Minimum Flows and Minimum Water Levels Frequently Asked Questions

What are minimum flows and minimum water levels (MFLs)?

In short, an MFL sets a limit on how much water can be withdrawn from various water resources to prevent significant harm occurring to those resources or the ecology of the area.

What does “significant harm” mean?

The Florida legislature did not define the term ‘significant harm.’ However, the District has developed criteria for significant harm to various types of water resources. The criteria are based on environmental changes resulting from variances in water flows or levels. Their use for setting MFLs has been reviewed and accepted by numerous panels of independent scientists.

Why does the Southwest Florida Water Management District establish MFLs?

Section 373.042 of the Florida Statutes requires the state water management districts or the Florida Department of Environmental Protection to establish MFLs.

With so many waterways in the District, how does the District prioritize which MFLs to set?

The District maintains and updates a priority list and schedule for the establishment of MFLs within its boundaries. This list and schedule is reviewed and, if necessary, revised annually as required by the Florida Statutes. Each year the District seeks public input about the order in which MFLs will be established for lakes, wetlands, rivers, streams and aquifers The current priority list and schedule is available from the District’s Minimum Flows and Levels Documents and Reports webpage at

How are MFLs determined?

District scientists and engineers consider how wetlands, lakes, rivers, estuaries, and aquifers adjust to changes in hydrologic conditions. For each priority water body, the District studies and collects a large amount of information such as historical water levels and flow rates, vegetation data, water quality data, wildlife variety and abundances, and other pertinent information. As each natural system is unique, the District and other experts in the field have developed methods for setting MFLs using the best available information, which typically  includes extensive data sets and advanced computer models.

Does anyone besides District staff get to review a proposed MFL before it is set?

Yes, an essential component of the process includes the District’s voluntary use of peer review which involves review and comment on a  proposed MFL and the data and methods used for its development by an independent panel of scientists. Other local, state and federal agencies and the public also have opportunities to review and comment on a proposed MFL. A public meeting is facilitated to explain the proposed MFL and to allow for public comment. These comments are read and considered by staff before making a recommendation to the District’s 13-member Governing Board regarding the adoption of a proposed MFL. Staff recommendations concerning MFLs are considered by the Board at publicly noticed Board meetings that provide another opportunity for public input.

Who gives the final approval for an MFL?

The District’s 13-member Governing Board approves MFLs through a vote. The Board is provided all external comments to review in advance of receiving a presentation from District staff on the proposed MFL. If the Governing Board votes to adopt an MFL, it is adopted into District Rules (Chapter 40D-8, Florida Administrative Code).

How does the Southwest Florida Water Management District use MFLs?

MFLs are used by the District to plan for current and future regional water needs, which may include the need to offset groundwater use through projects that encourage conservation and provide alternative water supplies. MFLs also are an important tool for the District’s water use and environmental permitting programs to ensure that withdrawals do not exceed an established MFL and cause significant harm to the water resources or ecology of the area.

Does an MFL allow the withdrawal of water from the aquifer or other water bodies?

No, an MFL does not authorize the withdrawal of water. Anyone wanting to withdraw quantities of water that requires a water use permit must still follow the proper procedures for permit issuance. District staff consider established MFLs as part of the decision-making process when reviewing permit applications. This often includes running computer models to evaluate the effects of proposed withdrawals. For an applicant to obtain a water use permit, the effect of proposed withdrawals must consider MFLs.

What are the District’s requirements to obtain a permit to withdraw water?

Three primary criteria (defined by Section 373.223 of the Florida Statutes) must be satisfied before obtaining a permit from the District. The proposed water use must:

  1. Be reasonable and beneficial,
  2. Not interfere with any existing legal use of water, and
  3. Be consistent with the public interest.

In addition, the proposed withdrawal, combined with other withdrawals, must not cause adverse impacts to the environment, including exceeding an established MFL.

Can the withdrawal of water be permitted from a waterbody that does not have an established MFL?

Yes, provided the permit applicant meets all requirements for the issuance of a water use permit.

What happens if MFLs are not being met?

A recovery strategy is implemented if an MFL is not currently met. A prevention strategy is implemented if an MFL is projected to not be met in the next 20 years. Prevention and recovery strategies allow for providing sufficient water supplies for all existing and projected water uses through development of additional water supplies, implementation of conservation and efficiency measures, and regulatory measures. The District funds the initiatives associated with prevention and recovery strategies with help from local governments and regional water supply authorities. The intent of these strategies is to achieve recovery to the established MFL as soon as possible or prevent the existing flow or water level from falling below the established MFL.

Are MFLs ever reevaluated?

Yes, MFLs are reevaluated periodically when District staff determines it is necessary, and some MFLs have specific timeframes for reevaluation that were established by the District’s Governing Board. The District always uses the best available science in its decision-making. However, we recognize that our scientific knowledge will continue to grow over time. Reevaluating an MFL allows the use of updated data, the latest computer models and other analytical tools to assess and revise, if necessary, an MFL that was previously established.