Lake Eola and its famous fountain, downtown Orlando

Jewels in the landscape, Florida's lakes and ponds are among our most valued natural resources. Each lake in Florida is a unique combination of ecologic, morphologic, hydrologic, and geologic qualities. From the clear sandhill lakes of the "high" Florida ridge, to the green life-filled lakes of the "valleys", each plays crucial roles in irrigation, flood control, drinking water supply, recreation, navigation, and as habitats for plants and wildlife.

Several thousand of our lakes and ponds were naturally formed eons ago through geologic processes; thousands more are artificial, constructed in housing developments, shopping centers and golf courses. They vary widely in shape, depth, and size, as well as in water chemistry and quality.

Florida's lakes reign as some of the most "biologically productive" systems in the world. The state's climate and topography provide year round growing seasons for large aquatic plants (macrophytes), as well as for microscopic plants (algae, phytoplankton). Besides supporting the growth of native plants and animals, Florida's lakes also are susceptible to invasive plant species, algae blooms and nuisance native plant overgrowth.

Among other things, proper plant management in Florida's lakes is key to maintaining healthy lake ecosystems and ensuring their intended functions.

Almost 8,000 lakes in Florida offer unlimited recreation.

LAKE FORMATION and TYPES
Lake type is determined by the manner in which lake formation took place, and by the surrounding environment. Natural lakes in Florida were formed in a variety of ways by the forces of nature; artificial lakes were formed by the forces of man.

Natural lakes
Florida has more natural lakes than any other state in the southeast. Unlike the large, deep lakes of the northern U.S. which were generally formed by glacial processes, most of Florida's shallow and sloping lakes were primarily formed by erosion and/or collapse of the karst limestone bedrock.

Lake Yale

Solution (sinkhole) lakes. The most common origin of lake formation in Florida is by karst erosion, a chemical process that takes place when underground limestone is dissolved by carbon dioxide enriched water. Most solution lakes are a result of sinkhole activity and thus are circular, steeply sided and deeper than other Florida lakes. Shape irregularities develop due to adjacent sinkholes or additional subsidence. Solution lakes primarily occur in clusters. Examples are the many connected lakes in the Tsala Apopka marsh of Citrus county and Lakes Harris, Griffin, Eustis, and Yale of Lake County.

Lake Okeechobee

Depressions in ancient seabed. Some lakes are natural depressions in the ancient limestone bedrock that were formed by wave action or water currents as sea levels rose and fell over millions of years. Generally, these lakes are shallow bowl-shaped waterbodies that are only a few meters deep. Except for a notable exception or two, depression lakes are generally elongated, or appear threaded together, along the coast or near rivers. Examples include Lake Okeechobee, Long Pond and Lakes Washington, Winder, and Helen Blazes at the headwaters of the St. Johns river.

Lake Monroe

Fluvial development. The least common origin of Florida lakes is through fluvial (river) processes as the river carries and deposits sediments along the river bank. River processes can enlarge existing water bodies, create natural levies that separate and form a new waterbody, or leave a remnant oxbow waterbody as a river changes its course. Like depression lakes, fluvial lakes appear elongated and occur in linear chains or as U-shaped oxbow lakes. Examples include Lake Harney, Lake Hernando, and Lake Monroe.

Dune Lake

Coastal dune lakes. Coastal dune lakes are the result of long shore currents that deposit sediments along a coastal inlet or bay. Eventually, water in the inlet or bay is cut off from the sea and a saltwater waterbody is created. As the lake becomes increasingly landlocked and saltwater intrusion ceases, a freshwater lake is formed. However, hurricane activity can create intermittent periods of salinity. Examples of coastal dune lakes primarily occur in the Panhandle and include Camp Creek, Draper Lake, and Big Red Fish Lake.

Ocean Pond

Extraterrestrial influences. And some of our lakes may have been formed by meteorites slamming into Earth, which is suggested for the formation of Ocean Pond in Baker County.

Artificial lakes
Although most natural lakes in Florida have been physically altered in order to accommodate water management objectives, many lakes throughout the state are completely artificial. These lake waterbodies are created for aesthetic pleasure, drainage, flood control, irrigation, navigation, fishing, recreation, stormwater treatment, water for livestock, to provide fill material, and/or to increase property values.

Lake Seminole

Reservior lakes. These "lakes" are created by building a dam or weir across a river and flooding low areas behind. People have been building reservoir structures for more than 3,000 years in order to facilitate navigation, fishing, and access to drinking water. Modern examples include the Rodman Reservoir, Manatee Lake, Lake Seminole, Lake Talquin, Lakes Karick and Hurricane, and Lake Rousseau.

Retention Pond

Retention ponds. Typically, retention ponds are found in housing and commercial developments that were built in wetlands or wet areas. They are dug to accept the nutrient and pollutant laden water that drains from paved roads and yards of the development to prevent deterioration of "downstream" natural lakes and rivers.

Real Estate Lake

Real estate lakes Pits and depressions that remain after mining for fill dirt are turned into lakes and surrounded by homes.The dirt is dug to create higher land sites for homes and businesses to be built in naturally low areas. Florida has more real estates lakes than any other state in the nation.

Watershed
The watershed includes the land surrounding a lake that sheds water into the lake. Some lakes have very small watersheds, such as lakes on top of hills; some have very large watersheds, such as lakes in low areas surrounded by hills, and where water may drain into the lake from many square miles. Watershed delineation for Florida lakes is somewhat different from other parts of the country because of the state's high number of groundwater fed seepage lakes: in Florida, the aquifer watershed must also be taken into consideration.

Surface area
The surface area of a lake is the area covered by water today. Surface area is expressed in units of acres or hectares (ha). One hectare equals 2.47 acres.

Eighty percent of Florida's 8,000 lakes and ponds have a surface area of less than 100 acres (40 ha).

Thirty-one Florida lakes are greater than 5,000 acres (2,024 ha) in size.

Lake Okeechobee, by far the largest lake in Florida, and the second largest freshwater lake contained wholly within the United States, spans more than 450,000 acres (182,000 ha) of open lake and meandering shorelines of dense aquatic vegetation.

The surface area of a lake can change from year to year, and even during a single year, as drought and rain conditions alter the volume of water within the lake. Lakes with greater surface areas have more room for aquatic plants and therefore often are more costly to manage.

Volume and Depth
In general, Florida's lakes are shallow and tend to have less volume than the deeper lakes of the northern U.S. Studies have shown that shallow lakes are more susceptible to disruption of bottom sediments, especially along the shoreline; shallow southern lakes have warmer water and greater turnover (resulting in less temperature stratification); and our shallow lakes are more biologically productive (support more plants and animals) than do deeper lakes.

The total amount of water in a lake basin, its volume, is expressed in units of acre-feet or cubic meters. The volume of water in a lake may be estimated by multiplying the lake's surface area by its mean depth: V= mean depth X surface area. The mean depth can be found by measuring water depth in several locations throughout the lake water body and then finding the average measurement.

Shoreline and plant zonation

 

Read "The Revitalization of Lake Okeechobee" (PDF 1.93 MB), by the South Florida Water Management District.

The shoreline is where the water meets the land. On a bathymetric map (a map like the one above that shows a lake's contours and depths), the shoreline is the outermost contour line. Most lake vegetation grows along the shoreline, and may form "zones" of plant types, from plants that require various water depths to plants that require or tolerate occasional dry conditions. As the shoreline changes according to seasonal and yearly water level fluctuations, plants within the lake are directly affected - plant species and plant zonation may change according to plant ability to withstand inundation and/or drought.

There are four basic trophic states, and of course many states in between them:

Eutrophic lakes generally have high levels of nutrients and organic material, low levels of dissolved oxygen, and water that is green with algae. Hypereutrophic lakes are ones that are especially eutrophic.

Oligotrophic lakes generally have low levels of nutrients, sparse organic material, high dissolved oxygen levels, and very clear water. Newly formed lakes begin as oligotrophic.

Mesotrophic lakes are moderately enriched with nutrients and organic material.

A lake's trophic state affects its biological productivity. Eutrophic lakes generally have high concentrations of algae, vegetation and animals; eutrophic lakes are biologically very productive. On the other hand, oligotrophic lakes may have greater diversity of smaller organisms, but otherwise be biologically very unproductive. Plant and animal populations are directly affected by a lake's trophic state. Changes in trophic status can dramatically affect the species that depend on the lake habitat.

For more information on the trophic states of Florida's waterbodies, go to this page on our web site.

The rate of water inflow and outflow of a lake has a direct effect on the lake's water quality because inflow and outflow determine the "loads" of nutrients, minerals and pollutants present in the lake. These rates can be influenced by water control structures that decrease or increase the flow of water in and out of a lake system.

Sometimes lake water quality is erroneously judged on the basis of clarity. However, acceptable water quality in a lake is directly related to its management objectives and may have nothing to do with water clarity. For example, lakes intended for fishing will have higher nutrient content, thus greener water and many plants, whereas recreational lakes in which swimming and skiing are the most common use are expected to have clearer water and sandy beaches. For more information on water clarity, go to this page on our web site.

Rainfall is perhaps the most important factor that directly influences lake water level fluctuations. Drainage lakes are directly affected as rain accumulates on the surface and drains into the waterbody. Seepage lakes are also affected as rainwater is the primary source for groundwater recharge.

The watershed's surface water also affects lake water level fluctuations both naturally and artificially. Surface water flows overland and drains into drainage lakes either directly or through contributing streams, rivers, or other ponds and lakes. Surface water is also artificially directed to lake bodies by canals, pipes, culverts and storm sewers.

Groundwater exchange between a lake and its underlying aquifer can affect lake level water fluctuations. A decline in the water table (aquifer level) results in a decline in the amount of groundwater that feeds a seepage lake.

Evaporation causes lake levels to decline. Long periods of drought result in high lake evaporation and decreased water levels. Water evaporates from an open water body at about 6 inches per month during a typical Florida summer month. Plants also help reduce lake water levels through evapotranspiration - dense plant stands may transpire several inches of water a day. The effects of low rainfall are most noticeable in seepage lakes because evaporation is the primary method of water output and the water does not drain into surrounding areas. Evaporation is less noticable in drainage lakes because drainage lakes lose water primarily through the much quicker process of drainage outflow.

Human activities can dramatically affect lake water levels throughout the state. Because fluctuating water tables can create economic problems for land development, most of Florida's lakes have been physically altered to decrease flooding potential and/or increase drainage potential. Dams, weirs, canals, dykes, culverts and other such water control structures are used to artificially control lake water levels.

LAKE WILDLIFE
Lakes provide important habitats for alligators, fish, turtles, amphibians, birds, mammals, and snakes.

SOME NATIVE AQUATIC PLANTS
IN FLORIDA LAKES

Illinois pondweed	maidencane	yellow-eyed grass	fanwort	pickerelweed

giant bulrush	water shield	lake hygrophila	yellow water lily	lipocarpha

Here is an overview of native plants in Florida.

Here are pictures and line drawings of many aquatic plants in Florida.

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On the other hand, plant overpopulation from non-native invasive plants in a lake system impedes intended uses and creates problems for the humans and animals that use them.

SOME NON-NATIVE INVASIVE AQUATIC PLANTS
IN FLORIDA LAKES

water hyacinth	hydrilla	torpedo grass	water lettuce	water fern

Here is an overview of non-native plants in Florida.

Here are pictures and line drawings of many non-native plants in Florida.

Hydrilla, water lettuce, and water hyacinth are the primary plants managed in Florida's lake ecosystems. These plants are problematic in many of our lakes, often preventing navigation, fishing, and swimming, and crowding out native species and altering lake water quality.

Native nuisance plants
When lakes are seriously disturbed, a few native plant species, such as cattail (Typha sp.) can overpopulate and crowd out other desirable native plant species. Such single species monocultures can dramatically impact native wildlife and fish populations. Overpopulation can also disrupt human activities such as recreation, fishing, navigation, and water management. When necessary, native plant management is conducted similarly to invasive plant management, employing a variety of control methods that are appropriate to the nuisance plant, lake ecology, and environment.

Floating islands of plants and sediments (tussocks) occur in many Florida waterbodies, including lakes. These free-floating mats of aquatic vegetation, sometimes with organic sediments 1-3 feet thick, drift with the current and can impede navigation and recreation and obstruct crucial water flow. Less developed tussocks can be broken up with herbicides. However, older tussocks are more difficult to manage chemically as herbicides tend to merely defoliate the plants which in turn quickly regenerate from the rootstock. Therefore, mechanical controls such as shredders, draglines and harvesters are employed to physically destroy or otherwise remove vegetative islands from the lake waterbody.

Algae blooms
Nutrient loading, high temperatures and other changes in a lake's ecosystem can lead to an overproduction of algae. Algae blooms can result in a decreased level of dissolved oxygen in the water, fish kills, odor problems, bacterial contamination and recreational impairment. For more information about algae and algae blooms, go to this page on our web site.

Here is the DEP's official philosophical/operational statement regarding the management of non-native aquatic plants in Florida.

Some of the goals of aquatic plant management for Florida lakes include:

to preserve healthy habitats for native fish, wildlife, and plants

to maintain lake functions for flood protection

to ensure healthy water supply

to enable navigation, recreation, fishing, and other human necessities and pleasures

Machine removing plants	Water hyacinth weevil	Applying aquatic herbicide

Plant destroying and harvesting machines (as described on our mechanical controls page) can provide immediate relief for clogged lakes by cutting boat trails and clearing fishing areas. However, harvesters are expensive to operate, work slowly and are restricted to deeper waters. Sterile grass carp, a fish, as well as certain non-native plant-eating insects (as described on our biological controls page) are animals that are used as "biocontrols" for nuisance lake plants. However, grass carp must be confined, which is difficult to do in lakes that are connected to one another for flood control, and insect populations are often difficult to establish and proliferate. The most cost-effective and most used means of aquatic weed control in Florida lakes is the use of herbicides (as described on our herbicidal controls page).

First, managers must consider the "management objectives" for the lake; that is, whether the lake is to be managed as a recreation lake or a wild lake, a fishing lake or a hunting lake, an irrigation source or a potable water supply, or some combination of these and other uses.

Second, managers must consider the traits of the lake system; traits such as its watershed, its trophic state, its flow, its water chemistry and sediment composition, its size and depth, the type and abundance of plants, etc.

When necessary, aquatic plant control is coordinated and performed by:

Florida Department of Environmental Protection

water management districts,

counties and cities,

independent contractors and

the Army Corps of Engineers.

See a list of agencies involved on this page of our web site.

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When lakes are listed as "sovereignty submerged state lands", nuisance native and invasive exotic plant management is funded and contracted by the Florida Department of Environmental Protection.

Here is a clickable map of public waters by county

that qualify for management cost reimbursement from the state of Florida. In 2004, the Bureau of Invasive Plant Management contracted and reimbursed more than $21 million for plant management.

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It is estimated that the current, increasing bill for aquatic plant management in Florida is about $75 million per year.

Surface water runoff transports sediments and pollutants such as chemicals and nutrients that may have detrimental effects on the lake ecosystem. Surrounding land use determines the kind and quantity of substances that are carried into a lake system. Parking lots, septic systems, lawns, and agricultural and industrial effluent contribute to lake water pollution.

Low water levels from excessive water consumption affects some seepage lakes that are fed by groundwater resources.

Alteration from poorly constructed water management projects from the past and present can result in unhealthy lake environments that contribute to overgrowth of invasive or native species, odor, stagnation, low oxygen levels, etc.

Acid rainfall can alter the water quality of a lake and cause dramatic changes in the ecosystem. Although many of the state's lakes are naturally acidic (pH 5.8 to 7.8), several Florida lakes, especially in northern Florida, have soft water and are highly susceptible to the effects of acidic rain.

Algae blooms occur primarily in response to nutrient loading from the surrounding watershed. The blooms prevent light from reaching submersed plants, decrease oxygen supply of the water, and reduce water clarity. For more information about algae blooms, go to this page on our web site.

Diverting or sequestering nutrients from running into public lakes.

Aeration fountains and bubblers add oxygen to lake water in order to reduce fish kills, algae blooms and phosphorus mobility.

Pretreatment of stormwater in retention ponds allows settlement of contaminants and debris prior to releasing the water into the lake ecosystem. Sometimes stormwater is treated with alum, a compound that quickly inactivates contaminants and enables the material to be removed from the water once it sinks to the bottom.

Dredging of lake sediments (muck), primarily organic debris, increases lake depth, removes nutrients from the water and enhances bird and fish use. Learn about the Lake Tohopekaliga muck removal project on this page of our web site.

Public education of taxpaying homeowners by government agencies and public advocacy groups encourages residents to practice lake-friendly habits such as leaving aquatic vegetation on the shore line and reducing fertilizer use.

LAKEWATCH is a special program in Florida in which several hundred citizen groups voluntarily monitor their lakes and send water samples, plant samples and other data to the University of Florida for analysis. In return, the Department of Fisheries and Aquatic Sciences sends the citizen groups reports about their lakes. To learn more about this exceptional program, contact LAKEWATCH here.

For information on what you can do to conserve Florida's waters, go to this page on our web site.

Visit the Florida Atlas of Lakes web site which highlights the critical lake water resources in Florida and demonstrates the value of Florida’s many lake volunteers.