Item 12 Natural Groundwater AquiferMonroe County Comprehensive Plan Update
NATURAL GROUNDWATER AQUIFER RECHARGE ELEMENT
Table of Contents
Item Page
12.0. NATURAL GROUNDWATER AQUIFER RECHARGE ELEMENT................................................1
12.1
Introduction..................................................................................................................................1
12.2
Geology...........................................................................................................................................1
12.3
Hydrogeology...............................................................................................................................2
12.4
Freshwater Lenses..................................................................................................................... 4
12.4.1 Freshwater Lenses on Big Pine Key.....................................................6................ 5
12.4.2 Freshwater Lenses on Sugarloaf Key and Little Torch Key ......................... 7
12.5
Biscayne Aquifer......................................................................................................................... 7
12.6
Floridan Aquifer........................................................................................................................18
12.7
Regulatory Framework..........................................................................................................19
12.7.1 Federal Regulations.................................................................................................19
12.7.2 State Regulations......................................................................................................19
12.7.3 Local regulations......................................................................................................21
12.7.4 Wellfield Protection................................................................................................21
12.7.5 Freshwater Lens Resources.................................................................................23
12.7.6 Water Conservation................................................................................................23
List of Figures
Figure
Paze
Figure 12.1: Map of Freshwater Lens on Big Pine Key........................................................................ 6
Figure 12.2: Map of the Biscayne Aquifer................................................................................................ 8
Figure 12.3: Map of Aquifer Recharge Areas for the Biscayne Aquifer......................................14
List of Tables
Table page
Table 12.1: Groundwater Systems in Monroe County....................................................................... 3
Table 12.2: Water Use Permits Issued by SFWMD for Monroe County....................................10
Natural Groundwater Aquifer Recharge i Technical Document: May 2011
TABLE OF CONTENTS
Monroe County Comprehensive Plan Update
12.0 NATURAL GROUNDWATER AQUIFER RECHARGE ELEMENT
[Rule 9J-5.011(1)(g) and (h), F.A.C.]
The Natural Groundwater Aquifer Recharge Element of the Monroe County Comprehensive
Plan addresses the data inventory requirements of Rule 9J-5.005(2) of the Florida
Administrative Code (F.A.C.). The data inventory requirement will support the
development of goals, objectives, policies, and implementation programs for the Natural
Groundwater Aquifer Recharge Element (Rule 9J-5.011, F.A.C.).
The Natural Groundwater Aquifer Recharge Element is a required comprehensive plan
element under Florida's Local Government Comprehensive Planning and Land
Development Regulation Act (Chapter 163, Florida Statutes). The purpose of the element is
to provide for necessary public facilities and services correlated to future land use
projections.
12.1 Introduction
The potable water supply resources used by Monroe County (County), including both the
aquifer system and treatment facilities, are geographically located in Miami -Dade County -
entirely outside of the County's jurisdiction (see Chapter 8.0, Potable Water Element). In the
County, the surficial aquifer is brackish to saline and contains an inadequate quantity of
water for use as a potable water supply. The Florida Keys Aqueduct Authority (FKAA) is the
agency that obtains and distributes potable water in the Keys. Discussions of the potable
water supply, permitting process and water treatment and distribution systems are
presented in Chapter 8.0, Potable Water Element. As a result of the potable water source for
the County being located entirely within Miami -Dade County, aquifer protection related to
the FKAA's Florida City Wellfield is accomplished through the provisions of the Miami -Dade
County Wellfield Ordinance. In the County, groundwater resource protection and
management takes place in the context of the regulation of public and private interests in
relation to wetlands, wildlife, aquifer discharges to surface waters, and other components of
the natural system.
12.2 Geology
Although Mesozoic sediments represent thicknesses well in excess of 10,000 feet, only the
more recent Cenozoic sediments have a direct bearing on aquifers of the Keys. Of these, the
most important are the sediments deposited since Miocene time, including the Miami
Oolite, the Key Largo Limestone, the Tamiami Limestone, the Hawthorne Formation, the
Tampa Limestone, and the Suwannee Limestone.
The Miami Oolite (oolitic facies of the Miami Formation) is found at the land surface from Big
Pine Key to Key West and is an offshore extension of the same formation found in southeast
Florida. It was formed as a shoal deposit in warm shallow seas. Maximum thickness of the
formation is 40 feet with an average of 20 feet in the Keys. It is white to yellow in color and
Natural Groundwater Aquifer Recharge 1 Technical Document: May 2011
Monroe County Comprehensive Plan Update
12.0 NATURAL GROUNDWATER AQUIFER RECHARGE ELEMENT
[Rule 9J-5.011(1)(g) and (h), F.A.C.J
The Natural Groundwater Aquifer Recharge Element of the Monroe County Comprehensive
Plan addresses the data inventory requirements of Rule 9J-5.005(2) of the Florida
Administrative Code (F.A.C.). The data inventory requirement will support the
development of goals, objectives, policies, and implementation programs for the Natural
Groundwater Aquifer Recharge Element (Rule 9J-5.011, F.A.C.).
The Natural Groundwater Aquifer Recharge Element is a required comprehensive plan
element under Florida's Local Government Comprehensive Planning and Land
Development Regulation Act (Chapter 163, Florida Statutes). The purpose of the element is
to provide for necessary public facilities and services correlated to future land use
projections.
12.1 Introduction
The potable water supply resources used by Monroe County (County), including both the
aquifer system and treatment facilities, are geographically located in Miami -Dade County -
entirely outside of the County's jurisdiction (see Chapter 8.0, Potable Water Element). In the
County, the surficial aquifer is brackish to saline and contains an inadequate quantity of
water for use as a potable water supply. The Florida Keys Aqueduct Authority (FKAA) is the
agency that obtains and distributes potable water in the Keys. Discussions of the potable
water supply, permitting process and water treatment and distribution systems are
presented in Chapter 8.0, Potable Water Element. As a result of the potable water source for
the County being located entirely within Miami -Dade County, aquifer protection related to
the FKAA's Florida City Wellfield is accomplished through the provisions of the Miami -Dade
County Wellfield Ordinance. In the County, groundwater resource protection and
management takes place in the context of the regulation of public and private interests in
relation to wetlands, wildlife, aquifer discharges to surface waters, and other components of
the natural system.
12.2 Geology
Although Mesozoic sediments represent thicknesses well in excess of 10,000 feet, only the
more recent Cenozoic sediments have a direct bearing on aquifers of the Keys. Of these, the
most important are the sediments deposited since Miocene time, including the Miami
Oolite, the Key Largo Limestone, the Tamiami Limestone, the Hawthorne Formation, the
Tampa Limestone, and the Suwannee Limestone.
The Miami Oolite (oolitic facies of the Miami Formation) is found at the land surface from Big
Pine Key to Key West and is an offshore extension of the same formation found in southeast
Florida. It was formed as a shoal deposit in warm shallow seas. Maximum thickness of the
formation is 40 feet with an average of 20 feet in the Keys. It is white to yellow in color and
Natural groundwater Aquifer Recharge 1 Technical Document: May 2011
Monroe County Comprehensive Plan U
contains considerable fine to medium quartz sand that fills the solution holes. The Miami
Oolite has many voids, thereby giving it a high porosity. However, there is little
interconnection between the voids, causing it to have low permeability. This formation
overlays the Key Largo Limestone in the southern Keys.
The Key Largo Limestone occurs at land surface from Soldier Key, off Miami, to Bahia Honda.
It occurs as an ancient reef formation deposited during Pleistocene time. It averages 60 feet
in thickness and is approximately 90 miles long at land surface, by 3 miles wide (Parker et al.,
1955). It is composed mainly of corals, amorphous limestone and detritus from wastage of
the reef. The Key Largo Limestone contains cavities which make it very permeable. As a
result, fresh water readily escapes to the sea, and ocean water easily enters the formation.
Hoffineister and Multer (1964) found that the Miami Oolite passes laterally into the Key
Largo Limestone at the southeastern point of Big Pine Key. They also found that the oolite
in the rest of the island is underlain by the Key Largo Formation. The gradational contact
between the Miami Oolite and the Key Largo Limestone in most places in Big Pine Key lies
at a depth of 13 to 20 feet (Hanson, 1980).
The Tamiami Formation underlies the Key Largo Limestone. It is predominantly permeable
sand with limestone lenses. It forms the lower part of the Biscayne Aquifer system, with the
Miami Oolite and Key Largo Limestone forming the upper part.
The Hawthorne Group underlies the Biscayne Aquifer system and generally acts as a
confining layer to the deeper Floridan Aquifer System. It is relatively impermeable and
consists of silt, clayey sand, and sand. It is phosphatic and greenish in color. Beneath Key
Largo, this sequence is approximately 300 feet thick.
Underlying the Hawthorne Group is the Tampa Limestone. This formation consists of
interbedded calcarenite (cemented sand -size grains of calcium carbonate) and calcilutite
(flour -size grains). The calcarenite sequences contain abundant mollusk molds, giving it high
moldic porosity and permeability. The Tampa Limestone is approximately 600 feet thick.
Because of the alternating high and low permeability beds, this formation is considered a
minor water -bearing zone of the Floridan Aquifer.
The Suwannee Limestone is considered a principal artisan water -bearing zone of the
Floridan Aquifer System. It consists of white, finely porous, chalky limestone composed
chiefly of fragmental shells of bryozoa and foraminifera. In Key West, the formation is
approximately 450 feet thick.
12.3 Hydrogeology
Two major groundwater systems underlie the County: the deeper Floridan Aquifer System,
and the shallower Surficial Aquifer System (the upper portion of which contains the Biscayne
Aquifer). Table 12.1 illustrates the relative positions and productivities of these
hydrogeologic units.
Natural Groundwater Aquifer Recharge 2 Technical Document: May 2011
Monroe County Comprehensive Plan Update
Table 12.1- Groundwater Systems in Monroe County
Surficial Aquifer
Biscayne
Largely saline, must be
The Biscayne Aquifer
System
Aquifer
desalinated for potable
is the upper part of
use. No additional
the Surficial Aquifer
withdrawals will be
System and extends
permitted. Vulnerable to
from ground surface
spills and contamination.
to approximately
Small lenses of relatively
100 feet deep. The
fresh water float above the
Surficial Aquifer
saltwater on some of the
System extends to
larger keys.
200 feet.
Intermediate
Hawthorn
Very low permeability,
200 to 900 feet
Confining
Confining Beds
continuing unit for the
Unit
Floridan Aquifer System.
Floridan
Floridan
Wells yield from 75 to
900 to 3500 feet
Aquifer System
Aquifer
1,000 gallons of saline
water per minute.
Requires desalinization for
all uses.
*Depths vary considerably across the County. Depths shown are typical depths in the Upper Keys.
In the Keys, both of these aquifer systems have chloride concentrations which exceed the
drinking water criteria of 250 milligrams per liter. Therefore, in most cases, they could be
used as a potable water source only after utilization of water quality treatment processes
such as desalinization.
In Miami -Dade County, the Biscayne Aquifer (the upper part of the Surficial Aquifer System)
is a major source of potable water and essentially all potable water in the Keys is piped via
aqueduct to the Florida Keys from wellfields in the Biscayne Aquifer in Miami -Dade County
(see Chapter 8.0, Potable Water Element). Some County residents provide their own water
supply using home reverse osmosis plants to desalinate Biscayne Aquifer water, or by
collecting rain water in cisterns.
On some of the larger islands of the Lower Keys, small lenses of freshwater to slightly
brackish water float on the top of the Biscayne Aquifer near the ground surface. Chloride
levels in these lenses are generally too high for human consumption, but the lens water is
suitable for some irrigation purposes and provides an important source of freshwater for
wildlife and vegetation.
Natural Groundwater Aquifer Recharge 3 Technical Document: May 2011
Monroe County Comprehensive Plan Update
The amount of water stored in an aquifer is a function, in part, of water inflow, balanced
against the water discharged from an aquifer. This discharge can take the form of either a
naturally occurring flow from springs, lakes or wetlands, or in the form of wells. Should the
water loss exceed the water inflow, water pressures between adjoining aquifers can be
affected, and over drafting, or over mining, can occur, leading to an exchange of water
between the aquifers.
Protection of the functions of natural groundwater aquifer recharge areas and natural
drainage features in the County is a legitimate goal because of the benefits associated with
replenishment of water supplies such as: prevention of lateral movement of salt water from
saline zones (known as saltwater intrusion); dilution of contaminants which could contribute
to the degrading of the ambient water quality; reduction of surface flooding by providing
storage; and prevention of sinkhole formation. The issue of water quality protection must
also be addressed because of the potential for recharge areas to receive contaminants and to
transfer them to underlying aquifers.
12.4 Freshwater Lenses [Rule 9J5. 011 (1)(g), F.A.C.]
On some of the larger keys, a thin lens of freshwater to slightly brackish water floats on top of
the saltier Biscayne Aquifer. The size of the lens is dependent on rainfall, evapotranspiration,
groundwater losses to the marine environment, and pumpage (Hanson, 1980). The large
Upper Keys, Elliott Key for example (Klein, 1970), do not have permanent lenses despite
their large size and the increased rainfall northward. Only the largest of the Lower Keys,
Big Pine and Key West, have permanent freshwater lenses (Parker et al., 1955). The Lower
Keys are more likely to have lenses because of their geometry and geology. These Keys, in
plan view, retain the broad flat of an ooid shoal in contrast to the Upper Keys which are
narrow and elongate parallel to the shelf. In addition, the surficial lithologic unit of the
Lower Keys (oolite) is less transmissive than that of the Upper Keys (reef). Small,
ephemeral lenses occur on other Keys including Sugarloaf Key, Little Torch Key, Cudjoe Key,
No Name Key, Little Pine Key, and Ramrod Key.
The chloride concentrations are usually too high for potable use, but the water is used locally
for irrigation and domestic consumptive uses. Irrigation wells have to be very shallow
because chloride concentrations increase rapidly with depth. On Big Pine Key, only the
upper 15 feet of the aquifer contained water suitable for irrigation (Hanson, 1980). The
freshwater lenses of the Florida Keys are considered to be critical to the support of the
existing wildlife and plant communities in these areas.
Historically, wells were installed in freshwater lenses. Many of these were installed by
private landowners for domestic water supply for the house and/or landscaping, but there
were also some commercial uses such as irrigation for nurseries. The amount of water
withdrawn from wells is unknown, but anecdotal evidence suggests that withdrawals have
declined due to closure of several plant nurseries and due to closure of individual private
domestic wells.
Natural Groundwater Aquifer Recharge 4 Technical Document: May 2011
Monroe County Comprehensive Plan Update
There are many potential sources of contamination to the freshwater lens system because of
its high permeability. The main source of contamination is saltwater intrusion, which can be
caused by over pumping, drought, or sea level rise.
Recharge areas for the lenses are the permeable surface areas above the lenses. There are no
specific maps of recharge areas for the lenses. Big Pine Key has the only permanent
freshwater lens system in unincorporated Monroe County; lenses on other islands are
ephemeral and/or brackish. Figure 12.1 represents the extent of freshwater lenses on Big
Pine Key and is the best approximation of the recharge area for the lenses on that island.
There are no natural drainage features of the freshwater lenses.
12.4.1 Freshwater Lenses on Big Pine Key
There are two distinct freshwater lenses on Big Pine Key. In both lenses, freshwater floats
on the underlying saltwater with changes occurring seasonally due to tidal influences and
rainfall -dependent freshwater recharge (USFWS, 2009). Hanson (1980) mapped the
freshwater lenses in Big Pine Key by monitoring the downhole variation in salinity at
monthly intervals (June 1976 to April 1977) at 22 shallow observation wells. The results
indicated a considerable lateral expansion and contraction of the lens in response to the
seasonal recharge. The maximum thickness of the freshwater column, however, remained
fixed, at approximately 16 feet. A map of the freshwater lens system on Big Pine Key is
presented in Figure 12.1.
Hanson's study (1980) of the fresh water on Big Pine Key found that continued pumping (at
the pumping rate at that time) from shallow wells would probably not damage the system.
However, he projected that future increased withdrawals from new residences and new or
enlarged plant nurseries would "increase the stress on the freshwater lens which can only
supply moderate amounts without detrimental effects during most years." Indeed,
subsequent investigation shows that the effects of urbanization are being exhibited by the
freshwater lens (Stewart et al, 1989). The southeast lens on the Key has decreased in lateral
extent and maximum depth and is clearly affected by saltwater intrusion due to pumping and
canal dredging activities. A modeled simulation of pre -development and current conditions
on Big Pine Key showed that the total volume of the lens has decreased by 20 percent in
response to dredging of canals (Langevin et al., 1998). The maps of freshwater lenses on Big
Pine Key were being updated in 2010 by a consultant to the County but were not vet
available at the time this report was prepared (September 2010).
Natural Groundwater Aquifer Recharge 5 Technical Document: May 2011
Monroe County Comprehensive Plan Update
Ma iA ma mn in WshmLins lenq at IS Pino W (A) tiamndarycOwl.
defink by the cothour of WO nn' L 01 at W-n-] dzpth bei�w i'vawr tahle as mappt:£! n:'
( 198(h Worn I&A Wmanl a- WO Soppod ava hn-."iz of 1
1"w4Ct U"0sS-JwR+i"1 ana obowi hma of Ins a Adamh 1477 tdr; mason),
Adaptcd froin, Vachc.- et all- af`Ler Conirl-11io and Waison, ill) Lc,,canort of
ijllcrfac'.� at sboand dopOis Q 5, and ' in i ,,--%dov,' ',vatcr table: a.,, -)y JcctroT!ia,!nctj:
profiling (Wightnian. 1991A. Dashal I& indicales ninit in ,Maio',! i !9�-7 (dr4, s�.-,isonj, solid iir[�'
indicnew A& in Aiquvt 197 1 arl S"Mcw ; Cims4awhing in 13 hVeme, aran of hngw canak
Ioariy h-nit On; arca. Adapind n"m Vadisr et jai..1991)
Figure 12.1 - Map of Freshwater Lens on Big Pine Key
(excerpted from Halley et al., 1997).
Natural Groundwater Aquifer Recharge 6 Technical Document: May 2011
Monroe County Comprehensive Plan U
12.4.2 Freshwater Lenses on Sugarloaf Key and Little Torch Key
Meadows et al. (2004) studied lenses on Sugarloaf Key and Little Torch Key. The following
is excerpted from their study report. Electromagnetic profiling and groundwater sampling
on Sugarloaf Key and Little Torch Key in the Lower Keys of Florida show that these small,
low-lying islands support only brackish -water lenses. On both islands, the lenses have
central cores with lower salinities surrounded by areas of increasing salinity. The
uppermost few meters of these central zones are uniform and slightly brackish
(approximately 3 parts per thousand) year-round on Sugarloaf Key. On Little Torch Key,
which is smaller, there is a similar central, uniform brackish zone during the wet season,
with salinity slightly higher than on Sugarloaf Key. These lenses are similar in form to
many freshwater lenses, except that the central zone is slightly brackish rather than fresh.
During the dry season, Little Torch Key loses the central brackish zone, and salinities
increase approximately linearly with depth. In the dry -season, the freshwater/saltwater
mixing zone effectively extends throughout the lens. Seasonal variations on Little Torch
Key are less evident outside the central zone. The central lower -salinity core on Sugarloaf
Key coincides with elevations greater than 2.6 feet (0.8 meters). Using vegetation as a
proxy for elevation, the central zone corresponds to the highest elevations on Little Torch
Key as well. Tidal efficiencies on Sugarloaf Key indicate the tidal signal propagates through
the high -permeability, buried Key Largo Limestone, and then upward through the
overlying lower permeability Miami Limestone that contain the lenses. Mixing driven by
tidal pumping is likely responsible for the absence of true freshwater lenses on these
islands (Meadows et al., 2004).
Ross et al. (1994) concluded that sea level rise and associated salinization of groundwater
and soil water is a major factor in the reduction of pine forests of Sugarloaf Key. They also
concluded that if sea level continues to rise, the Florida Keys will experience a decline in both
landscape and species diversity, as species -rich upland communities are replaced by simpler
mangrove communities.
12.5 Biscayne Aquifer [Rule 9J5. 011 (1)(g), F.A.C.]
The Biscayne Aquifer, located throughout southeastern Florida (Figure 12.2), is the largest
supplier of freshwater in southeast Florida. It is the most productive of the shallow
unconfined aquifers in the area and is one of the most permeable in the world (Parker et al.,
1955). The Biscayne Aquifer is considered an unconfined aquifer. In an unconfined aquifer,
water levels are in equilibrium with atmospheric pressure. The upper boundary is termed
the water table. The lower boundary is formed by a relatively impermeable bed.
Natural Groundwater Aquifer Recharge 7 Technical Document: May 2011
Monroe County Comprehensive Plan Update
The rock-v
rhat. cnalpr&ef fhe top of the
[Jesc,azine aquifer vaxy ir
ch.anactcr, Thcy am mostty
tenestone, bw sand marks Oic
top 0; the dauffic), to file
EXPLANATION
RX4, typc* o0roprLsina top of
slscayrw aq[Afer
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Figure 12.2 - Map of the Biscayne Aquifer
(excerpted from Miller, 1990).
M&Owl
197�-
Natural Groundwater Aquifer Recharge 8 Technical Document: -May2011
Monroe County Comprehensive Plan Update
In the Florida Keys, the Biscayne aquifer is approximately 100 feet thick and includes the
Miami Oolite, Key Largo Limestone, and the upper permeable portions of the Tamiami
Formation.
In the Keys, water from the Biscayne Aquifer ranges from brackish to chloride levels
associated with seawater, and requires desalinization for potable use. As a result, the
Biscayne Aquifer in the Keys is not used as a drinking water source and potable water is
piped via aqueduct to the Florida Keys from a wellfield (the Florida City Wellfield) in the
Biscayne Aquifer in southeastern Miami -Dade County. The FKAA is the agency responsible
for obtaining and delivering freshwater to the Keys. They treat the water in Florida City, then
pipe it via aqueduct to Florida Keys residents. Because water from the Florida City Wellfield
is the primary source of potable water to the Keys, contamination by saltwater intrusion or
other contaminants in the Florida City Wellfield would be a disaster for the Keys. Continued
water quality monitoring, and appropriate management to control saltwater intrusion, are
crucial to the protection of the County's water supply and are requirements of the FKAA
Water Use Permit.
As noted earlier, some County residents provide their own water supply using home reverse
osmosis plants to desalinate Biscayne Aquifer water, or collecting rain water in cisterns.
However, due to the limited availability of fresh groundwater and its vulnerability to
saltwater intrusion, and importance to wildlife and native vegetation, very few wells have
been permitted in the shallow aquifer since the 1980s. Review of the South Florida Water
Management District (SFWMD) ePermitting database (accessed June 4, 2010) (Table 12.2)
indicates the SFWMD has issued five current water use permits for facilities drawing water
from the Biscayne Aquifer in the Keys. These include industrial water uses such as
aquaculture/fish tanks and air conditioner heat exchangers. In addition, SFWMD has issued
12 current permits for construction zone dewatering. On the mainland, Everglades National
Park has public water supply permits to draw water from the Biscayne Aquifer for use in the
park office and restroom facilities.
In addition to water use wells, there are injection wells known as Class V wells that are used
to dispose of treated sewage. These Class V wells are permitted by the Florida Department
of Environmental Protection (FDEP). In 2000, there were roughly 750 sewage disposal
wells, ranging in depth from 30 to 90 feet, operating in the Florida Keys. FDEP regulates
underground injection wells according to the federal Safe Drinking Water Act.
Natural Groundwater Aquifer Recharge 9 Technical Document: May 2011
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Monroe County Comprehensive Plan Update
Recharge of the Biscayne Aquifer occurs primarily to the north of Monroe County and
includes (1) infiltration of rainfall or irrigation water through surface materials to the
water table; (2) infiltration of surface water imported by overland flow in the Water
Conservation Areas or by canals; and (3) infiltration of urban runoff by way of drains, wells,
or ponds (Fish and Stewart, 1991). Recharge by rainfall is greatest during the wet season,
from June to November, and recharge by canal seepage is greatest during the dry season,
from December to May (Fish and Stewart, 1991). Recharge occurs throughout most of
Miami -Dade County and the Water Conservation Areas of Miami -Dade, Broward, and Palm
Beach Counties. In the southern part of Miami -Dade County, groundwater flows southward
into Monroe County (Fish and Stewart, 1991).
other water management structures, the effects of pumping, and sea'
Due to several factors (including the low and gentle topography, the effects of canals and
sonal variations in
rainfall), there is not a distinct line that separates aquifer recharge areas from discharge
areas. Areas and canals that are recharge areas at one time (during summer rainstorms or
during the winter rainy season) may be discharge areas during other times. Portions of the
Everglades in mainland Monroe County, for example, alternate between recharge areas and
discharge areas. However, discharge tends to dominate with increasing proximity to
Florida Bay, which is a major regional discharge area in Monroe County. At a regional scale,
the Keys are within the discharge area, but rainfall on the islands provides some localized
and episodic recharge.
Discharge in Monroe County is by: (1) groundwater flow to canals, to seepage areas near
the coast, and widespread and direct seepage into marine waters; (2) evapotranspiration; and
(3) wells pumped for municipal, domestic, or other supplies (Fish and Stewart, 1991).
Groundwater discharge and evapotranspiration are greatest during the wet season when
water levels, temperature, and plant growth rates are high (Fish and Stewart, 1991). In the
Keys where there are no natural rivers, there is no natural drainage of the Biscayne Aquifer
into discernible drainage features such as rivers.
Perennial aquifer recharge areas include the Water Conservation Areas. (Figure 12.3). In
addition, the non -coastal (northern) parts of Everglades National Park and the non -coastal
parts of Miami -Dade County contribute recharge to both the Florida City Wellfield and the
Surficial Aquifer System under Monroe County.
The quality and quantity of raw water in the Biscayne Aquifer is of paramount importance to
regional supply. Aquifer recharge and water storage are the key components of maintaining
an abundant water supply. A major difficulty with the raw water supply is not the average
annual quantity of available water, but the seasonal variability in available quantity.
Approximately 80 percent of South Florida's average annual rainfall occurs during the wet
season from May to September. Water supply issues are addressed in Chapter 8.0, Potable
Water Element.
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Monroe County Comprehensive Plan Update
w8fl1�
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35
Figure 12.3 - Map of Aquifer Recharge Areas for the Biscayne Aquifer
(excerpted from Lower East Coast Regional Water Supply Plan, Planning Document,
prepared by the South Florida Water Management District, May 2000).
Technical Document: may �ui1
Natural Groundwater Aquifer Recharge Element 14
Monroe County Comprehensive Plan Update
Recharge and storage of South Florida's water resources are managed by the SFWMD, an arm
of State government, in coordination with the U.S. Army Corps of Engineers. The regional
water conveyance canals and water storage system, or Water Conservation Areas, were
constructed by the U.S. Army Corps of Engineers with federal funds and are operated and
maintained by SFWMD. SFWMD also determines additional management and construction
needs for the canal or groundwater system and regulates major water inputs and
withdrawals which impact these systems. SFWMD manages and operates its sophisticated
network of floodgates, pumping stations, canals, levees, and Water Conservation Areas to
maintain the delicate balance between flood and drought throughout the year. Groundwater
resources are also proximal to natural areas subject to heightened regulatory protection such
as Everglades National Park. Wet seasonal rainfall is captured and stored in Lake
Okeechobee and the Water Conservation Areas. Water releases from these sources can be
made so that water flows south to Miami -Dade County to aid in maintaining an adequate
water supply throughout the year.
The fresh and salt waters of the region come into contact along the coast. When stream flow
and water tables are high, sea water is prevented from moving inland; when stream flow and
water levels are low, sea water moves up tidal streams and into the aquifer, rendering the
groundwater unpotable in coastal areas. The progressive movement of the saltwater
interface inland has been halted by the SFWMD but the saltwater intrusion problem is a
constant threat in South Florida, especially in times of drought. It is projected that the
region's saltwater intrusion issues will become susceptible to increased risk as South Florida
experiences additional sea level rise. For the Biscayne Aquifer, this may result in reduced
availability of freshwater for potable use which will be even more exacerbated during
periods of drought (Heimlich et al., 2009).
The direct connection between the ground and surface water systems makes the Biscayne
Aquifer susceptible to pollution and disruption from urban activities at the land surface.
Many contaminants are rapidly diluted in the large volumes of water contained in the
aquifer, and the porous limestone acts as a filter. However, high concentration of pollutants
can overload and incapacitate the aquifer's natural cleansing action.
Sources of contamination can be divided between point sources and nonpoint sources. A
"point source" is defined as any discernible, confined and discrete facility that discharges
Pollution. Landfills, impoundments, gasoline stations, septic tanks, and cesspits are examples
of point sources which can contaminate the groundwater aquifers. Because the aquifer is
very permeable, effluent from septic tanks and cesspits moves easily through the drainfield
and can migrate off site. Septic tank effluent characteristically contains bacteria including
fecal coliform and fecal streptococcus as well as other various virus and chemical pollutants.
This could pose public health concerns for those households using well water for
consumptive uses such as bathing.
Nonpoint sources are any discernible sources of pollution not associated with point sources.
They are more pervasive and less controllable sources of pollution. Stormwater runoff from
urban areas is an example of nonpoint pollution which affects both ground and surface
water. Typical components of nonpoint source pollution are those contaminants resulting
Natural Groundwater Aquifer Recharge Element 15
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from the application of substances or the weathering of substances associated with urban
development. Oils and greases, trace metals, pesticides, herbicides and nutrients can be
expected to emanate from urbanized areas. Treatment systems for these pollutants typically
consist of holding areas to attenuate runoff. As such, these areas may contribute pollutant
loads to the surficial aquifer. It is, nevertheless, believed that the risk to the surficial aquifer
is less than the risk to surface waters from direct discharge of runoff.
Several studies have been performed that demonstrate the transmissivity of the substrates
of the Florida Keys and the rapid exchange of wastewater from onsite systems or injection
wells to surface waters. Kruczynski (1999) summarized this information on water quality
of groundwater in the Florida Keys and the following was excerpted from that report.
Lapointe et al. (1990) measured significant nutrient enrichment of groundwater
contiguous to onsite disposal systems at several sites. Mean dissolved inorganic nitrogen
[987 micromolar (uM)] was 400 times higher and mean soluble reactive phosphorus (9.77
uM) was 70 times higher in groundwater adjacent to a septic tank seepage field compared
to a reference site. Concentrations of nitrogen and phosphorus decreased in the
groundwater away from the septic tank toward the adjacent canal, presumably due to
dilution by groundwater. They also theorized that some of the soluble reactive phosphorus
was absorbed by the substrate. Concentrations of nutrients in the canals (dissolved
inorganic nitrogen 4.91 uM; soluble reactive phosphate 0.43 uM) were elevated compared
to control sites: Concentrations of nutrients in the canals were highest in the summer
because of seasonally maximum tidal ranges and increased flushing during the summer
wet season (Kruczynski, 1999).
Shinn et al. (1994) placed and sampled 24 wells beneath the Keys, nearshore areas, and
outer reefs to determine if sewage effluent from Class V wells is reaching offshore reef
areas via underground flow. Class V wells (drilled 90 feet and cased to 60 feet) were
permitted by FDEP for disposal of wastewater. Sample wells were located in transects off
Ocean Reef Club, Key Largo, and Saddlebunch Keys and were sampled quarterly for one
year. Investigators found well water to be consistently hypersaline with a marked increase
in ammonia in offshore groundwater. Other forms of nitrogen and phosphorus present in
offshore groundwater were only slightly elevated above levels found in surface marine
waters. Highest levels of nitrate, nitrite, and phosphorus were found in shallow onshore
groundwaters (Kruczynski, 1999).
Nearshore wells were observed to discharge water during falling tides and draw water into
the wells during rising tides. This "tidal pumping" results in considerable water movement
in and out of the upper few meters of limestone and is a likely mechanism for mixing and
transferring nutrient -rich groundwater into overlying surface waters (Kruczynski, 1999).
Paul et al. (1995) placed a man-made tracer virus in a septic tank and into a 45 foot deep
injection well in Key Largo and found the virus in the surface waters of an adjacent canal
and the Atlantic Ocean in 11 and 23 hours, respectively. Rates of migration ranged from
1.87 to 79.3 feet/hour (0.57 to 24.2 meters/hour). They concluded that current onsite
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disposal practices in the Florida Keys can lead to rapid nutrient enrichment and fecal
contamination of subsurface and surface marine water in the Keys (Kruczynski, 1999).
Paul et al. (1997) repeated the viral tracer experiment with 40 foot deep injection wells on
Key Largo and a permitted 90 foot deep Class V injection well on Long Key. At both sites,
viral tracers appeared in the groundwater within 8 hours after injection, and in marine
surface waters 10 hours in Key Largo and 53 hours in Long Key (Kruczynski, 1999).
Chanton (1998) completed two extensive surveys and mapped areas of concentrations of
natural tracers near the Keys. Groundwater seepage areas were found on both the Florida
Bay and Atlantic Ocean sides of the Keys. Two injection studies were completed: one on
Key Largo and one on Long Key. In both tests, the tracer was injected into groundwaters
and was observed, greatly diluted (approximately one million times) within hours to days
in nearby surface waters. At the Long Key site, it was found in a canal located across U.S. 1
from the injection site. Wastewater injected into the groundwater at Long Key rapidly
migrated toward the surface due to the fact that freshwater "floats" on the highly saline groundwater (Kruczynski, 1999).
Kump (1998) sampled groundwater in wells drilled to various depths surrounding a
wastewater injection. well on Long Key. He confirmed the presence of a shallow, low -
salinity lens floating on top of the groundwater. Distribution of nutrients away from the
site of injection was variable, but phosphate, nitrate, and ammonia concentration appeared
to be highest nearest the injection well at a depth of 16 feet. However, the elevated
concentrations of these nutrients were observed in sampling wells located in different
directions from the point of injection. The absence of phosphate in high pH waters in
shallow wells leads to the postulation that phosphate may be removed by adsorption onto
the limestone substrate (Kruczynski, 1999).
In. October 1996, Kump injected phosphate at the same time that Chanton injected a non -
reactive tracer (sulfur hexafloride- SF6) into a Class V injection well (60/90 feet) at Long
Key. Within 4 hours there were elevated tracers at the sampling well located between the
injection well and the Atlantic Ocean. The peak of both tracers occurred after about 3
hours. After the peak, the ratio of the tracers fell because the concentration of phosphate
fell more rapidly than that of SF6. Using data from one of the sampling wells, it was
calculated that the tracer SF6 appeared to be moving vertically at about 23 feet per day.
The pattern of early SF6 peaks in some wells that are associated with phosphate peaks, and
later SF6 increases with no increase in phosphate concentration at other wells, cannot be
ascribed simply to dilution of phosphate by groundwater. The predicted phosphate
concentrations based on the assumption of no preferential uptake and the observed tracer
concentrations would be well above detection at many of the wells. These observations
support the hypothesis that phosphate is being stripped from the groundwater. The rate
and long term capacity of substrates in stripping phosphate was unknown (Kruczynski,
1999).
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12.6 Floridan Aquifer [Rule 9J5. 011 (1)(g), F.A.C.]
In South Florida, the Floridan Aquifer System is a confined or artisan system. An artisan
aquifer is saturated and is bounded at the top and bottom by completely impermeable beds.
The water level rises above the top of the confined aquifer in tightly -cased wells which are
open only to the artisan aquifer. The Floridan Aquifer System underlies all of Florida and
parts of the adjacent states of Georgia and Alabama. In Miami -Dade County it occurs at about
900 feet below sea level (Parker et al., 1955). It consists of a 1,500 foot thick series of artisan
water -bearing zones within the Tampa and Suwannee Limestones. The Floridan Aquifer
System is confined above by the Hawthorne Group and below by less permeable limestone
and dolomite units. In December 1975, the static head in the Floridan aquifer ranged from
38 to 41 feet above mean sea level in Key Largo (Beaven and Meyer, 1978). Wells into the
Floridan Aquifer System in the Keys range from 75 gpm (gallons per minute) to more than
1,000 gpm, with 750 gpm being the average. Flow rates depend upon the amount of
penetration into aquifer and the types of sediments encountered (Parker et al., 1955).
Although available in significant quantities, Floridan water requires desalinization treatment
before it is suitable for either potable or irrigation use. Chloride concentrations in the
Floridan Aquifer System range from 1,600 to 20,000 milligrams per liter, with concentrations
generally increasing to the south. FKAA has recently been required to construct Floridan
Aquifer Production Wells, a Floridan Aquifer Reverse Osmosis Treatment Facility, and a
Demineralized Concentrate Disposal Well pursuant to its Water Use Permit. Based on the
SFWMD ePermitting database (accessed June 4, 2010) (Table 12.2), there are only three
consumers in the County that are using enough Floridan Aquifer water to require an
individual SFWMD permit: Ocean Reef Community (golf course and landscaping), Silver
Shores Mobile Home Park (landscaping), and Card Sound Golf Course (golf course irrigation).
The Floridan Aquifer System is the best source of raw water for large desalinization
operations because it has low chloride levels compared to the Biscayne Aquifer in the Keys or
compared to seawater. The water in the Floridan Aquifer System has potential as a source of
supply for public and industrial purposes after desalinization. Chloride and dissolved solid
concentrations are major considerations when determining the cost effectiveness of a
desalinization process (Lapointe and O'Connell, 1989). Water from the upper portion of the
Floridan Aquifer System (brackish zone) could provide raw water for treatment at
reasonable cost for large-scale municipal and industrial supply. The Floridan Aquifer System
does not outcrop or receive direct recharge anywhere in South Florida. Therefore, there is
no potential for contamination from surface sources. Concern does exist, however, that large
withdrawals from the Floridan Aquifer could cause upwelling or encroachment of saline
water which in turn would increase production costs for current and future reverse
osmosis/desalinization plants.
As a confined aquifer in South Florida, the Floridan Aquifer System has no natural recharge
areas in South Florida. The Floridan Aquifer System is recharged in central and northern
Florida, southern Georgia, and small parts of adjoining Alabama and South Carolina. There
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are no natural recharge areas within the jurisdiction of Monroe County. With no natural
recharge in Monroe County, maps of recharge areas are not applicable.
12.7 Regulatory Framework [Rule 9J5.011(1)(h), F.A.C.]
The overall intent of federal and State regulation of groundwater aquifers is the protection of
public drinking water supplies from contamination. The protection of water table levels and
the regulation of aquifer withdrawals are primarily under the domain of the SFWMD, while
water quality is regulated by FDEP. These agencies may also be involved in the preservation
of freshwater resources in general where they are not used for mass public consumption, but
the effective regulation of these resources are carried out mainly at the local government
level.
In the Florida Keys, lenses are not recognized as a source of potable water supply and,
therefore, are not subject to potable supply regulations.
12.7.1 Federal Regulations
U.S. Public Law 104-182, "Safe Drinking Water Act" was enacted on August 6, 1996, to
reauthorize and amend the prior law to continue implementing a nationwide system of
monitoring and controlling the quality of water supplied by public water systems. The U.S.
Environmental Protection Agency (USEPA) was given authority to administer the Act. In
addition, the Act also required USEPA to develop criteria for selecting critical aquifer
protection areas. The program calls for state and local governments to map those areas and
develop protection plans, subject to USEPA review and approval. Once a plan is approved,
USEPA may enter into an agreement with the local government to implement the plan.
The Safe Drinking Water Act provides for the protection of public water system wellfields
and aquifers used as the sole source of a community drinking water supply. Amendments
provide for wellfield protection which require states to work with local governments
through the planning process to identify and to protect wellhead areas.
USEPA is currently promulgating additional Water Quality Standards for the State of
Florida's Lakes and Flowing Waters, 40 CFR Part 131, which regulate discharges that impact
surface and groundwater resources.
12.7.2 State Regulations
USEPA generally regulates water quality standards, although water quality standards at the
State level are developed by FDEP and adopted by the Environmental Regulatory
Commission. FDEP is charged with enforcing the standards, although it may delegate some
of its authority to the regional water management district or other governmental units.
Other regulatory authority, such as the land use zonin
impact water quality g Powers of local government, directly
and the SFWMD has established a program to address water resource
concerns related to land use and other comprehensive plan issues.
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The permitting programs of SFWMD and FDEP achieve their joint goal through different
mechanisms. FDEP's statutory authority and regulatory program for protection of the State's
water quality addresses discharges into the waters of the State. This program is
distinguished from the SFWMD regulatory water use program which addresses withdrawals
from surface and ground water sources. The SFWMD program protects the quality of the
State's water resources (primarily related to the movement of constituents). Decisions in
this program can cause discharge of pollutants into the water resources through the
transport of pollutants in "used" water.
FDEP Rules within Chapter 403, F.S., "Florida Safe Drinking Water Act," and Chapter 62-528,
Part III, F.A.C., classify and regulate the use of aquifers. The FDEP has also developed
increasingly stringent regulatory requirements for facilities which discharge to groundwater
under Section 62-528, F.A.C., and for those facilities which inject materials underground
through deep well injection. Groundwater quality standards are included in Chapter 62-528,
F.A.C., with Florida Keys groundwater generally falling under Class G-III criteria. These
criteria set standards for protection of public health in general and the protection of natural
systems from toxic substances, but nutrients are not addressed.
The SFWMD consumptive use permitting program regulates quality issues associated with
water withdrawals by evaluating the potential for a withdrawal to cause the following:
• saltwater intrusion;
• harm to offsite land uses;
• harm to wetlands or other surface waters;
• pollution of the water resources;
• is otherwise reasonable -beneficial;
• interfere with presently existing legal uses;
• is in accordance with Section 373.2295, F.S. relative to the interdistrict transfer of
groundwater and Section 373.223(3), F.S. concerning water transport and use of
groundwater or surface water across county boundaries;
• appropriately makes use of reclaimed water;
• is consistent with the public interest;
• is in accordance with established minimum flows and levels; and
• will not withdraw water reserved under Chapter 40E-10, F.A.C.
The SFWMD also requires well plugging pursuant to Chapter 373.207, F.S., to prevent the
movement of saline water into freshwater aquifers.
The SFWMD uses FDEP's water quality standards and water body classifications to
determine the water quality status of aquifer and surface waters. The SFWMD will
recommend to FDEP new standards (including site -specific alternative criteria) or
classifications as necessary to protect the water resources of the state.
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In the development of Surface Water Improvement and Management plans, water supply
plans for specific geographic subregions, and other planning documents, the SFWMD may
identify areas and water bodies for which additional protection is necessary. The
development of such water quality guidelines or caps will be done in coordination with
FDEP. The SFWMD will continue to develop or support initiatives such as the wellfield
protection programs to assist local governments in linking water quality with land use
decisions. The SFWMD Surface Water Improvement and Management process will identify,
recommend and implement solutions for water quality problems within specific priority
water bodies.
The SFWMD may allow movement of lower quality water into a higher quality aquifer to
occur only in limited, defined circumstances when the use is necessary for maximum
reasonable -beneficial use and is consistent with the FDEP ground water classification. To
achieve water quality protection and enhancement in these situations, it is recommended
that the regional water supply plans establish boundaries and recommend water quality -
caps beyond which a use may not degrade an aquifer, as consistent with state water quality
standards.
As a corollary, the SFWMD regional water supply plans may establish areas of water quality
which, on a local or regional level, may have already exceeded the recommended limits. In
these instances, the SFWMD may apply regulatory means of enhancing water quality, to the
extent possible, to meet the specified water quality requirements of the defined area.
However, SFWMD caps will not allow degradation of a source to a point which exceeds the
FDEP classification for the water body. The SFWMD will encourage linkage of the proposed
groundwater boundaries and caps with local government land use decisions similar to
wellfield protection ordinances with the intent that local governments make land use
decisions based on potential aquifer development as consistent with the water quality
protection and enhancement goal.
12.7.3 Local Regulations
At the present time, the County has no special regulatory programs related to protection of
natural groundwater aquifer recharge areas, nor has there been any comprehensive
identification of these areas. While Chapter 380, F.S., does express concern for preservation
of freshwater wetlands for wildlife, the only specific regulation directly affecting
groundwater is the prohibition of well excavation in "high quality pineland" areas. Existing
local regulations presently affecting ground water pollution sources are mainly limited to
those addressing stormwater runoff.
12.7.4 Wellfield Protection
In 1983, FDEP began developing a wellhead protection program to prevent contamination of
public water supplies. The program, known as the GI -Rule, is based on groundwater quality,
a five-year travel time contour, and a calculated radius of protection. Since its adoption, the
GI -Rule has been challenged in court and as a consequence has not been successfully
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implemented. However, FDEP encourages and supports local governments to take the lead
in protecting their drinking water supplies and is assisting the Florida Department of
Community Affairs with related comprehensive planning.
For Miami -Dade County, wellfield protection planning began in the late 1970s. The Wellfield
Protection Program is based on the need to protect the drinking water resources from
potential contamination and the delineation of prohibitive or protection zones. Various
wellfield protection zones are identified based on modeled contaminant travel time and
drawdown. Specific wellfield protection rules are located in Chapter 24-12.1 of the Code of
Miami -Dade County.
The FKAA wellfield is located just west of Florida City and consists of 10 operational wells.
Each well extends into the Biscayne Aquifer, which serves as the primary raw water source.
Raw water quality at the FKAA wellfield has historically been acceptable for potable water
supply. Water quality data included in the permit modification application indicated that the
water is hard and low in turbidity, color and iron. Review of the data for the 2008
application (SFWMD Water Use Permit No. Re -issue 13-00005-W, March 2008) indicated
that water quality had changed little if any as a result of current withdrawals. No percolation
ponds, hazardous or toxic waste disposal sites, sewer mains, saline water bodies or
wastewater treatment facilities are located within a 1 mile radius of the wellfield. The
Wellfield Protection Program (CH2MHill, 2010) identifies potential contamination sources.
The FKAA wellfield is currently protected by the Miami -Dade County Wellfield Protection
Ordinance which is administered by the Department of Environmental and Resource
Management.
A condition of the permit requires FKAA to monitor and submit data from the Salt Water
Intrusion Monitoring program to the SFWMD on a monthly basis. In accordance with an
additional condition of the permit FKAA is implementing a Saline Water Intrusion Monitoring
program which utilizes monitoring wells to measure any movement of the saline water
interface. An example of the SFWMD criteria to prevent saltwater intrusion is that 1 foot
head of fresh water be maintained between the wellfield and the saline water source.
Saltwater intrusion usually results from a sustained decrease in fresh water head, allowing
saltwater to migrate inland. Results of groundwater modeling indicate that drawdowns
associated with increased withdrawals are minimal. The FKAA in cooperation with the
United States Geologic Survey (USGS) maintains a water quality monitoring network around
the wellfield that is sampled monthly. The network includes 15 monitoring wells, 2 of which
have continuous water level recorders. The Wellfield Protection Program (CH2MHill, 2010)
identifies the well locations and provides analytical data. From the data included in the 2008
Application for Water Use Permit Modification Renewal, it was concluded that in 2008 the
1,000 milligrams per liter isochlor is estimated to be six miles southeast of the well field in
approximately the same location reported in 1974.
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12.7.5 Freshwater Lens Resources
The freshwater lens systems of the Florida Keys are considered to be critical to the support
of the existing wildlife and plant communities in these areas. There is a need for continued
efforts towards monitoring their condition, including size and water quality. Protection of
the lens systems should be accomplished through regulation of withdrawals and of land use
in recharge and wetland areas. Of particular concern are: freshwater withdrawals for private
consumptive uses, loss of recharge areas to impervious surface coverage, contamination of
groundwater from surface sources, and salt water intrusion due to sea level rise.
It has been demonstrated that the freshwater lens on Big Pine Key has suffered some
reduction from its former size. While droughts and sea level rise may be contributors to this
phenomenon, it cannot be disputed that freshwater withdrawals have their effect on the lens.
New dredge and fill projects are largely prohibited in the Keys both by State and local
governments. Further increases in private consumptive withdrawals should not be
permitted and alternative water sources are needed.
The current Stormwater Management Ordinance does address the need to handle
stormwater on site, but it does not stress the need to retain natural drainage features and
reduce impervious surfaces. Standards are needed to ensure impervious surfaces do not
reduce the quantity or quality of aquifer recharge to the point where the natural resources
are significantly degraded. Incentives could be provided to reduce existing impervious areas.
Specialized requirements or incentives may be appropriate in areas that serve as aquifer
recharge areas for freshwater lenses. Acquisition of important recharge areas may also be an
option for preservation.
The County already implements some regulations that serve the purpose of protecting the
freshwater lens recharge areas. Mining can pose a threat to recharge areas. Therefore, the
County prohibits any resource extraction activity that would cause the introduction of
saline aquifer waters into fresh water aquifers.
In addition, a habitat analysis is required for any proposed development in slash pinelands
or tropical hardwood hammock. Since pineland habitat is an indicator of freshwater lens
recharge areas, the County now requires a relatively high open space ratio in these areas.
The County also requires on -site retention of stormwater, which helps the fresh water filter
into the ground and eventually into the freshwater lenses, instead of draining to lower
ground where it would more likely evaporate or drain into the ocean.
12.7.E Water Conservation
The Water Resources Act of 1972 formally designated the conservation of water as a key
Policy of the state and mandated that state and regional water resource agencies take steps
to prohibit wasteful and unreasonable uses of the states water supply. For South Florida, the
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Monroe County Comprehensive Plan Update
adoption of the act also thrust the SFWMD into a lead role in water supply planning and
regulation.
Water conservation is a high priority in SFWMD policy and rules as well as FDEP rules, in
keeping with the statutory mandate. Implementation of demand management programs will
be both passive (public information) and active (irrigation using micro -irrigation systems,
use of reclaimed water, leak detection, water conservation rate structures, model landscape
codes, use of rain sensors, ultra low flow plumbing structures in new construction, etc).
As part of its efforts to conserve freshwater resources in areas of high demand, the SFWMD
will continue to analyze and support the development of alternative water sources such as
use of Floridan Aquifer withdrawals, reverse osmosis, and use of reclaimed water. Also, as
noted below, the SFWMD will continue to investigate and support other supply
augmentation alternatives. The development of other supply sources, however, does not
lessen the requirements for conservation and efficient water uses. As discussed below,
inefficient or wasteful uses of water are not considered reasonable or beneficial under
Florida law.
A related concept found in Florida's water use policy is the use of the lowest quality water
available and appropriate for a specific use. This policy, for example, encourages the
replacement of high quality ground water with treated wastewater for irrigation purposes if
a feasible source is available. The effect of this policy is to optimize the utilization of
available resources by requiring diversification of sources. The SFWMD identifies areas that
have or will experience water supply problems in the next 20 years. During the past decade,
the use of potable water for lawn and landscape irrigation has drawn extensive attention,
culminating in new year-round water conservation rules, and has been the focus of
numerous conservation campaigns. These efforts have included water shortage awareness
campaigns and Florida -Friendly (low -irrigation landscaping) programs.
Some water conservation measures are identified in the County Code of Ordinances.
Examples include restrictions on landscape irrigation during certain times of the day when
evaporative losses are high, unnecessary watering of impervious areas, and rain sensors on
irrigation systems - new installations of automatic irrigation systems must be equipped
with a water sensing device that will automatically discontinue irrigation during periods of
rainfall (Code of Ordinances, Chapter 12, Article IV, Section 12-82). There are also potable
water conservation standards, including the requirement for installation of toilets with a
maximum flush of 3.S gallons, showerheads and faucets with a maximum flow rate as
specified in the Florida Building Code; and independent water systems are encouraged
whenever permitted (Code of Ordinances, Chapter 12, Article III, Section 114-46).
Additional water conservation measures may be applicable, including incentives for water
conservation features installed on remodeling work that does not otherwise require
upgrades to meet current codes.
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Bibliography
Beaven, T. R. and F.W. Meyer, 1978. Record of Wells in the Floridan Aquifer in Dade and
Monroe Counties. U.S. Geological Survey.
CH2MHill, 2010. Wellfield Protection Program. Prepared by CH2MHi11 for the Florida
Keys Aqueduct Authority, February 2010.
Chanton, J., 1998. Use of natural and artificial tracers to detect subsurface flow of
contaminated groundwater in the Florida Keys National Marine Sanctuary. Final Report
submitted to the Water Quality Protection Program, 52 pp.
Fish, J.E. and M. Stewart, 1991. Hydrogeology of the Surficial Aquifer System Dade
County, Florida. U.S. Geological Survey, Water -Resources Investigations Report 90-4108.
Halley, R.B., H.L. Vacher, and E.A. Shinn, 1997. Geology and Hydrogeology of the Florida
Keys. Geology and Hydrology of Carbonate Islands - Developments in Sedimentology, V. 54,
edited by H. L. Vacher and T. Quinn. http://sofia.usgs.gov/ publications/papers
/keys_geohydro/index.html.
Hanson, C.E., 1980. Water Resources of Big Pine Key, Florida. U.S. Geological Survey Open -
file Report 80-447, 36 pp.
Heimlich, B.N., F. Bloetscher, D.E. Meeroff and J. Murley, 2009, Southeast Florida's Resilient
Water Resources: Adaptation to Sea Level Rise and Other Climate Change Impacts, Florida
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