Title: Draft - Water Supply Needs and Sources Assessment - Appendix A - October 1992
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Title: Draft - Water Supply Needs and Sources Assessment - Appendix A - October 1992
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Abstract: Jake Varn Collection - Draft - Water Supply Needs and Sources Assessment - Appendix A - October 1992 (JDV Box 90)
General Note: Box 24, Folder 2 ( Emerging Issues and Conflicts - 1976-1994 ), Item 4
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APPENDIX A


DRAFT WATER SUPPLY NEEDS AND SOURCES ASSESSMENT
OCTOBER 1992








Draft









WATER SUPPLY


NEEDS AND SOURCES ASSESSMENT



NOTE: The information contained in this document is substantially the same
as that presented in Section III.A.1. of the 1992 Draft district water management
plan: St. Johns River Water Management District.










St. Johns River Water Management District
Palatka, Florida
October 1992












List of Tables .................


List of Figures


. . . . . . . . . . . . v


INTRODUCTION ............................................. 1

WATER RESOURCE ASSESSMENT ............................... 1

W ater U se .............................................. 2
Ground Water and Surface Water Model Development ........... 7
Im pact Assessm ent ...................................... 20
Impact Criteria Development .............................. 26
Delineation of Water Resource Problem Areas ............ ...... 28

WATER SUPPLY ALTERNATIVES ............................... 29

Supply Enhancement .................................... 29
Demand Management ................................... 31

WATER MANAGEMENT STRATEGIES ........................... 31

Policy Fram ew ork ....................................... 32
Guiding Principles ...................................... 32
Im plem entation ......................................... 32


Literature Cited ................


CONTENTS


. . . . . . . . iv









TABLES

1 Public supply and agricultural water use for 1990 and 2010 ........ 4

2 Change in public supply water use from 1990 to 2010 ............ 6

3 Regional ground water flow model summary .................. 12

4 Gauged stream sites in the St. Johns River Water Management District
with daily discharges of record exceeding 10 cubic feet per second 19









FIGURES

1 Generalized east-west hydrogeologic cross-section of the St. Johns River
W ater Management District ................................ 8

2 Areas where concentrations of chlorides, sulfates, and total dissolved
solids exceed secondary drinking water standards in the Upper Floridan
aquifer .................... ..... ...................... 11

3 Regional ground water flow model areas, St. Johns River Water
M anagem ent District ..................................... 14

4 Potentiometric surface of the Upper Floridan aquifer in 2010 ...... 22

5 Potentiometric surface of the Upper Floridan aquifer in 1988 :....... 23

6 Difference between the simulated 2010 and 1988 potentiometric surface
of the Upper Floridan aquifer .............................. 24

7 Projected changes in the surficial aquifer water table between 1988 and
2010 ...... ......................... ................. 25

8 Areas of potential impact to plant communities resulting from projected
changes in ground water withdrawals between 1988 and 2010 ..... 27









WATER USE


Water use needs have been inventoried and projected to the year 2010 for
several use categories. Projections of future water use are based on historical
trends, local government comprehensive plans, and direct communication with
public and private public supply utilities.

Current Water Use

Current water use data were obtained from SJRWMD's Annual water use
survey: 1990 (Florence 1992 draft). Estimates of 1990 public supply and
agricultural water use by county are provided later on pages 4-6 (Tables 1 and
2). Counties with the largest public supply consumption in 1990 were Orange
County (127.28 mgd) and Duval County (96.32 mgd), while Indian River
County (168.57 mgd) and Brevard County (111.18 mgd) consumed the most
water for agriculture (and golf course use). Estimates for the other water use
categories as well as definitions and descriptions of how the data were
developed are available in the Annual water use survey: 1990 (Florence 1992
draft).

Most public water supply systems (55 percent) are privately owned, but more
water is provided by local government-owned systems. Privately owned
systems tend to be smaller than publicly owned systems. The eight largest
systems, all operated by local governments, provided over one-half (52
percent) of all public supply system water. The 18 largest systems (including
only 4 privately owned) provided 70 percent of all public supply water. None
of the remaining 213 systems provided over 5 mgd or one percent of the total
amount of public supply water.

Total fresh water use for agriculture and golf courses was 605.31 mgd in 1990,
or about 58 percent of total public and agriculture water use (Florence 1992
draft). Most ground water used for agricultural irrigation came from the
Floridan aquifer.

Projected 2010 Water Use

Projections of water use for the year 2010 were obtained by a variety of means,
depending on the type of information available and the existence of trends in
the data. These projections and the methods by which they were derived are
considered to be provisional.








Public supply water use projections for the year 2010 are based on information
contained in local government comprehensive plans, water use master plans,
consumptive use permit files, and information provided through direct
conversations with public suppliers. Public supply water use projections
reflect the plans of individual public suppliers and were not made
independently by SJRWMD unless water use projections were not furnished by
suppliers.

Agricultural irrigation and golf course irrigation water use projections are
based on methodologies outlined in Institute of Food and Agricultural Sciences
publications entitled Needs and sources planning in the St. Johns River Water
Management District: Agricultural land and water use projections for 1995 and 2010
supplement (Lynne and Kiker 1992) and Needs and sources planning in the St.
Johns River Water Management District: Golf course land and water use projections
for 1995 and 2010 (Lynne 1992).

Other water use categories, including commercial/industrial self-supply,
domestic self-supply, and power generation self-supply, are anticipated to
experience increases during the 20-year period from 1990 to 2010. However,
these increases are not expected to significantly impact the water resources of
SJRWMD and, therefore, have not been included in the ground water and
surface water evaluations. It may be necessary to re-evaluate the use of water
use projections for these categories if projections for these categories change
significantly.

A summary of 1990 water use data and projected 2010 water use data, utilized
in the water resource assessment process, is presented in Table 1. A
substantial disparity exists between the projected 1990 to 2010 water use
growth estimates and the projected population growth estimates for the same
period. SJRWMD plans to resolve this discrepancy during the working group
sessions planned for major water users in 1993.

Table 2 provides current and projected public supply water use quantities for
each county or part of a county within the SJRWMD. This table shows where
the greatest amounts of increased public supply water use are expected.
Increases in public supply use are expected to account for most of the growth
in water demand through the year 2010. Existing urban areas are expected to
account for the greatest part of this increase. Public supply water use is
projected to increase by about 121 percent during the period between 1990 and
2010. Counties which are projected to experience water use increases












Public Supply and Agricultural Water Use (in million gallons per day) for 1990
and 2010, St. Johns River Water Management District


Year County Public Supply Agricultural
Ground Surface Total Ground Surface Total
1990 Alachua 20.97 0.00 20.97 9.42 0.18 9.60
Baker 0.81 0.00 0.81 3.30 2.20 5.50
Bradford 0.16 0.00 0.16 0.12 0.00 0.12
Brevardb 11.55 16.24 27.79 100.78 10.40 111.18
Clay 11.11 0.00 11.11 3.00 0.44 3.44
Duval 96.32 0.00 96.32 9.53 1.40 10.93
Flagler 3.85 0.00 3.85 7.50 1.20 8.70
Indian River 13.17 0.00 13.17 50.84 117.73 168.57
Lake 20.67 0.00 20.67 43.66 12.63 56.29
Marion 11.56 0.00 11.56 9.66 1.39 11.05.
Nassau 3.85 0.00 3.85 2.40 0.60 3.00
Okeechobee 0.00 0.00 0.00 9.78 0.25 10.03
Orange' 127.28 0.00 127.28 24.44 60.03 84.47
Osceola 0.00 0.00 0.00 6.05 8.09 14.14
Polk 0.06 0.00 0.06 3.66 0.35 4.01
Putnam 3.15 0.00 3.15 20.48 1.35 21.83
St. Johns 8.39 0.00 8.39 40.54 1.39 41.93
Seminole 50.79 0.00 50.79 11.19 1.80 12.99
Volusia 44.21 0.00 44.21 23.03 4.50 27.53
Totals 427.90 16.24 444.14 379.38 225.93 605.31

2010 Alachua 27.70 0.00 27.70 9.24 0.18 9.42
Baker' 1.02 0.00 1.02 3.30 2.20 5.51
Bradford' 0.16 0.00 0.16 0.12 0.00 0.12
Brevard' 25.80 22.94 48.74 105.32 10.87 116.19
Clay 20.96 0.00 20.96 3.15 0.46 3.61
Duval 206.34 0.00 206.34 9.93 1.46 11.39
Flagler 6.80 0.00 6.80 7.52 1.20 8.72
Indian River 40.50 0.00 40.50 50.58 117.12 167.70
Lake 65.83 0.00 65.83 60.90 17.62 78.52
Marion 16.00 0.00 16.00 13.17 1.90 15.07
Nassau 6.83 0.00 6.83 2.40 0.60 3.00
Okeechobee 0.00 0.00 0.00 9.78 0.25 10.03
Orange 312.09 0.00 312.09 27.28 67.01 94.30
Osceola' 0.00 14.20 14.20 6.45 8.62 15.07
Polk 0.06 0.00 0.06 4.75 0.45 5.20


Table 1.










Table 1. Continued


Year County Public Supply Agncultural'
Ground Surface Total Ground Surface Total
2010 Putnam 4.60 0.00 4.60 20.52 1.35 21.87
continued St. Johns 23.86 0.00 23.86 40.62 1.39 42.01

Seminole 99.50 0.00 99.50 9.87 1.59 11.45
Volusia 87.93 0.00 87.93 23.90 4.67 28.57
Totals 945.98 37.14 983.12 408.81 238.95 647.76

* Agriculture includes golf courses.
b Does NOT include 23.52 mgd (in 1990) & 27.81 mgd (in 2010) of water withdrawn in Orange County for
public supply use in Brevard County.
C DOES include 23.52 mgd (in 1990) & 27.81 mgd (in 2010) of water withdrawn in Orange County for
public supply use in Brevard County.
d Water use projections for Baker & Putnam Counties from Kimball-Uoyd 1991.
* Public supply water use projections for Bradford & Polk Counties are estimated (Florence pers, com.
1992).
' Does NOT include projected 14.20 mgd of surface water withdrawn in Osceola County for public supply
use in Brevard County.
g DOES include projected 14.20 mgd of surface water withdrawn in Osceola County for public supply use
in Brevard County.

Source: Florence 1992 draft











Change in Public Supply Water Use from 1990 to 2010 in the St. Johns River
Water Management District (in million gallons per day)


County Year Percent
Change
1990 2010 Change

Alachua 20.97 27.70 32.1

Baker 0.81 1.02 25.9
Bradford 0.16 0.16 0.0
Brevard 27.79 48.74 75.4
Clay 11.11 20.96 88.7
Duval 96.32 206.34 114.2

Flagler 3.85 6.80 76.6
Indian River 13.17 40.50 207.5
Lake 20.67 65.83 218.5
Marion 11.56 16.00 38.4
Nassau 3.85 6.83 77.4
Okeechobee 0.00 0.00 0.0
Orange 127.28 312.09 145.2
Osceola 0.00 14.20 NA

Polk 0.06 0.06 0.0

Putnam 3.15 4.60 46.0

St. Johns 8.39 23.86 184.4

Seminole 50.79 99.50 95.9

Volusia 44.21 87.93 98.9

Totals 444.14 983.12 121.4


Source: Florence 1992 draft


Table 2.







exceeding 100 percent during this period are Lake County (218 percent), Indian
River County (208 percent), St. Johns County (184 percent), Orange County
(145 percent), and Duval County (114 percent). Orange County is projected to
need the largest increase in public supply water use by 2010 (312.09 mgd).

GROUND WATER AND SURFACE WATER MODEL DEVELOPMENT

Ground Water

Overview of Resources within the SJRWMD

Three aquifer systems supply ground water in the SJRWMD: the surficial, the
intermediate, and the Floridan (Figure 1). The hydrogeologic nature of these
aquifers is described in Hydrogeological units of Florida (Southeastern Geological
Society 1986).

Surficial Aquifer System. The surficial aquifer system is composed primarily
of sand and sandy clay and is located from land surface downward to the top
of the confining unit of the intermediate aquifer system, where present, or to
the top of the confining unit of the Floridan aquifer system where there is no
intermediate aquifer system, or to the top of the Floridan aquifer where there
is no confining unit. The surficial aquifer system contains the water table,
which is the top of the saturated zone within the aquifer. Water within the
surficial aquifer system occurs mainly under unconfined conditions, but beds
of low permeability cause semi-confined or locally confined conditions to
prevail in its deeper parts.

Water quality in the surficial aquifer system is generally good. Chloride,
sulfate, and total dissolved solids concentrations are below the secondary
drinking water standards of 250, 250, and 500 mg/L, respectively. Iron
concentrations, however, are generally high and in many places exceed the
secondary drinking water standard of .3 mg/L. In coastal areas, such as the
barrier islands, this aquifer is prone to saltwater intrusion.

The surficial aquifer is a source of public water supply in St. Johns, Flagler,
Brevard, and Indian River counties. It is also used as a source of individual
domestic self-supply mainly along the coastal portions of the SJRWMD, but
also in inland areas scattered throughout the SJRWMD.






ED SAND
C CLAY
t LIMESTONE
1 SHELL







..;..i.':.SURFICIAL AQUIFER. .
,' ." .. : :" '" ': .; '" ". ". "." '.: '." ". ", : '. : '.; '.; ". .; '.J ^ ^ ______A tla n tic O c e an'" .
'" i2))..Atlantic Ocean
................

... . .9
...II-... .. .r -.T .. ,. -*-,._ -, *. --- -. -- ._ ^- -.---. ^--,--.- z .-:z .- j_ -. ^ -, ._, -.. ._.
.--" I :'NTERMEDIATE AQUIFER :--. ...:--C:. f -:
.. -- . ... . .





-UFLORIDAN AQUIFER





Figure 1. Generalized east-west hydrogeologic cross-section of the St. Johns River Water Management District









Intermediate Aquifer System. The intermediate aquifer system is composed
of thin water bearing zones of sand, shell, and limestone which lie within or
between less permeable units of clayey sand to clay. In places, poorly yielding
to non-water-yielding strata occur, and there the term intermediate confining
unit applies. This intermediate confining unit is geologically referred to as the
Hawthorn Group of Miocene Age. In other places, one or more low- to
moderate-yielding aquifers may be inter-layered with relatively impermeable
confining beds. There the term intermediate aquifer system applies. The aquifers
within this system contain water under confined conditions.

The top of the intermediate aquifer system or intermediate confining unit
coincides with the base of the surficial aquifer system. The base of the
intermediate aquifer or intermediate confining unit lies immediately above the
Floridan aquifer system.

Water quality in the intermediate aquifer system is generally good in the
northern part of the SJRWMD where chloride, sulfate, and total dissolved
solids concentrations are below the secondary drinking water standards.
Water quality in the southern part of the SJRWMD approaches or exceeds the
secondary drinking water standards for chloride and total dissolved solids
concentration.

The intermediate aquifer system is used as a source for individual domestic
water supply in Duval and Clay counties.

Floridan Aquifer System. The Floridan aquifer system is one of the world's
most productive aquifers. The sediments that comprise the aquifer system
underlie the entire state although this aquifer does not contain potable water at
all locations. The Floridan aquifer is generally composed of limestone and
dolomite. Water in the Floridan aquifer system occurs under confined
conditions throughout most of the SJRWMD. Unconfined conditions occur in
parts of Alachua and Marion counties.

Water quality in the Floridan aquifer system is good in the northern and
western portions of the SJRWMD where chloride, sulfate, and total dissolved
solids concentrations are below the secondary drinking water standards.
Chloride and total dissolved solids concentrations in the Upper Floridan
aquifer generally exceed the secondary drinking water standards throughout
most of Brevard and Indian River counties, in areas bordering the St. Johns
River south of Palatka, in Putnam, Marion, Lake, Volusia, Seminole, Orange,
and Osceola counties, and in eastern Volusia County. Sulfate concentrations










also often exceed the secondary drinking water standard. Areas where
concentrations of chlorides, sulfates, and total dissolved solids exceed
secondary drinking water standards in the Upper Floridan aquifer are shown
in Figure 2.

The Floridan aquifer system is a source of public water supply in the northern
and central portions of the SJRWMD where the aquifer contains potable water.
The Floridan aquifer system is also a source for public water supply in the
southern portion of the SJRWMD where water withdrawn from the aquifer is
treated by reverse osmosis.

Methods

Ground water flow and water quality models will serve as primary tools for
assessing the impacts of water resource development projected to occur-by the
year 2010.

Numerical ground water flow models have been developed, and additional
models are scheduled for development, to provide the tools necessary to
project estimated ground water levels which will exist in 2010. These flow
models were developed on regional scales for areas which have experienced or
are expected to experience significant ground water development during the
next 20 years. The models were calibrated to steady-state conditions. The
names of these models, the areas included within each model's boundaries,
and the source of information for each model are listed in Table 3. The
locations of these model areas are shown in Figure 3. Development of a
numerical ground water flow model for the north-central area of the District is
scheduled for completion in 1993.

In addition to evaluations using these regional models, analytical modeling
techniques have been used to evaluate proposed withdrawals from several
public supply wellfields as follows.

S City of Gainesville (Fischl 1992b)
S City of Leesburg (Szell 1992b)
S St. Johns County (Toth 1992b)
S City of St. Augustine (Toth 1992a)
S Palm Coast Utilities (Szell 1992a)
S City of Vero Beach (Toth 1992c)
Indian River County (Toth 1992c)
S City of Ocala (Fischl 1992a)






















Shaded areas represent locations where the Upper Floridan aquifer
contains concentrations of chlorides, sulfates, and total dissolved
solids which exceed the US Enviromental Protection Agency's
recommended drinking water standards of 250mg/I, 250mg/I, and
500 mg/I respectively as modified from Sprinkle (1982 a,b,c),
Tibbals (1990), Speckler and Hampson (1984), and Toth (1990).


1POLK


Figure 2
Areas where concentrations of chlorides, sulfates,
and total dissolved solids exceed secondary drinking
water standards in the Upper Floridan aquifer.


SJRWMD 1992


1o 0 10 20 30
APPROXIMATE SCALE IN MILES











Table 3.


Regional ground water flow model summary


Model Name CoumytAreas Covered Within Title of Related Publication SJRWMD
Model Boundaries Publication
Number
1 FLORIDAN AQUIFER SYSTEM
Northeast Portions of Nassau, Duval, Finite-difference simulation of Pending
Florida Regional St. Johns, and Clay counties, "the Floridan aquifer system in
Ground Water Florida, and Camden County coastal northeast Florida and
Flow Model Georgia Camden County, Georgia
(Durden draft 1992)
Volusia Regional Portions of Volusia, Flagler, Numerical modeling of SJ92-SP6
Ground Water Putnam, Seminole, and Lake ground-water flow and sea
Flow Model counties water intrusion, Volusia
County, Florida (Geraghty &
Miller 1991)
Volusia Regional Portions of Volusia, Flagler, Revision and recalibration of Pending
Ground Water Putnam, Seminole and Lake a regional flow model of the
Flow Model counties Volusia ground water basin
(revised) (Williams draft 1992a)
West All of Flagler County and Ground water resource Pending
Volusia/Southea portions of Putnam, Volusia, evaluation of the Floridan
st Putnam Flagler, Lake, Seminole, and aquifer system in western
Regional St. Johns counties Volusia and southeastern
Ground Water Putnam counties, Florida
Flow Model (McGurk draft 1992)
Wekiva All of Seminole County and Wekiva River basin ground SJ92-SP19
Regional portions of Lake, Orange, water flow and solute
Ground Water Volusia and Polk counties transport modeling study:
Flow Model Phase I: Regional ground
water flow model
development (GeoTrans, Inc.
1992)

Wekiva All of Seminole County and Revised spring conductance Pending
Regional portions of Lake, Orange, parameters for the Wekiva
Ground Water Volusia, and Polk counties River basin model (Huang
Flow Model draft 1992)
(revised)
East-Central All of Orange and Seminole Regional ground water flow SJ92-SP17
Florida Regional Counties, and portions of modeling for east-central
Ground Water Brevard, Osceola, Orange, Florida with emphasis on
Flow Model Lake, Volusia, and Polk Orange and Seminole
counties counties (Blandford and Birdie
1992)











Table 3. Continued


Model Name County/Areas Covered Within Title of Related Publication SJRWMD
Model Boundaries Publication
Number
Titusville/Mims Northern Brevard County Development and application Pending
Regional of a regional ground water
Ground Water flow model of the surficial
Flow Model aquifer system in the
Titusville/Mims area of
Brevard County, Florida
(Williams Draft 1992b)
SURFICIAL AQUIFER SYSTEM
Titusville/Mims Northern Brevard County Development and application Pending
Regional of a regional ground water
Ground Water flow model of the surficial
Flow Model aquifer system in the
Titusville/Mims area of
Brevard County, Florida
(Williams Draft 1992b)












NORTHEAST FLORIDA REGIONAL
GROUND WATER FLOW MODEL

SVOLUSIA REGIONAL
GROUND WATER FLOW MODEL

Li WEST VOLUSIASOUTHEAST PUTNAM
REGIONAL GROUND WATER FLOW MODEL

WEKIVA REGIONAL GROUND WATER
FOD C FLOW MODEL

EAST CENTRAL FLORIDA REGIONAL
GROUND WATER FLOW MODEL
i PURrNAM
STITUSVILLE/MIMS REGIONAL GROUND
WATER FLOW MODEL


Figure 3

Regional ground water flow model areas,
St. Johns River Water Management District


SCALE: 1 inch 34 miles








Ground water quality modeling is scheduled for those areas of the SJRWMD
where proposed ground water withdrawals from the aquifer are projected to
have significant impacts on the potentiometric surface of the Florida aquifer in
association with the location of saline water in the Upper Floridan aquifer and
where strong potential exists for proposed withdrawals from the surficial
aquifer to result in noticeable increases in chloride concentrations in the
surficial aquifer.

These areas are as follows.

S City of Jacksonville
S City of Fernandina Beach
S Wekiva River Basin
S Eastern Orange County
S Volusia County
S Northwest Volusia/southeast Putnam counties
Seminole County
S Titusville/Mims

These water quality models will provide tools to make reasonable estimates of
chloride concentrations in ground water which will result from proposed 2010
withdrawals. These models are scheduled to be completed in 1993.

Surface Water

Overview of Resources within the SJRWMD

Streams, lakes, canals, and other surface water bodies in the SJRWMD provide
both saline and fresh water for various consumptive and non-consumptive
uses. Although aquifers usually contain relatively high quality water and are
likely to remain the most widely used fresh water supply sources in the
SJRWMD, pressure to develop surface water sources could increase as ground
water becomes less available. If environmentally and economically feasible,
additional surface water could be made available for future use.

Water quality can limit water availability in a surface water body if it is not
economically feasible to treat the water to the level required for the intended
use. Surface water quality in the SJRWMD varies both spatially and
temporally due to natural processes and human activities that affect the
chemical and microbiological character of waterbodies. The linkage between
water quality and water availability is determined by the quality requirements









for different intended uses. For example, some industrial uses can tolerate
total dissolved solids concentrations of 35,000 mg/L (equivalent to sea water),
whereas a maximum of 500 mg/L is recommended for public supply (Prasifka
1988).

Compared to most groundwater sources in the SJRWMD, surface water
sources generally are of lower quality. Surface waters tend to contain silts and
suspended sediments, dissolved organic matter from top soil, and chemical
and microbiological contaminants from municipal wastewater discharges,
stormwater runoff, and industrial and agricultural activities. The quality of
surface water may vary seasonally with variation in flow rates or water levels.

Salinity is one of the most important water quality considerations in the
SJRWMD. In the coastal rivers of the SJRWMD and the tidal reaches of the
St. Johns, St. Marys, and Nassau rivers, the influx of seawater limits potential
water uses to recreation and power plant cooling. Chloride concentrations
generally decrease upstream from the mouths of these rivers as tidal influence
diminishes. In addition to the influence of tides, inflows of saline ground
water and fresh surface or ground water affect the spatial distribution, of
chloride concentration. Water quality may limit water availability in some
reaches of the St. Johns River because of the cost of treating saline water to the
degree necessary for most agricultural and public supply uses.

In addition to the influence of tides, inflows of saline ground water and
inflows of fresh water affect the spatial distribution of chloride concentrations
in the St. Johns River. During low flow periods when there is little dilution
from fresh water inflows, high chloride concentrations occur in the tidally
influenced lower reach of the river and in an upper reach between Lakes
Harney and Poinsett. The high chloride concentrations in the upper reach are
due to inflows of saline ground water. Water quality may limit water
availability in some reaches of the St. Johns River because of the cost of
treating saline water to the degree necessary for most agricultural and public
supply needs.

Water Availability from Streams. Monthly discharges generally reflect the
seasonal distribution of annual rainfall. Streams in the SJRWMD usually
exhibit at least two high and low flow seasons over the course of the year.
The highest average monthly discharges tend to occur in August, September,
and October, when summer thunderstorms are common and tropical storms
are most likely to occur. More importantly, the lowest average monthly
discharges tend to occur during the late fall to early winter (November and








December) months and the late spring to early summer (May and June)
months. Because some of the highest demands for surface water occur during
these periods, temporal fluctuations of water supply do not coincide with
fluctuations in water demand. High irrigation water demands often occur
during May and June, and December, which is the beginning of the season for
frost and freeze protection. Monthly time increments are convenient for water
supply assessments because, although withdrawals from a water body are
often made on a continuous or daily basis, withdrawal data are often reported
on a monthly basis.

Water Availability from Lakes. Most of the larger lakes in the SJRWMD are
part of the Ocklawaha or St. Johns rivers, and their quality and stage
fluctuations are similar to that of the rivers of which they are a part. Water
quality problems currently limit water availability in the Upper Ocklawaha
chain of lakes, including Lakes Apopka, Harris, Eustis, Griffin, Dora, and
others. Major lakes of the St. Johns River system include Lakes George,
Harney, Monroe, Jesup, Poinsett, and Washington and Crescent Lake. Other
major lakes, including Newnans, Lochloosa, and Orange lakes, are located in
the Florida Ridge and Orange Lake Basin. U.S. Geological Survey (USGS) lake
stage records could be data sources for future investigations of lake water
availability. Lake stage data are also collected by the SJRWMD, but periods of
record are considerably shorter.

Methods

Estimating the quantity of water available in a surface water body requires
analyses of the hydrologic, water quality, economic, and environmental
constraints associated with the use of the water. SJRWMD staff is
investigating the environmental and hydrologic feasibility of surface water
withdrawals under the Minimum Flows and Levels Program. This program
involves detailed hydrologic and ecological evaluations for individual
waterbodies, with a methodology that incorporates water requirements for fish,
riparian habitat, floodplains, and channel morphology. Under this program,
the establishment of minimum flows and levels on individual waterbodies may
place environmental constraints on future withdrawals of surface water.

Future assessments of surface water availability will require the application of
continuous hydrologic simulation models. To properly evaluate the impact of
a proposed withdrawal from a given waterbody, it is necessary to have a
means of examining the response of the hyudrologic system to rainfall and
other random variables. Simulation models provide the most logical and





scientifically advanced means of predicting a system's response under various
rainfall conditions, basin conditions, and water use situations. Once a set of
minimum flows or levels are established for a waterbody, the simulation
models can be used to evaluate the potential impact of a proposed withdrawal
on the hydrologic system.

Streams. USGS Water Resources Data for Northeast Florida, published on a water
year basis (October through September) for all active surface water gauges, are
the most comprehensive sets of surface water stage and discharge data
available for waterbodies in the SJRWMD. As of water year 1990 (USGS 1991),
84 stream gauge, 16 canal gauges, and 48 lake gauges were active in the
SJRWMD.

Using available discharge data, this assessment identifies gauged stream sites
where substantial quantities of water are likely to be available throughout the
year. With the rare exception of streams with very stable base-flows resulting
from constant ground water discharge, most streams in the SJRWMD would
require artificial storage for an assured supply of water. If the pressure to
withdraw water from surface water bodies becomes significant, the feasibility
of providing storage may need to be incorporated into water availability
assessments.

Low-flow information from flow duration analysis is useful for estimating
water availability during the driest conditions when water demands are
usually highest. An examination of the low-flow end of flow duration curves
for all USGS-gauged sites in the SJRWMD provides a means of screening out
sites with relatively low water supply potential. For purposes of this
assessment, a site is considered to have high water supply potential if all
average daily discharges of record equal or exceed 10 cfs (cubic feet per
second). Discharges below this are not considered to be feasible for
development as water supplies. Sites meeting the 10 cfs requirement are listed
in Table 4.

The sites listed in Table 4 are considered to have relatively high potential for
water supply development, solely on the basis of their low-flow characteristics.
For purposes of this preliminary assessment, this is a reasonable starting point.
However, several important caveats are noteworthy. Inclusion of a site in
Table 4 does not necessarily mean that the site is economically, technically, or
environmentally feasible to develop as a water-supply source. Sites listed in
Table 4 are identified as potential supply sources, which could be investigated
further if additional supplies are needed in their vicinities. Further











Table 4.


Gauged stream sites in the St. Johns River Water Management District with
daily discharges of record exceeding 10 cubic feet per second 100 percent of
the time.


SJRWMD USGS' USGS Gauging Station Period of Number Average
Subbasin Station Name Record of Discharge
Number Number Years "

2-001 02231000 St. Marys River, near 1927-90 64 663
Macclenny
3-200 02245050 Etonia Creek, at Bardin 1974-90 17 96
3-200 02245500 South Fork of Black Creek, 1940-90 51 153
near Penney Farms
4-202 02235000 Wekiva River, near Sanford 1936-90 55 285
4-401 02234000 St. Johns River, above Lake 1982-90 9 1,606
Harney
5-002 02236000 St. Johns River, near 1934-90 57 3,043
De Land
6-201 02232400 St. Johns River, near Cocoa 1954-90 37 955
7-402 02239500 Silver Springs, near Ocala 1933-90 58 808
7-402 02240000 Ocklawaha River, near 1931-90 29 1,130
Conner
7-500 02240500 Ocklawaha River, at Eureka 1931-90 22 1,305
8-007 02243960 Ocklawaha River, at 1969-90 22 1,427
Rodman Dam

*USGS = U.S. Geological Survey
"Measured in cubic feet per second


Note: Some years are omitted for some stations because data were missing. Thus, the
number of years is less than indicated by the period of record for some sites.

Source: USGS 1991










investigation will be required to evaluate the feasibility of developing water
supply sources at any of the listed locations.

The 1994 final DWMP will include further analysis of the listed sites, and
possibly gauged or ungauged sites not listed in Table 4, to identify which, if
any, have the potential to be regionally significant water supply sources.
Many of the listed stream segments may be too far from the demand to justify
the cost of constructing pumping, treatment, storage, and transmission
facilities, if less costly alternatives are available. Analysis of the cumulative
impacts of withdrawals at multiple sites may be required to estimate the actual
amount of water available in the stream system. Many stream segments may
be vulnerable to unacceptable environmental impacts. Finally, although some
of the listed sites may be physically capable of providing adequate water,
many may require a supplemental storage facility.

Lakes. Large volumes of water are stored in the many lakes located within
the boundaries of the SJRWMD. Simulation models and other detailed
assessments of water availability in lakes will be conducted on a case by case
basis, as necessary.

IMPACT ASSESSMENT

Ground Water

In areas of the SJRWMD other than the area covered by the Titusville/Mims
Regional Ground Water Flow Model, Table 3 surficiall aquifer), changes in the
elevation of the water table of the surficial aquifer were projected using a
technique described in a SJRWMD technical publication titled Determination of
surficial aquifer drawdown using a coupled analytical and numerical iterative
procedure (Huang, Williams, and Durden 1992 draft). This model was also
used to produce revised 2010 potentiometric surface elevations that are
thought to be more realistic than those produced by the regional flow models.
This is because the regional flow models assume constant water table
elevations, which probably results in underestimations of the drawdown in the
potentiometric surface of the Floridan aquifer.

Projected 2010 water use was used in combination with the regional flow
models and analytical models to produce projected 2010 potentiometric heads
in the Upper Floridan aquifer. The resultant projected heads were refined
using the technique described by Huang, Williams, and Durden (1992 draft).
These, in turn, were combined to produce a map of the projected 2010









potentiometric surface of the Upper Floridan aquifer (Figure 4). Where the
regional flow models overlapped, heads in areas of the regional flow model
considered to be the most accurate were used to produce the final Districtwide
map.

In addition to the map of the 2010 potentiometric surface, a simulated
potentiometric map of the steady-state condition of the Floridan aquifer for
1988 was created for the purpose of comparison (Figure 5). This 1988 map
was developed using the same methodology as that used to produce the map
of the 2010 potentiometric surface.

Based on a comparison of the configuration of the projected 2010
potentiometric surface to the simulated 1988 potentiometric surface, a
predicted change in the potentiometric surface between these two periods was
calculated. Associated with this exercise is the assumption that regional
climatic conditions will be similar in 2010 to those that existed in the years of
model calibration which were characterized by reasonably average climatic
conditions. Evaluation of the resulting change map (Figure 6) indicates that, if
current 2010 water supply plans are carried out, the greatest regional impacts
to the Floridan aquifer will occur in Seminole and Orange counties.

Using the techniques described by Huang, Williams, and Durden (1992 draft),
declines in the surficial aquifer water table were projected for the period 1988
to 2010 (Figure 7). Based on this evaluation, if current 2010 water supply
plans are carried out, the greatest regional impacts to the water table will
occur in Seminole and Orange counties.

Surface Water

Impacts of existing and proposed withdrawals on surface water bodies will be
assessed through the application of hydrologic models. SJRWMD is currently
developing continuous simulation models for the Upper St. Johns and Upper
Ocklawaha river basins. Other simulation models have been developed for the
Wekiva River and several lakes in the SJRWMD. Future modeling efforts will
be guided by priorities established through the Water Supply Needs and
Sources Assessment and the Minimum Flows and Levels Program.






















































Figure 4
Potentiometric surface of the
Upper Floridan Aquifer in 2010


SJRWMD 1992

10 0 10 20 30
APPROXIMATE SCALE IN MILES























































Figure 5
Potentiometric surface of the
Upper Floridan aquifer in 1988


SJRWMD 1992

10 0 10 20 30
APPROXIMATE SCALE IN MILES























SPUTNAM .
J.., A

MARION I







C1 S'






1 POU 1
I a 1


Figure 6
Difference between the simulated 2010 and 1988
potentiometric surfaces of the Upper Floridan aquifer


SJRWMD 1992

10 0 10 20 30
APPROXIIMTE SCALE IN MILES
























-j
K


L


POLK


i1 j
'V


Figure 7
Projected changes in the surficial
aquifer water table between 1988 and 2010


O ]Lower
(Less than or equal to 0.99 feet)

Intermediate
(1.00 Z49 feet)

SHigher
(Greater than or equal to 250 feet)


SJRWMD 1992

0 0 1 0 20 30
APPROXIMATE SCALS IN MILES









IMPACT CRITERIA DEVELOPMENT


Criteria for assessing the acceptability of water resource impacts projected to
occur by 2010 have been developed or are in development for the following
categories.

Vegetation
Ground water quality-saltwater intrusion
Surface water bodies
Existing legal users

Water resource problem areas based on the ground water quality, surface
water bodies, and existing legal users impact criteria will be delineated in 1993.

Conventions committees composed of members of the five Florida water
management districts and the Florida Department of Environmental Regulation
are currently addressing development of such criteria in an effort to assure
reasonable statewide consistency. Because this process is incomplete, the
impact assessment criteria developed arid applied in association with the
SJRWMD 1992 Draft DWMP are those which appear to be consistent with the
directions of the various conventions committees.

Vegetation

An approach for evaluating the potential for harm to vegetation as a result of
declines in the water table has been developed by Kinser and Minno and is
described in a SJRWMD technical publication titled Estimating the likelihood of
harm to native vegetation from ground water withdrawal in the St. Johns River Water
Management District (1992 draft). This approach considers the relative
sensitivity of different vegetative communities to declines in the water table
and provides means by which all areas of the SJRWMD can be characterized as
having lower, moderate, or higher likelihood of harm to vegetation. Locations
of potentially affected plant communities are shown in Figure 8.

Ground Water Quality-Saltwater Intrusion

The potential for heightened concentrations of naturally-occurring chloride,
sulfate, and total dissolved solids in ground water increases with declines in
the potentiometric surface. Impact assessment criteria for saltwater intrusion
will be developed during 1993 in conjunction with development of ground
water quality models.


I






































































Figure 8
Areas of potential impact to plant communities

resulting from projected changes in ground

water withdrawals between 1988 and 2010.


SJRWMD 1992


10 0 10 20 30
APPROXIMATE SCALE IN MILtS


i










Surface Water Bodies


Assessment criteria for ground and surface water withdrawal impacts on
surface water bodies such as lakes, streams, and estuaries will be developed
during 1993 and will be applied in the areas of spring runs of major springs in
the SJRWMD.

Existing Legal Users

Criteria for assessing the impact of proposed 2010 ground water withdrawals
on existing legal users will be developed and applied during 1993.

DELINEATION OF WATER RESOURCE PROBLEM AREAS

Subsection 17-40.501(1), F.A.C., requires that "specific geographical areas that
have water resource problems which have become critical or are anticipated to
become critical within the next 20 years" be identified. SJRWMD will identify
these areas based on the acceptability of the ground and surface water impacts
of current and projected water use. This will be accomplished by comparison
of the projected impacts to the impact criteria.

At the present time, SJRWMD has completed development of impact criteria
for vegetation, but not for the other three impact criteria categories (ground
water quality, surface water bodies, and existing legal users). Based on the
evaluation performed and reported on by Kinser et al. (1992 draft), several
areas of the SJRWMD may experience impacts to vegetation as a result of
proposed future ground water withdrawals. The potential for these impacts is
illustrated in Figure 8. Potential water resource problem areas based on the
vegetation impact criteria include the areas with the greatest concentrations of
intermediate and/or higher potential for impact to plant communities as
illustrated in Figure 8 and the public supply service areas associated with the
ground water withdrawals in these areas. Relatively small, isolated areas with
intermediate and/or higher potential, which are dissociated from the areas
with the greatest concentrations of intermediate and/or higher potential, are
not considered significant to this evaluation.

Water resource problem areas based on other impact criteria will be delineated
in 1993.









WATER SUPPLY ALTERNATIVES

Following delineation of water resource problem areas, SJRWMD will work
with local governments, private and public water suppliers, and interested
groups within the identified water resource problem areas to define possible
alternative water supply scenarios which represent preventive courses of
action. These alternative scenarios may include a variety of supply
enhancement and demand management options such as improved water
conservation, reuse of reclaimed water, and relocation of proposed
withdrawals. Through coordination with these water resource problem area
working groups, SJRWMD staff will attempt to identify alternative water
supply scenarios which will prevent unacceptable impacts to ground and
surface water systems.

SUPPLY ENHANCEMENT

The following are some of the options which may be considered in
development of alternative water supply scenarios.

Reuse
Recirculation
Matching water quality with use
Improved efficiency
Membrane treatment
Expanded storage
Development of new source locations

Reuse

Both wastewater and stormwater can be reused. The use of reclaimed
wastewater for non-potable uses, such as golf course, landscape, crop
irrigation, and freeze protection has been encouraged. This practice makes
additional water available without placing further burden on ground and
surface water supplies. Stormwater might be used for golf course irrigation
and landscaping.

Recirculation

Recirculation is distinct from reuse in that the water is used again for its
original purpose. Recirculated water may be used repeatedly or continuously
with only make-up water added. Many industrial and commercial water users









already have implemented recirculation efforts in response to environmental
regulations.

Matching Water Quality with Use

Some uses require high quality water while lower quality water is suitable for
others. Matching appropriate quality for the use would conserve higher
quality water for uses where it is needed,

Improved Efficiency

The initial step toward enhancing operational efficiency is a water audit. The
audit may be used to identify and quantify how much water passes through
the system and where it goes.

Membrane Treatment

Membrane treatment and similar technologies may be applied to make lower
quality water suitable for potable uses. These methods are usually associated
with the removal of chlorides but may also be used to remove other
impurities. Improvements in technology involving low pressure reverse
osmosis and ultrafiltration membranes have reduced operating costs
substantially for newer systems.

Expanded Storage

Natural systems provide storage of water collected during the wet season for
later use. Expanded storage can be provided by traditional tanks, aquifer
storage and recovery, and offstream reservoirs.

Development of New Source Locations

New source locations are becoming more scarce, yet they are still available.
Many of the less costly sites to develop have already been used. New source
development often requires transportation of water from greater distances or
more expensive treatment. Ground water currently is the supply source for 70
percent of the SJRWMD total fresh water use, including 62 percent of
agricultural and 96 percent of public supply (Florence 1992 draft). Some high
quality ground water sources are still available. Often, however, these are
found at increasing distances from public supply demand centers. Surface
water is the supply source for 38 percent of the SJRWMD's agricultural water









use and 96 percent of the fresh water used for power generation (Florence 1992
draft). New surface water sources may become increasingly important as
ground water sources become more difficult to develop.

DEMAND MANAGEMENT

The following are some of the options which may be considered in
development of alternative water supply scenarios.

Conservation
Regulations

Conservation

Conservation programs endeavor to influence water users to use water more
efficiently, and thereby reduce withdrawal. This can be accomplished through
consumer education and economic incentives such as metering, pricing
policies, taxes, surcharges, impact fees, and connection fees.

Regulations

Regulations can be indirect or direct with regard to influencing water users to
adopt efficient water use practices. Indirect regulatory options involve the use
of laws and regulations, such as plumbing codes; landscape codes; landscape
irrigation regulations; land use planning, zoning and subdivision regulations;
retrofit devices and consumer leak detection; and irrigation standards. Direct
regulations utilize legal means to limit the amount of water used. These may
be implemented through such means as consumptive use permit conditions,
ongoing water conservation requirements, or temporary restrictions during
water shortages.


WATER MANAGEMENT STRATEGIES

Detailed policy statements will be presented in the final DWMP in 1994.
Analysis of additional information to be derived from projects currently in
progress is needed before policies can be finalized for aligning supply and
demand.

Overall, SJRWMD will work with major water users located in potential water
resource problem areas to develop solutions in a pro-active manner. In








addition, the consumptive use permitting process will continue to be the
primary tool for managing water needs and sources.

F(PLCY FRAtMEWORK

Much of the authority and responsibility of the water management districts
pertains to assuring the availability of adequate water supplies to meet needs.
Such provisions appear in the Florida Water Resources Act (Chapter 373,
Florida Statutes) and State Water Policy (Chapter 17-40, F.A.C.). Several of
those provisions require the districts to render assistance to local governments
in planning and providing water supplies. Such provisions mesh with rules
requiring local governments to address water supply in their comprehensive
plans. The Minimum Criteria Rule for Local Government Comprehensive
Plans includes several provisions for assuring water supply services
(Subsection 9J-5.011(2), F.A.C.). These rules require Local Government
Comprehensive Plans to include provisions for potable water facilities, water
conservation, and protection of water supply sources.

GUIDING PRINCIPLES

Working principles central to the Water Supply Needs and Sources Assessment
currently in practice include the following.

SJRWMD will work with major water users to identify solutions
to anticipated water supply problems.
Consumptive use permitting will serve as the tool for allocating
water supplies.
Water conservation and reuse will be required to the extent that
they are environmentally, technically, and economically feasible.
Water supply needs projections will be based on projections
made by water users where possible.
Choices of alternatives for future water supplies will be left to
water users except to the extent that the overriding public interest
dictates otherwise.
Consumptive use permittees will be required to monitor and
report water use.

IMPLEMENTATION

Preliminary results of the ground water flow models reported in this plan will
be the basis for forming a series of working groups within areas anticipated to









have inadequate supplies of ground water to meet projected needs. Through
this outreach mechanism, preventive solutions will be sought. Meanwhile,
ground water solute transport models will continue to be developed through
1993 to evaluate the impact of projected needs on saltwater intrusion. Model
results will be integrated into the working group process. During the planning
period, SJRWMD will work with local governments, regional planning
councils, and other interested parties to explore ways to incorporate the results
of the Water Supply Needs and Sources Assessment into the DWMP and local
government comprehensive plans.

SJRWMD will continue to implement the following programs in an effort to
achieve adequate supplies of water.

Consumptive use permitting
Water shortage monitoring and implementation
Data collection (water use, ground water levels, and quality)
Water well and MSSW (Management and Storage of Surface
Waters) permitting
S Minimum flows and levels
S Abandoned artesian well plugging program
S Technical assistance to local governments


LITERATURE CITED

Blandford, T.N. and T. Birdie. 1992. Regional ground-water flow modeling for
east-central Florida with emphasis on Orange and Seminole counties. Special
Publication SJ92-SP17. Palatka, Fla.: St. Johns River Water Management
District.

Durden, D.D. 1992. Finite-difference simulation of the Floridan aquifer system in
coastal northeast Florida and Camden County, Georgia. Draft. Palatka, Fla.:
St. Johns River Water Management District.

Fischl, P. 1992a. Projected 2010 drawdowns in the surficial and Floridan aquifers at
the City of Ocala wellfield, Marion County, Florida. Draft. Palatka, Fla.: St.
Johns River Water Management District.

1 992b. Projected 2010 drawdowns in the surficial and Floridan aquifers at
the Gainesville Regional Utilities' Murphree Wellfield, Alachua County,
Florida. Draft. Palatka, Fla.: St. Johns River Water Management District.









Florence, B.L. 1992. Annual water use survey: 1990. Draft. Palatka, Fla.:
St. Johns River Water Management District.

Geraghty & Miller. 1991. Numerical modeling of ground-water flow and seawater
intrusion, Volusia County, Florida: Volume II. Special Publication SJ92-SP6.
Palatka, Fla.: St. Johns River Water Management District.

GeoTrans, Inc. 1992. Wekiva River Basin groundwater flow and solute transport
modeling study: Phase I: Regional groundwater flow model development.
Special Publication SJ92-SP19. Palatka, Fla.: St. Johns River Water
Management District.

Huang, C. 1992. Revised spring conductance parameters for the Wekiva River Basin
model. Draft. Palatka, Fla.: St. Johns River Water Management District.

Huang, C., S. Williams, and D. Durden. 1992. Determination of surficial aquifer
drawdown using a coupled analytical and numerical iterative procedure.
Draft. Palatka, Fla.: St. Johns River Water Management District.

Kimball-Lloyd, Inc. 1991. Delineation of public water supply service areas and
wastewater treatment plants for St. Johns River Water Management District:
water use projections. Vero Beach, Fla.

Kinser, P. and M. Minno. 1992. Estimating the likelihood of harm to native
vegetation from ground water withdrawal in the St. Johns River Water
Management District. Draft. Palatka, Fla.: St. Johns River Water
Management District.

Lynne, G.D. 1992. Needs and sources planning in the St. Johns River Water
Management District: Golf course land and water use projections for 1995
and 2010. Special Publication SJ92-SP3. Palatka, Fla.: St. Johns River
Water Management District.

Lynne, G.D. and C.F. Kiker, ed. 1992. Needs and sources planning in the
St. Johns River Water Management District: Agricultural land and water use
projections for 1995 and 2010: Supplement. Special Publication SJ92-SP2.
Palatka, Fla.: St. Johns River Water Management District.

McGurk, B. 1992. Ground water resource evaluation of the Floridan aquifer system
in western Volusia and southeastern Putnam counties, Florida. Draft.
Palatka, Fla.: St. Johns River Water Management District.




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