.


(U. S. Weather Bureau)


Jan. Feb. Mar. Apr. May June



1.48 0.34 3.07 0.99 5.25 8.03


2.21 2.11 3.08 2.80 4.02 7.21
!L
i .....


July Aug. Sept. Oct.



0.85 8.45 4.27 1.53


7.57 6.31 5.99 5.46


Nov. Dec. Ann.



5.09 0.06 39.41


1.70 2.58 51.04


. ^ .. ^ .L ^


t


Geology

The geologic formations that underlie Florida are described

in a report by Cooke and Mossom2, which includes a map showing the

distribution of the formations at or near the surface. In Seminole

County the Ocala limestone, of Eocene age, is present about 50 to 150

feet below the surface. The formation is underlain by undifferentiated


Map showing normal annual temperature and precipitation as compiled
from all available records to 1920, inclusive: U. S. Weather Bureau
Climatological Data, Florida section, Vol. 34, No. 13, opposite p. 52,
1930.


Cooke, C. W., and Mossom, Stuart, op. cit., pp. 31-227.
-7-


Year



1932

1883
to
1932

"MMMM.











land under cultivation; others may average only one well for as much

as 5 acres. These wells range from about 2 to 8 inches in diameter and

from about 50 to more than 300 feet in depth. However, most of them are

between 2 and 5 inches in diameter and between 75 and 250 feet in depth.

They are cased to depths of about 20 to 80 feet. Most of the wells will

flow under artesian pressure with yields ranging from only a few gallons

to more than 100 gallons a. minute. The wells on higher ground do not

flow, but the water rises in them to a level within a few feet of the

surface. Two wells of this type at Oviedo and a few in the southwestern

part of the county are used for drainage. Nonflowing wells yield water

from the Ocala limestone for the public water supply of Sanford.


Palm and Sanlando Springs, in the southwestern part of the county,

have been developed for swimming and recreation. These springs are the

largest in the county. It appears that their water is derived from the

Hawthorn formation, but some of it may be coming from the Ocala limestone.

There are a few small springs on the south side of Lake Jessup and in

the valley of the St. Johns River. Water from Elder Spring, a few miles

south of Sanford is soft and is bottled and sold for drinking. It comes

from the surficial sands.


Artesian conditions


The Ocala limestone contains water under artesian pressure

throughout Seminole County and supplies many flowing wells in the low


-10-












Ocala limestone in Marion County. Numerous sink holes that formerly

connected underground channels with the surface are now filled with sand

and clay. These filled sinks are reported by drillers to be common in

parts of Seminole County, and in selecting locations for wells depressions

resembling old sinks are avoided, because in some of them sand has been

encountered to a depth of more than 200 feet, whereas normally limestone

that yields water may be encountered at a depth of about 50 feet. Such

a condition is reported to exist in the topographic depression just north

of Oviedo,

In Seminole County the Hawthorn formation consists of interbedded

marl, clay, and sand. The surficial Pleistocene and Recent material

consists chiefly of sand, marl, clay, or muck.


Ground Water

Developments


Small domestic supplies of water are obtained in Seminole County

from shallow wells that end in the surficial sands. Most of these are

driven wells that are equipped with hand pumps. A few supplies are also

obtained from wells that yield water from the Hawthorn formation. The

chief source of ground water, however, consists of drilled wells that ex-

tend into the Ocala limestone and yield water that is under artesian

pressure. It is estimated that there are about 1,500 drilled wells in

the county, most of which are in the celery districts, near Sanford and

Oviedo. Some of the fields have an average of one well for each acre of


-9-











parts of the county. Water enters the formation in areas where it is

at or near the surface in the central part of the peninsularand in

places where it is overlain by permeable rocks that permit free downward

percolation. Water also enters the.formation through drainage wells in

Orange and Seminole counties. The Hawthorn formation contains relatively

impervious strata that prevent or retard upward percolation of water

from the Ocala. In some parts of the county this impervious material is

absent or comparatively thin, or it may be fractured, permitting water

from the Ocala limestone to reach the surface. On the development of one

of the drainage canals north of Oviedo water under artesian pressure was

encountered at a depth of about 15 to 20 feet. Water under artesian

pressure is also encountered at depths of less than 50 feet under spring

mounds in that locality. The spring mounds are domes about 50 to 100 feet

in diameter and extending about 4 to 5 feet above the surface. They appear

to be formed in places where the confining beds do not prevent some seep-

age of the artesian water to the surface. The water thus appearing at the

surface supplies the overburden of peat with moisture in excess of that

in adjacent areas and thereby retards the rate of shrinkage in the peat

at the spring, as compared with the shrinkage in adjacent areas.


The area in which flowing wells may be obtained includes all of the

lowland bordering the St. Johns River, the Econlockhatchee River, Lake

Monroe, Lake Jessup, and Lake Harney. In the vicinity of Sanford the


-11-











artesian head is about 30 feet with reference to sea level. In the

southwestern part of the county and in the adjacent part of Orange

County the artesian head is somewhat higher, indicating that there is a

movement of the water toward the northeast and that the intake area is

southwest or west of Seminole County.



Fluctuation of head


Fluctuation of artesian head may be caused by a number of con-

ditions. According to reports of well owners the largest fluctuations

occur during the irrigation seasons in periods of heavy draft. These are

caused in part by opening and closing of many wells and pumping of wells

in irrigation districts. When a large number of wells are in use there

is a lowering of the artesian head, and when the wells are closed there is

ani increase in head. Increase in head is especially noticeable after

rains, not because of recharge produced by the rains but because the wells

used for irrigation are closed in rainy weather and the draft of water is

in consequence greatly reduced. There are also fluctuations caused chiefly

by recharge in the intake area.



Quality


In general the water from shallow wells terminating in the sur-

ficial sands is reported to be soft and low in mineral content except in


-12-











certain localities in the eastern and northeastern parts of the county.

Water from the Ocala limestone and Hawthorn formation is hard, and

some of it in the eastern and northeastern parts of the county is highly

mineralized and harmful to crops irrigated with it.


Field tests of the chloride content of samples of water from

numerous wells were made in order to indicate the relative saltiness.

Water has a distinct salty taste if it contains as much as 1,000 parts

per million of chloride, and in order to be acceptable to most people for

drinking it should contain less than 250 parts per million, The field

tests indicate that the chloride content of ground water in Seminole

County ranges from less than 50 parts per million in the southwestern

part of the county to more than 5,000 parts in some wells in the north-

eastern part. The area in which the water is relatively high in chloride

includes a large part of the Sanford and Oviedo celery districts. A

few measurements of the artesian head in different parts of the county

indicate that the highly mineralized water is found in a general way in

areas 'of relatively low head.



Conclusions


The preliminary work shows that a detailed investigation is

needed to determine the proper course to follow in the protection, con-

servation and further development of the artesian water supply, which

is very valuable for irrigation and for public and domestic use. In


-13-











part of the county the artesian water is already too highly miner-

alized to be suitable for irrigation or for domestic or public water

supplies. These areas of high mineralization should be definitely out-

lined, and the adjacent districts should be carefully studied to determine

whether the highly mineralized water is encroaching on the areas of low

mineralization. If encroachment caused by draft fromrwells is taking

place, methods can be adopted for preventing or retarding the process.

A careful study of the pressure heads or water levels in wells throughout

the county will give much needed information regarding the fluctuation of

water levels, the extent of the permanent loss of head that is taking

place, the direction of flow of the artesian water, and the effect of

withdrawals of water on the mineralization.


-14-










FLRD GEOLOSk ( IC SUfRiW


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certain localities in the eastern and northeastern parts of the county.

Water from the Ocala limestone and Hawthorn formation is hard, and

some of it in the eastern and northeastern parts of the county is highly

mineralized and harmful to crops irrigated with it.


Field tests of the chloride content of samples of water from

numerous wells were made in order to indicate the relative saltiness.

Water has a distinct salty taste if it contains as much as 1,000 parts

per million of chloride, and in order to be acceptable to most people for

drinking it should contain less than 250 parts per million, The field

tests indicate that the chloride content of ground water in Seminole

County ranges from less than 50 parts per million in the southwestern

part of the county to more than 5,000 parts in some wells in the north-

eastern part. The area in which the water is relatively high in chloride

includes a large part of the Sanford and Oviedo celery districts. A

few measurements of the artesian head in different parts of the county

indicate that the highly mineralized water is found in a general way in

areas 'of relatively low head.



Conclusions


The preliminary work shows that a detailed investigation is

needed to determine the proper course to follow in the protection, con-

servation and further development of the artesian water supply, which

is very valuable for irrigation and for public and domestic use. In


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