Lake Regions of Florida
Florida's lakes provide important habitats for plants, birds, fish, and other animals, and
comprise a valuable resource for human activities and enjoyment. More than 7,700 lakes are
found in Florida, and they occur in a variety of ecological settings. The physical, chemical,
and biological diversity of these lakes complicates lake assessment and management. In many
states, it has been shown that water resources can be managed more effectively if they are
viewed within a regional framework that reflects differences in their quality, quantity,
hydrology, and their sensitivity or resilience to ecological disturbances. To develop cost-
effective lake management strategies that protect or restore water quality in Florida lakes,
regional differences in the capabilities and potentials of lakes must be considered. Hydrologic
unit or basin frameworks are often used for water quality assessments and ecosystem
management activities, but these units or basins do not correspond to the spatial patterns of
characteristics that influence the physical, chemical, or biological nature of Florida lakes.
General patterns of geology and physiography have been used previously to explain regional
differences in Florida lake water chemistry (Canfield and Hoyer 1988; Pollman and Canfield
1991), and ecosystem characteristics of Florida lakes have been summarized (Brenner et al.
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1990). Building on this work, as well as on a Florida ecoregion framework (Griffith et al.
1994), we have defined these forty-seven lake regions as part of the Florida Department of
Environmental Protection's (FL DEP) Lake Bioassessment/Regionalization Initiative. The
spatial framework was developed by mapping and analyzing water quality data sets in
conjunction with information on soils, physiography, geology, hydrology, vegetation, climate,
and land use/land cover, as well as relying on the expert judgment of local limnologists and
resource managers. This framework delineates regions within which there is homogeneity in
the types and quality of lakes and their association with landscape characteristics, or where
there is a particular mosaic of lake types and quality. More detailed descriptions of methods,
materials, and lake region characteristics can be found in Griffith et al. (1997). The identifier
for each lake region consists of two numbers: the first number (65, 75, or 76) relates to the
United States Environmental Protection Agency (US EPA) ecoregion number (Omernik 1987;
US EPA 1997), and the second number refers to the Florida lake regions within an ecoregion.
The Florida lake regions and associated maps and graphs of lake chemistry are intended to
provide a framework for assessing lake characteristics, calibrating predictive models, guiding
lake management, and framing expectations by lake users and lakeshore residents.
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Small ponds and reservoirs on red sandy soils are typical in region 65-01
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The rolling hills of the Western Highlands lake region are covered by mixed hardwood and pine forest,
with some cropland and pasture. It is a region of streams, but very few natural lakes. The region contains
some oxbow lakes and other lowland lakes of the river floodplains. A few ponds and small reservoirs for cattle or
recreation have been created by damming up small drainages. Similar to the streams of the region that feed these
small reservoirs, they would generally be acidic, softwater, low to moderate nutrient lakes, if lake management
inputs were low. However, most lakes in this region, including Karick, Hurricane, and Bear lakes, have been
artificially limed and fertilized in an attempt to increase fish production. Phosphorus values have increased for
some of these lakes from the 10-20 pg/1 range in the 1970s to more than 70 pg/1 in the 1990s.
The Dougherty/Marianna Plains lake region is an eroded limestone area that is generally more flat than
the regions to the east and west, with agriculture as a dominant land use. Elevations are generally 100 to
200 feet, but include Florida's high point of 345 feet in northwest Walton County. The Floridan aquifer is at or
near the surface in much of the region. The solution activity on the limestone bedrock has formed numerous
sinks, caverns, springs, and other karst features. Many of the shallow depressions or sinks, often called bays,
dome swamps, or gum ponds, contain ponds or small lakes surrounded by cypress trees and other hydrophytic
vegetation. The limestone is exposed in some areas, but in other areas, sands and clayey sands reach thicknesses
of over 200 feet. The chemical characteristics of lakes in this region can be variable depending upon a lake's
contact with bedrock or its isolation from the bedrock by deposits of clays and sands. Most of the lakes can be
characterized as relatively clear, acidic to slightly acidic, softwater lakes; generally oligo-mesotrophic or
mesotrophic. Merrits Mill Pond is spring-fed and different, with high pH. hard water, and high nitrogen. Lake
DeFuniak is surrounded by urbanization, but remains clear and unproductive with low color and low nutrients.
05_ The New Hope Ridge/Greenhead Slope is an upland sand ridge region, 100-300 feet in elevation, with a
__ relatively high density of solution lakes for the Florida Panhandle. Similar to other well-drained upland
sand ridge areas in Florida, the region is a high recharge area for the Floridan aquifer. It contains clear, acidic,
softwater lakes of extremely low mineral content. The lakes are very low in nitrogen and phosphorus, low in
chlorophyll a, and are among the most oligotrophic lakes in the United States. Along with lakes in the Trail Ridge
region (75-04), these may be some of the most acid-sensitive lakes in Florida. Lakes connected to stream
drainages, such as Black Double Lake and Lighter Log Lake in Washington County are more colored.
The characteristics of the Tifton/Tallahassee Uplands region change distinctly from west to east. The
region contains a heterogeneous mosaic of mixed forest, pasture, and agricultural land. The dissected
Tifton Upland in the western par of the region has few if any natural lakes, but many small ponds and reservoirs
created on stream channels The southwest part of the region consists of thick sand delta deposits and contains
one small lake, Lake Mystic (Liberty County), and a large reservoir. Lake Talquin, impounded in 1929, is the
second-oldest large reservoir in Florida. To the east of the Ochlockonee River, in Leon County. karst features are
more evident with many solution basins, swampy depressions and some large swamp lakes. Some lakes, such as
lamonia and Jackson, drain periodically when their karst drainage system becomes unplugged. Lakes in this
region tend to be slightly acidic to neutral, colored, softwater lakes with moderate nutrient values. Some lakes
have high pH and conductivity values because groundwater is pumped in to counteract draining,
SThe Norfleet/Spring Hill Ridge lake region contains small, upland, clear, low-nutrient, acidic lakes that
differ from the darker, swampy, moderate nutrient lakes of the Tifton/Tallahassee Uplands (65-04) and
Gulf Coast Lowlands (75-01) regions. It is somewhat of an anomalous area of xeric sand hills that extend into
the Gulf Coast Lowlands, with elevations generally 60-120 leet. Acid-tolerant aquatic plants ate found here, as
most of the lakes have pH levels less than 5.5. Some lakes and ponds show some color associated with rain
events, especially Moore Lake and Loften Ponds.
t The Northern Peninsula Karst Plains region is generally a well-drained flat to rolling karst upland
Containing a diverse group of small lakes. The natural vegetation consisted of longleaf pine/turkey oak.
or hardwood forests on the richer soils, but agriculture is now extensive in much of the region. With some areas
underlain by the geologically diverse Miocene Hawthorn Group or by undifferentiated Quaternary sediments,
nutrient levels are variable, but many lakes have high phosphorus. The region's nutrient values are some of the
highest in northern Florida. Many of the lakes are located in an area between Live Oak and Lake City.
Groundwater connections as well as human activities elevate the conductivity and phosphorus in some lakes
around Lake City. The mosaic of lake types in this region has a wide-ranging distribution of chemical and
physical characteristics, but in general the lakes tend to be slightly acidic, with low to moderate alkalinity, high
nutrients, and some color.
Many clearwater lakes are found in region 65-03. and a few
clearwater lakes, such as Lake Cassidy, occur in 65-02.
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PRINCIPAL AUTHORS Glenn Griffith (US EPA), Daniel Canfield, Jr. (University of Florida), Christine"
Horsburgh (University of Florida), James Omernik (US EPA), Sandra Azevcdo (OAO Corp.)
COLLABORATORS AND CONTRIBUTORS Mark Hoyer, Eric Schulz, Roger Bachmann, and Sandy
Fisher (University of Florida): James Hulbert, Michael Scheinkman, Ellen McCarron, and Russ Frydenborg
(FL DEP); Craig Dye (Southwest Florida Water Management Dstrict), Alan Woods (Dnam.ic Corp.);
Curtis Watkins (Florida Lake Management Society); citizen volunteers of Florida LAKEWATCH
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Lake conditions vary in this suburbanized
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LAKE REGION CHARACTERISTICS
The maps below illustrate some of the regional differences in the characteristics of Florida lakes. An understanding of regional differences in the current status of lakes, as well as of
potential or attainable conditions, is important for effective lake management. The maps are derived from mean lake data from 1,133 lakes, sampled between 1979 and 1996. Most of the
data (82%) are from lakes sampled between 1990 and 1996. The data are from the University of Florida (54%), the LAKEWATCH program (34%), the U.S. EPA's Eastern Lake Survey
(8%), and from the U.S. Forest Service (4%). Lake data from the Florida Department of Environmental Protection, the Florida water management districts, and other sources were also
assessed for the delineation of the lake region boundaries, but are not included in these chemistry maps or histograms due to differences in detection limits, sampling methods, duplication
of lakes, or other quality control and comparison efforts. The maps are color-coded by the median value for each lake region. A median, or middle value, is used as a measure of the
87o 86 85 840 83 82 81 80
i1 i~1~Z I ---- ___~-
central tendency of a region's data because it is less skewed by extreme values than is the mean or average value. In regions where there were insufficient data (generally less than three
lakes sampled), the regions were not color-coded unless there was confidence that the one or two lakes represented the region's total population of lakes or ponds. In some regions, the
extrapolation of the median value to the entire region can give a misleading view of the spatial distribution of the actual lake values. However, the maps do help portray some of the
statewide patterns and regional tendencies. The histograms on the phosphorus and alkalinity maps illustrate the frequency distribution, or range of variation, of the lake values in each
Total Phosphorus (lgg/l)
Rc -.., l nic.ian value
fki or no lakes
75-091 j .
-. d,4i~1 .b
65-01 65-02 65-03
1191 00 190
o =4 91 n i7 90 n=28
so 90 80 -
.l L. _
Totaal akalinity (mg)
Totalal kalinlty (mg/l)
0g n = 50
Total alkalinity (mg/.)
Total alkalinity img1)
Total alkalinity (mill
._ 60 0
Total alkanty (mgi)
Total alkalnny (mgll)
Tolal alkalinily (m/l)
Tol a alkalinity 9mg/1)
ol n 5
Tolal alkahnny (mg@
Total alkaliniy (mg/1)
Total alkainity (m1. )
Total alkalhmly (mgl)
Total alkalinty (m. )
Total alkalinity (mg/1)
Total Al kal in i i ie o'
Ill, di r r lue
4 II 'I 0'
tle or ni ti likes
Total alkahnty (mg/1)
Total alkalinity (mg/1)
Total alkalinity (mg/A)
Total alkalinity (mgnl)
Total alkalinity (maSl)
Total alkainty (mlg/1)
Total alkalinity (mg1l)
Total alkalinity (mg/i)
Toaal alkalinty (mgl)
T1a.l alk.lini.y (m7ll)
90 n9 9
Total alkalinity (ng/i)
Total alkalinity (mgl)
Total alkalinity (nal)
nm n= 9
Toial alkalhmly lg/l
Total Jlalkalim (m/1)
Total alkalinity (mg/il
Total alkalinity (mg/1)
00 7 0 -
10 I I
Tolal alkalinity (.g/I)
Total alkalinity (mg/1)
al alalny (1
Tolal alkalnmty 4011
I S i;L
Total alkalinity mg/l)
Total alkhlnaty (mgl)
Tot al lallla y (mg/ll
Js (. I
Toal alalli9nit (mg/l)
Total phosphorus is a measure of one of the primary nutrients that regulates algal and macrophyte growth in lakes. Phosphates can enter the aquatic system primarily through terrestrial runoff as well as through groundwater percolation, with minor or negligible amounts from
atmospheric deposition. Phosphate loadings can be increased above background levels with inputs from sewage treatment plants, industrial sources, agricultural and residential runoff, or from phosphate mining and fertilizer processing activities. High phosphorus
concentrations can accelerate the process of eutrophication. The highest regional phosphorus values are found in southwest Florida (e.g., regions 75-30, 75-36) where phosphates are often naturally high, and the lowest regional values are found in some of the upland sandy
ridges (e.g., regions 65-03, 65-05, 75-04, and 75-33).
Total alkalinity measures the components in water, such as carbonates, bicarbonates, and hydroxyl bases that tend to elevate pH and buffer against increases in acidity. Although much of Florida is underlain by limestone, many lakes in the state are isolated from the limestone
layers by overlying sands and are softwater, acidic lakes with low alkalinity. Low alkalinity is found in many clear lakes of some of the sandy upland ridge regions (e.g., regions 65-03, 65-05, 75-04, and 75-09), as well as in some darkwater lakes in lowland regions (e.g.,
regions 75-01, 75-02, 75-10). Higher alkalinity is generally found in central and southern Florida or in lakes with groundwater influences. High alkalinity occurs in lake regions where limestone is near the surface (e.g., regions 75-06, 75-12), where lakes are limed for fish
production (e.g., region 65-01), or in urbanized regions with a combination of groundwater influence and human disturbance (e.g., regions 75-21, 75-28).
n 1 -
., ,,-. = ." .
Total Nitrogen Iqg/l~ I
I ,: -111
I III Irt
I" r ii, Idj e-
Total nitrogen is the combined measure of nitrate, nitrite, ammonia, and organic nitrogen found in a lake. Nitrogen is
an important nutrient to many aquatic organisms, serving with phosphorus as the nutrient base for primary productivity.
Nitrogen can enter the aquatic system through atmospheric deposition, groundwater, terrestrial runoff, and atmospheric
nitrogen fixation by cyanobacteria (blue-green algae). Nitrogen levels of lakes can be increased above background
levels by inputs from sewage treatment plants, citrus and agricultural runoff, or other urban and residential sources.
Chlorophyll a (gg/1)
Regional median value
few or no lakes
Chlorophyll a is the predominant form of photosynthetic green pigment found in plants and algae. As an indicator of
phytoplankton biomass, it is used to approximate algal levels in a lake. It is correlated with total phosphorus and Secchi
depth, and helps indicate the trophic condition of lakes. While many of Florida's shallow lakes have low chlorophyll a
levels, a large part of the nutrient pool may be used by the aquatic plants called macropyhytes. In some nutrient-
enriched lakes, blooms of blue-green algae or cyanobacteria can kill fish and create other problems for lake users.
Color (Pt-Co units)
Regional median value
I 100 200
few or no lakes
Color or true color of a lake is a measure of th: dissolved and colloidal substances in water that reduce light
transmission. It is measured in comparison to a seal d series of platinum-cobalt unit (Pt-Co units) color standards. The
decreased light penetration in high color or humic-stained darkwater lakes can reduce some macrophyte productivity
and the extent of the littoral zone. The sandy uplai d ridges generally contain the lakes of lowest color, while most of
the darkwater lakes are found in lowland flatwoods regions or swampy areas that have peat and organic soils.
1 **?.' 1 .30 n llu.
I I I.I
I l 1-''1
]few or no lakes
Secchi depth is a simple measure of water clarity or transparency. Water clarity is determined by measuring the depth
at which a black and white disk disappears from view. The Secchi depth is dependent upon the algal levels, color, and
total suspended solids in the water, among other factors. The low-color lakes of the upland ridges (e.g., regions 65-03,
75-04. 75-09, 75-15, 75-20, and 75-33) generally have the greatest Secchi depths.
The pH of a lake is a measure of its hydrogen ion concentration and tells whether it is acidic or basic (alkaline). Many
of Florida's lakes are acidic and have been acidic throughout their history, with the biological communities adapting to
these conditions. Regions of high pH (alkaline) are mostly found in central and southern Florida, or in the north where
limestone is near the surface (e.g.. region 75-06) or the lakes are artificially limed (e.g., region 65-01).
' I -
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