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Water supply

The St. Johns River Water Supply Impact Study
Final report

The St. Johns River Water Supply Impact Study — the most comprehensive and scientifically rigorous analysis of the St. Johns River ever conducted — was completed and presented to the St. Johns River Water Management District’s Governing Board on Feb. 14, 2012.

The four-year study resulted in the development of tools that will help guide future decision-making on the potential environmental effects of proposed water withdrawals from the St. Johns and Ocklawaha rivers on the St. Johns River system. The state-of-the-art models and methodologies that resulted from the study will be used in consumptive use permitting, minimum flows and levels development, regional water projects and water supply planning.

As part of the WSIS, scientists collected environmental data from the St. Johns River, including this work at Lake Monroe to collect data on plankton.

The tools developed will be applied during the review process for any future river withdrawal permit applications. The amount of water that may ultimately be withdrawn will depend on the proposed location, design and timing of proposed withdrawals, as well as the numerous permitting criteria considered when permit applications are submitted.

The tools also can be used by the district, local governments, other agencies, and potentially with other river systems.

The study confirms the findings of earlier investigations indicating that the St. Johns River can be used as an alternative water supply source without causing significant harm to the environment. The study does not authorize river water withdrawals.

More than 70 scientists and engineers – a combination of District staff and outside experts – have been involved in the study that began in December 2007. Experts analyzed a range of water withdrawal scenarios that are representative of potential future water withdrawals. Thousands of different combinations were evaluated.

Among results of the WSIS are state-of-the-art computer models.

The district also engaged one of the nation’s most highly respected bodies of scientists, the National Academy of Sciences, to conduct an impartial peer review of the project. The National Research Council, the Academies’ operating arm, completed its peer review in December.

The St. Johns and Ocklawaha rivers are being considered for future water supplies because groundwater supplies are limited in many areas of the district. Because the traditional water source — groundwater from the Floridan aquifer — is limited, additional water conservation and alternative water supplies continue to be high priorities. Those alternative water supplies include reclaimed water, brackish groundwater, seawater and surface water such as the Ocklawaha and St. Johns rivers.

Accessing this report

The WSIS is available only as an electronic document, with separate portable document format (PDF) files for each chapter and appendixes. Following is the list of each chapter and the appendixes. To download a file to your computer, right click on the desired link below and choose “Save Target As…” from the resulting pop-up menu. You will be prompted to choose a location on your computer to save the file.

Water Supply Impact Study

  • The Report (July 23, 2012)


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St. Johns River Water Management District
4049 Reid Street, Palatka, FL 32177
(800) 725-5922