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Minimum Flows and Levels FAQ

Do you have questions about minimum flows and levels or questions about Florida's rivers and floodplains? Read the FAQ article for answers.

Minimum flows and levels, or MFL, are the lowest water flows and water levels that can occur in a Florida water body. Water flows and water reductions below the minimum levels could be significantly harmful to the water resources or ecology of the area

The five Florida water management districts are responsible for MFL development for each water body within their boundaries (Florida Statute 373.042).

Each water management district has different methods and protocols it uses to set MFL. All water management districts use the best available information and consider the natural processes and uses of the water body. Considerations include fish and wildlife habitats, maintenance of freshwater storage and supply, water quality, and recreation (Florida Administrative Code 62-40.473). Computer simulations are done to identify a range of flows or levels above which water may be permitted for consumptive use, such as for drinking water or irrigation.

Once MFL are reached, the water management district may restrict water consumption in the area.

To provide water management districts with necessary biological data, the agency's biologists research relationships between river flows and levels and fish and invertebrate communities.

A floodplain is a flat tract of land that borders a stream or river and is susceptible to flooding during times of high water.

Floodplain inundation occurs when the river overflows its banks and submerges the flat expanses of land next to the riverbank. The periodicity (or frequency), duration, and extent of that inundation vary based on the characteristics of the flood event, the height of the water table, and the season.

Floodplain inundation provides a link for exchange of important materials, such as nutrients and organic material, between land and aquatic environments. When the floodplain becomes inundated, the amount of food and habitat available for aquatic organisms, like fish and invertebrates, increases. During extreme high water periods, dead plant material and woody debris are also removed and forced down river, which re-opens up these floodplain areas and creates new snag habitat down river.

When a river overflows its banks, the floodwater links the floodplain and river ecosystems. This link, or connectivity, allows nutrients and resources to transfer between the floodplain and the river areas.

"Bankfull" is a term that refers to a stream or river that has water at the top of its banks. When a river or stream is "bankfull," a heavy rain event will likely cause water to flow into the floodplain.