WATER RESOURCE AND HUMAN USE ASSESSMENT OF THE RAINBOW RIVER IN MARION COUNTY, FLORIDA (DRAFT) MAY 2009 Prepared for: Prepared by: HSW Engineering, Inc. 3820 Northdale Boulevard, Suite 210B Tampa, Florida 33624 Table of Contents Section Page 1.0 Introduction ............................................................................................................ 1-1 2.0 Data Summary........................................................................................................ 2-1 2.1 Well Stage................................................................................................ 2-3 2.2 Discharge................................................................................................. 2-5 2.3 Water Quality........................................................................................... 2-8 2.4 Sediment .................................................................................................. 2-8 2.5 Vegetation, Soils, and Transects.............................................................. 2-9 3.0 Minimum Flows and Levels Development............................................................. 3-1 4.0 Evaluation of Water Resource Values .................................................................... 4-1 4.1 WRV-1: Recreation In and On the Water...................................................... 4-1 4.2 WRV-2: Fish and Wildlife Habitats and the Passage of Fish........................ 4-10 4.2.1 Fisheries............................................................................................. 4-12 4.2.2 Floodplain Wetlands and Hydric Soils .............................................. 4-18 4.2.3 Usage of Floodplains by Wading Birds............................................. 4-20 4.2.4 Other Factors for Consideration......................................................... 4-21 4.2.5 Summary ........................................................................................... 4-21 4.3 WRV-3: Estuarine Resources ........................................................................ 4-25 4.4 WRV-4: Transfer of Detrital Material ........................................................... 4-26 4.5 WRV-5: Maintenance of Freshwater Storage and Supply............................. 4-31 4.6 WRV-6: Aesthetic and Scenic Attributes ...................................................... 4-35 4.7 WRV-7: Filtration and Absorption of Nutrients and Other Pollutants.......... 4-40 4.8 WRV-8: Sediment Loads............................................................................... 4-44 4.9 WRV-9: Water Quality.................................................................................. 4-51 4-10 WRV-10: Navigation..................................................................................... 4-57 5.0 Summary................................................................................................................. 5-1 All Figures 1-1 The Rainbow River located in Marion County, Florida ........................................ 1-1 1-2 Location of Rainbow River and Rainbow Springs ................................................. 1-3 1-3 Locations of spring vents in Rainbow Springs Complex........................................ 1-4 2-1 Overview of Rainbow River Watershed................................................................. 2-2 i Table of Contents (continued) Figures Page 2.1-1 Daily well stage (1965-2008) at USGS 290514082270701 Rainbow Springs Well near Dunnellon, FL ........................................................................................ 2-3 2.1-2 Daily water level elevation duration curve (1965-2008) at USGS 290514082270701 Rainbow Springs Well near Dunnellon, FL............................................................ 2-4 2.1-3 Monthly average water level elevation (1965-2008) at USGS 290514082270701 Rainbow Springs Well near Dunnellon, FL............................................................ 2-4 2.2-1 Daily average discharge at USGS 02313100 Rainbow Springs near Dunnellon, FL versus daily average well stage (1965-2008) at USGS 290514082270701 Rainbow Springs Well near Dunnellon, FL............................. 2-6 2.2-2 Baseline and historical daily average discharge (1965-2008) at USGS 02313100 Rainbow Springs near Dunnellon, FL ................................................... 2-6 2.2-3 Baseline and historical daily average discharge duration curve (1965-2008) at USGS 02313100 Rainbow Springs near Dunnellon, FL .................................... 2-7 2.2-4 Baseline (top 1965-2008) and historical (middle 1965-2008) monthly average flow at USGS 02313100 Rainbow Springs near Dunnellon, FL............................ 2-7 2.3-1 Water quality collection sites, Rainbow River, Marion County, Florida ............... 2-11 2.5-1 PHAB and vegetation transect lines, Rainbow River, Marion County, Florida..... 2-12 2.5-2 Transect locations and soils along the Rainbow River Study Corridor.................. 2-13 3-1 Low flow one-day duration frequency curves ........................................................ 3-6 3-2 High flow one-day duration frequency curves........................................................ 3-6 3-3 Change in one-day low flow events........................................................................ 3-7 3-4 Change in one-day high flow events....................................................................... 3-7 3-5 Relative change in one-day low flow events .......................................................... 3-8 3-6 Change in one-day high flow events ...................................................................... 3-8 4.1-1 Recreational area and activities in Rainbow Springs and River............................. 4-3 ii Table of Contents (continued) Figures Page 4.4-2 Vegetation cross-section VEG-7............................................................................. 4-28 4.4-3 Wetted perimeter versus elevation for cross-section VEG 7.................................. 4-28 4.5-1 Location map of CUP allocations near Rainbow River.......................................... 4-33 4.8-1 Sediment load classification categories .................................................................. 4-44 4.8-2 Hjulstrom’s chart of sediment zones....................................................................... 4-46 4.9-1 Secchi depth versus time (2002-2008) at the Rainbow River Head Springs.......... 4-53 4.9-2 Secchi depth at water quality station RR1 on the Rainbow River versus well stage (2002-2008) at USGS 290514082270701 Rainbow Springs Well near Dunnellon, FL ................................................................................................. 4-53 4.9-3 Secchi depth at water quality station RR9 on the Rainbow River versus well stage (2002-2008) at USGS 290514082270701 Rainbow Springs well near Dunnellon, FL ......................................................................................... 4-54 4.9-4 Total nitrogen versus time for 9 sampling locations on the Rainbow River .......... 4-54 All Tables 3.1 Hierarchical classifications for evaluating the WRVs for the Rainbow River ....... 3-9 4.1-1 Frequency and duration parameters for WRV-1 under baseline and MFL scenarios........................................................................................................ 4-7 4.2-1 Fish species occurring in the Rainbow River ......................................................... 4-13 4.2-2 Hydraulic depths and associated baseline flows at 47 HEC-RAS cross sections... 4-15 4.2-3 Frequency and duration parameters for WRV-2 under MFL scenarios ................. 4-17 4.2-4 Median elevation (ft-NGVD) of vegetation classes along select Rainbow River transects ......................................................................................... 4-19 4.4-1 Median elevation (ft-NGVD) of vegetation classes and wetted perimeter breakpoint along the Rainbow River transects ....................................................... 4-27 iii Table of Contents (continued) Tables Page 4.4-2 Critical stage and discharge values for detrital transfer.......................................... 4-29 4.4-3 Frequency and duration parameters for WRV-4 under baseline and MFL scenarios........................................................................................................ 4-29 4.7-1 Median elevation (NGVD) of vegetation classes and wetted perimeter breakpoint along the Rainbow River transects ....................................................... 4-41 4.7-2 Critical stage and discharge values for nutrient filtration....................................... 4-42 4.7.3 Frequency and duration parameters for WRV-7 under baseline and MFL scenarios........................................................................................................ 4-42 4.8-1 Critical stage and discharge values for sediment load............................................ 4-48 4.8-2 Frequency and duration parameters for WRV-8 under baseline and MFL scenarios........................................................................................................ 4-48 Appendices A - Rainbow River Frequency Analysis Figures Figure A-1 Low Frequency Continuously Not Exceeded – 1-Day Duration Figure A-2 Low Frequency Continuously Not Exceeded – 7-Day Duration Figure A-3 Low Frequency Continuously Not Exceeded – 14-Day Duration Figure A-4 Low Frequency Continuously Not Exceeded – 30-Day Duration Figure A-5 Low Frequency Continuously Not Exceeded – 60-Day Duration Figure A-6 High Frequency