Two waterbody classification systems in Florida provide insight into the degree that a waterbody may support aquatic plants, and the strategies that might be considered when developing aquatic plant management programs. Trophic state is an indication of the level of nutrients in a waterbody and the amount of biological activity (growth) that the waterbody can sustain. Additionally, Florida’s surface water classification system groups waters according to their designated uses, arranged in order of the degree of protection required.
The trophic state of a waterbody is generally reported as a combination of four parameters: the levels of available nutrients, nitrogen and phosphorus; the amount of free-floating algae (as determined by chlorophyll in the water column); and water clarity. Below, are descriptions of the four trophic states.
An oligotrophic lake has low primary productivity as a result of low nutrient content. These lakes have low algal production, and consequently often have very clear waters with high drinking-water quality. They have few aquatic plants, few fish, not much wildlife, and a sandy bottom. Examples in Florida are the sandhill lakes of the Lake Wales Ridge and the coastal dune lakes in the Florida panhandle.
Mesotrophic lakes have an intermediate level of productivity. These lakes are commonly clear water lakes and ponds with beds of submerged aquatic plants and medium levels of nutrients. Most natural lakes in Florida are mesotrophic or slightly eutrophic.
A eutrophic body of water has high biological productivity due to excessive nutrients, especially nitrogen and phosphorus. Eutrophic waters support an abundance of aquatic plants or algae and have the potential to support a lot of fish and wildlife. When aquatic plants are dominant, the water tends to be clear. When algae are dominant, the water tends to be darker or greener. Occasional algal blooms may occur resulting in fish kills due to oxygen consumption via algal respiration and bottom-living bacteria. The process of eutrophication can occur both naturally and by human impact on the environment.
Hypereutrophic lakes are highly nutrient-rich lakes characterized by very low water clarity. High algal levels may block light and prevent (or hinder) submersed plant growth. Frequent and severe algal blooms can significantly reduce oxygen levels and prevent life from functioning at lower depths where mixing of the water cannot occur. Lakes Apopka (Orange Co.) and Hancock (Polk Co.) are examples of hypereutrophic Florida lakes.
Oligotrophic lakes rarely have aquatic plant problems and require little management. Since hypereutrophic lakes have such poor transparency, they do not usually support submersed plants. Even invasive species like hydrilla have difficulty establishing in a hypereutrophic lake. Floating invasive plants; however, can present serious management issues in hypereutrophic, eutrophic, and even mesotrophic waters due to nutrient availability in the water column. Shallow mesotrophic and eutrophic lakes, the most common in Florida, readily support floating, submersed, and emergent aquatic plants and are highly susceptible to invasive plant species.
Surface Water Classification
Florida surface waters are classified by the Florida Department of Environmental Protection (FDEP) in Section 62.302.400, Florida Administrative Code. These guidelines provide different water quality standards for five classes of waterbodies defined by their respective designated uses. Below are the classifications for surface water in the state of Florida:
- Class I Waters: Potable Water Supplies
- Class II Waters: Shellfish Propagation or Harvesting (generally coastal waters)
- Class III Waters: Fish Consumption; Recreation, Propagation and Maintenance of a Healthy, Well-Balanced Population of Fish and Wildlife
- Class III Waters (limited): Fish Consumption; Recreation or Limited Recreation; and/or Propagation and Maintenance of a Limited Population of Fish and Wildlife (see Rule 62-302.400, F.A.C.).
- Class IV Waters: Agricultural Water Supplies
- Class V Waters: Navigation, Utility, and Industrial Use
Thousands of miles of canals, and their water control structures, are carved into Florida's landscape, especially in the southeastern part of the state. Canals are artificial waterways that modify existing rivers or streams; or are dug into wetlands or uplands for navigation, drainage and flood control, irrigation, access, and recreation. Florida canals range from a few feet to hundreds of feet wide and from a few feet to as deep as 35 feet.
Visit the Canals page for more information.
Lakes and Ponds
Among the nearly 8,000 lakes in Florida are some of the most biologically rich systems in the world. Each lake 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 flat prairies, each plays crucial roles in irrigation, flood control, drinking water supply, recreation, navigation, and as habitats for plants and wildlife.
Nearly 1,700 rivers and streams stretch across the state. Ranging from a few feet to a couple of miles wide, these freshwater veins carve into the limestone bedrock, shaping Florida's distinctive karst topography. Florida rivers are the lifelines for many of the state's swamps, marshes, lagoons, and estuaries.
Visit the Rivers page for more information.
Springs and Aquifers
Springs represent major discharge areas, where groundwater is forced to the surface due to pressure from confining bed of impermeable sediments. Releasing eight billion gallons of freshwater each day, Florida has the most productive spring system in the world. Over 600 springs have been documented and geologists estimate that hundreds more are waiting to be discovered. The majority of Florida’s springs are found in central and north-central Florida—part of the Floridan aquifer system, one of five main aquifers in the state. These underground aquifers are the reservoirs for Florida's natural water filtration systems providing nearly 100% of the state's drinking water and more than 60% of the state's freshwater usage in agriculture and industry. Groundwater released from our aquifers, either through springs or man-made wells and pumping stations, sustains thousands of ecosystems and is an essential resource for human health, outdoor recreation, industry and agriculture.
Wetlands are the transition zones between dry upland ecosystems and deeper aquatic habitats. Nearly one-third of Florida’s wetlands are comprised of marsh ecosystems–delicate habitats possessing significant scientific, ecologic, and economic value. Other Florida wetlands include swamps, which can be described as wetlands with trees, having saturated soils and standing water for at least part of the year. A unique recipe of multiple groundwater sources, frequent natural fires, and flat karst topography allows Florida to have the most diverse mosaic of swamp habitats of any place in the world. Combined, these different types of wetlands are crucial for maintaining the health of many of Florida's aquatic ecosystems; they provide flood control, aquifer recharge, coastal protection, and they also act as "kidneys" that help filter pollutants from the ecosystem.