District uses minimum flows and levels to help protect water bodies

May 6, 2021

Stephen Jennewein conducts a survey of vegetation

District Environmental Scientist Stephen Jennewein conducts a survey of vegetation along the Wekiva River.

The St. Johns River Water Management District uses a wide variety of tools to help protect water resources in our 18-county region, including the highly technical process to establish minimum flows and levels — or MFLs.

As part of our core missions of water supply and natural systems, Florida law guides the work required to set MFLs for priority water bodies. These MFLs define the limits for a water body at which further water withdrawals would be significantly harmful to the water resources or ecology of an area, adding to the resiliency of our waterways. Our Governing Board must approve MFLs and members receive regular updates from staff on the complex work that goes into these protective measures that have far-reaching benefits for people and our waterways.

A Priority List and Schedule is submitted to the Florida Department of Environmental Protection each year and included in the District’s Consolidated Annual Report once approved (and published by March 1 yearly).

Since the mid-1980s, the District has set MFLs for lakes, rivers, wetlands and each of our Outstanding Florida Springs. Determining or re-evaluating an MFL is complex and it doesn’t happen overnight. Field-based environmental assessments and scientific literature are the basis for each MFL determination in a process that takes many months or years to complete to ensure accuracy.

For each MFL, the District collects and analyzes large amounts of information, including historical water levels or flow rates, water quality data, and wetland vegetation data. Sophisticated hydrologic, hydraulic and groundwater and surface water modeling is also conducted as part of the MFLs determination and assessment process.

Many factors are studied and tailored for each unique water body. These values may include the habitat needed for the many native plant and animal species within our District, as well as the many human uses of water such as navigation, recreation and aesthetics.

The cyclical rise and fall of water bodies is a natural phenomenon, with each water body needing a certain amount of water to properly function and retain its water resource values. This is important to know for our work and critical for areas such as our Regulatory Services division tasked with determining the amount of water that a public utility can withdraw without causing harm to a nearby spring or the volume of water an agricultural operation can draw from a lake without causing environmental harm to that lake.

Our District scientists are dedicated to the data-driven, in-depth work necessary to set MFLs and revisiting them regularly to ensure Florida’s water resources are protected from significant harm.  On Tuesday, May 11, our Governing Board will hold a public hearing to consider adoption of proposed rules to amend MFLs for Lakes Brooklyn and Geneva in Bradford and Clay counties. We encourage you to visit www.sjrwmd.com/streamlines/finding-a-balance-in-floridas-waters-the-minimum-flows-and-levels-program to learn more about the process.

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