Requirements for minimum flows and levels for Florida's water bodies prevent significant harm by permitted water withdrawals.
One of the ways in which the South Florida Water Management District is working to protect and conserve Florida's water resources is through the minimum flows and levels (MFLs) program. Establishing MFLs is an important step in the District's work of planning for adequate water supplies while also protecting water resources from significant harm. In South Florida, minimum levels have been established for lakes, wetlands and aquifers. Minimum flows have been set for rivers, streams and estuaries.
MFLs are defined as the minimum water levels and/or flows, adopted by the District Governing Board, required to prevent significant harm to the water resources resulting from water withdrawals that are permitted by the District. MFLs define how often and for how long high, average and low water levels and/or flows should occur to prevent significant harm. When use of water resources alter the water levels below the defined MFLs, significant ecological harm can occur.
Establishing MFLs for all of South Florida is an ongoing effort. The Priority Water Body List and Schedule is submitted annually to the Florida Department of Environmental Protection. The District publishes a draft technical document summarizing the methods, models and data that provide the MFLs scientific basis. This document is then subject to scientific peer review by an independent panel of experts. It also includes a series of public rule development workshops that allow interested stakeholders opportunities to provide comments on the draft technical document and proposed draft rule language prior to Governing Board approval and incorporation into District rules. The MFL is then implemented through the District's consumptive use permitting and water supply planning program.
The South Florida Water Management District held a two-day science symposium in Fort Myers to present and receive technical comments on recently completed studies assessing the responses of a suite of ecological indicators in the Caloosahatchee River Estuary to low freshwater inflows in the dry season.
MFLs are established to protect water resources from significant harm resulting from permitted water withdrawals. Establishing MFLs is a requirement of the state Legislature under Subsection 373.042(2), Florida Statutes (F.S.). In addition, establishing MFLs is required by the state Comprehensive Plan, the water resources implementation rule (formerly state water policy) and a 1996 Governor's executive order for priority water bodies.
MFLs identify a range of water levels and/or flows above which water could be permitted for consumptive use. The MFLs program supports the District's regional water supply planning process (section 373.0361, F.S.); permitting criteria for the consumptive use permitting program (Chapter 40C-2, F.A.C.); and the environmental resource permitting (ERP) program.
In addition, MFLs protect nonconsumptive uses of water. Nonconsumptive uses include quantities of water necessary for navigation and recreation and for fish and wildlife habitat.
Florida law states that the District's Governing Board "shall use the best information and methods available to establish limits which prevent significant harm to the water resources or ecology." MFLs are determined based on evaluations of topography, soils and vegetation data collected within plant communities and other pertinent information associated with the water resource.
MFLs take into account the ability of wetlands and aquatic communities to adjust to changes in hydrologic conditions. MFLs allow for an acceptable level of change to occur. When use of water resources shifts the hydrologic conditions below levels defined by MFLs, significant ecological harm can occur.
MFLs are adopted as water management district rules (Chapter 40E-8, Florida Administrative Code) by the governing boards of the water management districts. This is a public process that involves documenting the scientific and technical information that supports the MFL, peer review of that information and public workshops. The MFL is then reviewed by the Florida Department of Environmental Protection, then adopted by the District and published in the Florida Administrative Weekly. MFLs are to be reviewed periodically and revised as necessary per Subsection 373.0421(3), F.S.
MFLs apply to decisions affecting permit applications, declarations of water shortages and assessments of water supply sources. Computer simulation models for surface and groundwaters are used to evaluate the effects of existing and/or proposed consumptive uses and the likelihood they might cause significant harm. The District's Governing Board is required to develop recovery or prevention strategies in those cases where a water body currently does not or will not meet an established MFL. Water uses cannot be permitted that cause any MFL to be violated. Specific recovery or prevention strategies are found in the regional water supply plans and in the District's MFL technical publications.
Related Documents – MFL Rule Development Supporting Documentation
Lake Okeechobee, Northern Biscayne Aquifer and the Everglades