J U N E 2 0 1 3 Restoration Strategies Program Science Plan for the Everglades STAs EXECUTIVE SUMMARY In June 2012, the State of Florida and the U.S. Environmental Protection Agency (USEPA) reached consensus on new restoration strategies for further improving water quality in the Everglades. Based on months of scientific and technical discussions, these strategies will expand water quality improvement projects to achieve an ultra-low total phosphorus (TP) water quality standard established for the Everglades. Under these strategies, the South Florida Water Management District (SFWMD or District) is implementing a technical plan, as documented in the Restoration Strategies Regional Water Quality Plan (SFWMD, 2012a), to complete six water treatment and storage projects in three flow paths between Lake Okeechobee and the greater Everglades—including more than 6,500 acres of new Everglades Stormwater Treatment Areas (STAs). The technical plan also calls for 110,000 acre-feet of additional water storage through construction of Flow Equalization Basins (FEBs) to capture runoff during storm events and provide a more steady flow of water to the STAs, helping to maintain desired water levels needed to achieve optimal water quality performance. Design and construction of the treatment and storage projects is scheduled to be accomplished in three phases over a 12-year timeframe, with completion set for 2025. Collectively, these projects are part of a revised National Pollutant Discharge Elimination System (NPDES) watershed permit issued by the Florida Department of Environmental Protection (FDEP) and approved by the USEPA for operation of the five existing Everglades STAs (STA-1 East, STA-1 West, STA-2, STA-3/4, and STA-5/6) which total approximately 57,000 acres. The NPDES permit along with a new state-issued Everglades Forever Act (EFA) watershed permit establishes stringent TP limits—Water Quality Based Effluent Limit, or WQBEL—for water discharged into the Everglades Protection Area. The NPDES and EFA watershed permits and associated Consent Orders also require that the District develops and implements a science plan to enhance the understanding of mechanisms and factors that affect phosphorus treatment performance, particularly those that are key drivers to performance at low TP concentrations (<20 micrograms per liter, or μg/L). Issues identified for potential study investigation include the effects of microbial activity, phosphorus flux, inflow volumes and timing, inflow phosphorus loading rate and concentrations on phosphorus outflow, phosphorus removal by specific vegetation, and the stability of accreted phosphorus. The Science Plan for the Everglades Stormwater Treatment Areas was structured and developed around six key questions, and related sub-questions, that were identified by the District’s Science Plan Team. The effort involved reviewing existing knowledge, determining information gaps, and formulating questions regarding phosphorus removal mechanisms and the factors that influence these mechanisms, including physical, chemical, and biological processes. A list of key questions related to the science, operation, and engineering aspects of STA performance was then developed. Analyses of each individual STA was also performed to determine factors affecting phosphorus removal performance, identify areas for further investigation, and list potential engineering refinements for implementation. Overall, the Science Plan has been developed collaboratively and in consultation with interagency Technical Representatives and scientific experts from the U.S. Environmental Protection Agency, U.S. Department of Interior, U.S. Army Corps of Engineers and FDEP. This plan is intended to be a strategic, high-level document that will be revised and updated as needed. Specific implementation of science activities and research studies will be guided by the Five-Year Work Plan, which is currently comprised of nine proposed, initial study plans. Results from the Science Plan studies could be used to inform the design and operations of water quality projects, which will ultimately improve capabilities to manage for achievement of the WQBEL. Related data and information gathered from these studies will also be incorporated into the development and refinement of the District’s modeling tools. Further information on Restoration Strategies Program including the Science Plan is available at www.sfwmd.gov/restorationstrategies. 1 Science Plan for the Everglades STAs Restoration Strategies Program 1. INTRODUCTION In accordance with the Everglades Water Quality Restoration Framework Agreement between the U.S. Environmental Protection Agency (USEPA), Region IV, and Florida Department of Environmental Protection (FDEP), dated June 12, 2012 (FDEP and USEPA, 2012) (Appendix A) and the Restoration Strategies Regional Water Quality Plan (SFWMD, 2012a), the Science Plan for the Everglades Stormwater Treatment Areas (STAs) has been established to investigate the critical factors that collectively influence the total phosphorus (TP) reduction and treatment performance in the STAs. Key topics associated with the scientific investigations covered in this Science Plan include the effects of microbial activity, phosphorus (P) flux, inflow volumes and timing, inflow phosphorus loading rate and concentrations on phosphorus outflow, phosphorus removal by specific vegetation, and stability of accreted phosphorus. It is expected that the results from these studies will be used to enhance the design and operations of projects under the Restoration Strategies (RS) Program, which will ultimately improve capabilities of the STAs to achieve compliance with the state’s water quality criteria for TP. This Science Plan is also intended to fulfill the requirements of the Consent Orders between the FDEP and the South Florida Water Management District (SFWMD or District) (dated August 15, 2012) associated with the National Pollutant Discharge Elimination System (NPDES) Watershed Permits and Everglades Forever Act (EFA) Watershed Permits for the Everglades STAs (OGC Nos. 12-1148 and 12-1149, respectively), issued on September 10, 2012 (Appendix A). Pursuant to the Consent Orders, this plan has been developed in consultation with representatives designated by the FDEP and USEPA, on behalf of the state and federal agencies, respectively. 1.1 BACKGROUND As set forth in the 1994 Everglades Forever Act, Section 373.4592, Florida Statutes, and the 1992 Consent Decree entered in the case United States v. South Florida Water Management District, Case No. 88-1886-CIV-Moreno (S.D. Fla.), reducing TP levels in the Everglades Protection Area (EPA) would be achieved by a two pronged approach comprised of building STAs and implementing a regulatory agricultural Best Management Practices (BMPs) program in the Everglades Agricultural Area (EAA). With regard to the Everglades STAs, in 1992, the plan contemplated the construction of four STAs comprised of 35,000 acres. In 1995, the plan was expanded by 5,000 acres and reconfigured into six STAs (STA-1W, STA-1E, STA-2, STA-3/4, STA-5, and STA-6). By 2006, however, it became apparent that additional STA acreage was needed and, therefore, STA-2, STA-5, and STA-6 were expanded. As of 2010, approximately 57,000 acres of STAs were built and flow capable. In September 2010, in a related federal court lawsuit between the Miccosukee Tribe and the USEPA and FDEP, the USEPA issued an Amended Determination in which the agency proposed a new Water Quality Based Effluent Limit (WQBEL) for the Everglades STAs—designed to achieve compliance with Florida’s phosphorus water quality standard—and an STA expansion of 38,000 acres to achieve this limit. The Amended Determination, however, invited the District to submit a counter proposal. 1.2 RESTORATION STRATEGIES PROGRAM OVERVIEW In early 2010, the SFWMD, State of Florida, and USEPA began technical discussions to establish a Water Quality Based Effluent Limit (WQBEL) for TP in discharges from the Everglades STAs (SFWMD, 2012b) that would achieve compliance with state’s numeric TP criterion in the EPA and to identify a suite of additional water quality projects to work in conjunction with existing STAs to meet the WQBEL. From these discussions, in 2012, the FDEP issued a National Pollutant Discharge Elimination System (NPDES) Watershed Permit and an associated Consent Order (FDEP, 2012a) and an EFA Watershed Permit and associated Consent 2 Restoration Strategies Program Science Plan for the Everglades STAs Order (FDEP, 2012b) (see Appendix A, respectively), establishing the WQBEL and suite of water quality improvement projects to be constructed under the Restoration Strategies Program. Overall, the planned strategies outlined in the permits and associated Consent Orders are intended to expand water quality improvement projects to achieve the phosphorus water quality standard established for the Everglades. Under these strategies, the SFWMD is implementing a technical plan to complete six projects that will create more than 6,500 acres of new STAs and 110,000 acre-feet (ac-ft) of additional water storage by constructing Flow Equalization Basins (FEBs). The strategies also include additional sub-regional source controls in areas of the eastern EAA where TP levels in stormwater runoff have been historically higher. A robust science plan will ensure continued research and monitoring to improve and optimize the performance of water quality treatment technologies. Design and construction of the treatment and storage