Modeling Report WBIDs 2893K & 2893I Lake Poinsett – St. Johns River above Puzzle Lake – Upper St. Johns River Basin Nutrients and Dissolved Oxygen May 22, 2013 1 | P a g e Contents Watershed Description .................................................................................................................... 1 TMDL Targets ................................................................................................................................ 5 Nutrients Flowing Streams ......................................................................................................... 5 Narrative Nutrient Criteria ................................................................................................... 6 Florida's adopted numeric nutrient criteria for streams ................................................... 6 Dissolved Oxygen Criteria ......................................................................................................... 7 Natural Conditions ..................................................................................................................... 7 Biochemical Oxygen Demand Criteria ..................................................................................... 8 Modeling Approach ........................................................................................................................ 8 LSPC Watershed Model .............................................................................................................. 8 WASP Water Quality Model....................................................................................................... 8 LSPC Application to Lake Poinsett and St. Johns River above Puzzle Lake Watershed ....... 9 Watershed Delineation and Landuse ....................................................................................... 9 Meteorological Information ...................................................................................................... 11 Hydraulic Calibration ............................................................................................................ 12 Water Quality Model Application ............................................................................................. 13 Model Network ...................................................................................................................... 13 Water Quality Model Calibration .............................................................................................. 14 Water Temperature ................................................................................................................ 15 Dissolved Oxygen.................................................................................................................. 19 Biochemical Oxygen Demand ............................................................................................... 21 Chlorophyll a ......................................................................................................................... 24 Nitrogen ................................................................................................................................. 26 Phosphorus............................................................................................................................. 29 Current Loads ............................................................................................................................ 31 Modeling Scenarios ...................................................................................................................... 31 Natural Condition Analysis ....................................................................................................... 32 ii | P a g e TMDL Load Reductions ........................................................................................................... 33 TMDL Determination ................................................................................................................... 33 Table of Figures Figure 1 Location of St. Johns River above Puzzle Lake Watershed and WBID (2893I) ............. 2 Figure 2 Location of Puzzle Lake (WBID 2893K)) ....................................................................... 3 Figure 3 Landuse Distribution for Upper St. Johns River Basin .................................................... 4 Figure 4 Lake Poinsett and St. Johns River above Puzzle Lake Watershed Delineation ............. 10 Figure 5 Hourly Rainfall Station 083137...................................................................................... 11 Figure 6 Flow Calibration for Lake Poinsett and St. Johns River above Puzzle Lake Watershed at USGS Gage 02232500 .................................................................................................................. 12 Figure 7 Flow Calibration for Lake Poinsett and St. Johns River above Puzzle Lake Watershed at USGS Gage 0223134 .................................................................................................................... 13 Figure 8 WASP Model Segmentation........................................................................................... 14 Figure 9 Water Temperature Calibration Lake Poinsett ............................................................... 16 Figure 10 Water Temperature Calibration Lake Poinsett Outlet .................................................. 17 Figure 11 Water Temperature Calibration Segment 5 .................................................................. 18 Figure 12 Water Temperature Calibration Segment 12 ................................................................ 18 Figure 13 Dissolved Oxygen Calibration Lake Poinsett............................................................... 19 Figure 14 Dissolved Oxygen Calibration Lake Poinsett Outlet.................................................... 20 Figure 15 Dissolved Oxygen Calibration Segment 5 ................................................................... 20 Figure 16 Dissolved Oxygen Calibration Segment 12 ................................................................. 21 Figure 17 BOD Calibration Lake Poinsett .................................................................................... 22 Figure 18 BOD Calibration Lake Poinsett Outlet ......................................................................... 22 Figure 19 BOD Calibration Segment 5 ......................................................................................... 23 Figure 20 BOD Calibration Segment 12 ....................................................................................... 23 Figure 21 Chlorophyll a Calibration Lake Poinsett ...................................................................... 24 Figure 22 Chlorophyll a Calibration Lake Poinsett Outlet ........................................................... 25 Figure 23 Chlorophyll a Calibration Segment 5 ........................................................................... 25 iii | P a g e Figure 24 Chlorophyll a Calibration Segment 12 ......................................................................... 26 Figure 25 Total Nitrogen Calibration Lake Poinsett..................................................................... 27 Figure 26 Total Nitrogen Calibration Lake Poinsett Outlet.......................................................... 27 Figure 27 Total Nitrogen Calibration Segment 5 ......................................................................... 28 Figure 28 Total Nitrogen Calibration Segment 12 ....................................................................... 28 Figure 29 Total Phosphorus Calibration Lake Poinsett ................................................................ 29 Figure 30 Total Phosphorus Calibration Lake Poinsett Outlet ..................................................... 30 Figure 31 Total Phosphorus Calibration Segment 5 ..................................................................... 30 Figure 32 Total Phosphorus Calibration Segment 12 ................................................................... 31 Figure 33 Dissolved Oxygen Concentration Probability Current vs. Natural Condition ............. 33 Table of Tables Table 1 Inland Numeric Nutrient Criteria ....................................................................................... 6 Table 2 Annual Rainfall for Simulation Period ............................................................................ 11 Table 3 Impaired Waters Rule Database Stations used in Water Quality Model Calibration ...... 15 Table 4 Predicted vs. Observed Annual Average Concentrations ................................................ 15 Table 5 Annual Average Current Loads (1997-2009) ................................................................. 31 Table 6 Natural Condition Annual Average Model Predictions ................................................... 32 Table 7 Annual Average Loadings for Natural Condition ............................................................ 32 Table 8 TMDL Determination ...................................................................................................... 33 iv | P a g e Modeling Report: WBID: 3154 – Lake Poinsett and St. Johns River above Puzzle Lake – Nutrient/Dissolved Oxygen TMDL May 22, 2013 Watershed Description Lake Poinsett lies in southern Brevard County just west of the city of Melbourne. It is an element of the upper St. Johns River, being located about a mile upstream of where US Highway 192 crosses the river. Lake Poinsett and its smaller