Illinois Bureau of Water Environmental P.O. Box 19276 Protection Agency Springfield, IL 62794-9276 December 2007 IEPA/BOW/07-027 SOUTH FORK SANGAMON RIVER/LAKE TAYLORVILLE WATERSHED TMDL REPORT Printed on Recycled Paper THIS PAGE INTENTIONALLY LEFT BLANK THIS PAGE INTENTIONALLY LEFT BLANK Contents Section 1 Goals and Objectives for South Fork Sangamon River/Lake Taylorville Watershed (0713000702) 1.1 Total Maximum Daily Load (TMDL) Overview............................................. 1-1 1.2 TMDL Goals and Objectives for South Fork Sangamon River/Lake Taylorville Watershed ..................................................................................... 1-2 1.3 Report Overview.............................................................................................. 1-3 Section 2 South Fork Sangamon River/Lake Taylorville Watershed Description 2.1 South Fork Sangamon River/Lake Taylorville Watershed Location............... 2-1 2.2 Topography...................................................................................................... 2-1 2.3 Land Use.......................................................................................................... 2-1 2.4 Soils.................................................................................................................. 2-2 2.4.1 South Fork Sangamon River/Lake Taylorville Watershed Soil Characteristics.................................................................................... 2-3 2.5 Population ........................................................................................................ 2-4 2.6 Climate and Streamflow .................................................................................. 2-4 2.6.1 Climate............................................................................................... 2-4 2.6.2 Streamflow......................................................................................... 2-5 Section 3 Public Participation and Involvement 3.1 South Fork Sangamon River/Lake Taylorville Watershed Public Participation and Involvement......................................................................... 3-1 Section 4 South Fork Sangamon River/Lake Taylorville Watershed Water Quality Standards 4.1 Illinois Water Quality Standards...................................................................... 4-1 4.2 Designated Uses............................................................................................... 4-1 4.2.1 General Use........................................................................................ 4-1 4.2.2 Public and Food Processing Water Supplies ..................................... 4-1 4.3 Illinois Water Quality Standards...................................................................... 4-1 4.4 Potential Pollutant Sources .............................................................................. 4-3 Section 5 South Fork Sangamon River/Lake Taylorville Watershed Characterization 5.1 Water Quality Data .......................................................................................... 5-1 5.1.1 Stream Water Quality Data................................................................ 5-1 5.1.2 Lake and Reservoir Water Quality Data............................................ 5-2 5.1.2.1 Lake Taylorville............................................................... 5-2 5.1.2.1.1 Total Phosphorus.......................................... 5-3 5.1.2.1.2 Manganese .................................................... 5-4 5.1.2.1.3 Dissolved Oxygen......................................... 5-4 i FINAL REPORT Table of Contents Development of Total Maximum Daily Loads South Fork Sangamon River/Lake Taylorville Watershed 5.2 Reservoir Characteristics ................................................................................. 5-4 5.2.1 Lake Taylorville................................................................................. 5-5 5.3 Point Sources................................................................................................... 5-5 5.3.1 Municipal and Industrial Point Sources............................................. 5-5 5.3.1.1 South Fork Sangamon River Segment EO13................... 5-6 5.3.1.2 Other ................................................................................ 5-6 5.3.2 Mining Discharges............................................................................. 5-6 5.4 Nonpoint Sources............................................................................................. 5-6 5.4.1 Crop Information............................................................................... 5-7 5.4.2 Animal Operations............................................................................. 5-7 5.4.3 Septic Systems ................................................................................... 5-8 5.5 Watershed Studies and Other Watershed Information..................................... 5-9 Section 6 Approach to Developing TMDL and Identification of Data Needs 6.1 Simple and Detailed Approaches for Developing TMDLs.............................. 6-1 6.2 Approaches for Developing TMDLs for Stream Segments in the South Fork Sangamon/Lake Taylorville Watershed .................................................. 6-1 6.2.1 Recommended Approach for DO TMDLs for Stream Segments without Major Point Sources ............................................................. 6-1 6.2.2 Recommended Approach for Manganese and Boron TMDLs .......... 6-2 6.3 Approaches for Developing TMDLs for Lake Taylorville.............................. 6-2 6.3.1 Recommended Approach for Total Phosphorus and Dissolved Oxygen TMDLs................................................................................. 6-2 6.3.2 Recommended Approach for Manganese TMDLs............................ 6-3 Section 7 Methodology Development for the South Fork Sangamon River/Lake Taylorville Watershed 7.1 Methodology Overview................................................................................... 7-1 7.1.1 QUAL2K Overview........................................................................... 7-1 7.1.2 Empirical Analysis of Manganese Overview .................................... 7-2 7.1.3 BATHTUB Overview........................................................................ 7-2 7.2 Methodology Development............................................................................. 7-2 7.2.1 QUAL2K Model................................................................................ 7-2 7.2.1.1 QUAL2K Inputs...............................................................7-3 7.2.1.2 QUAL2K Calibration.......................................................7-5 7.2.2 Empirical Analysis of Manganese ..................................................... 7-5 7.3 BATHTUB Model Development and Input .................................................... 7-6 7.3.1 Global Inputs...................................................................................... 7-6 7.3.2 Reservoir Segment Inputs.................................................................. 7-6 7.3.3 Tributary Inputs................................................................................. 7-6 7.4 BATHTUB Confirmatory Analysis................................................................. 7-7 ii FINAL REPORT Table of Contents Development of Total Maximum Daily Loads South Fork Sangamon River/Lake Taylorville Watershed Section 8 Total Maximum Daily Loads for the South Fork Sangamon River/Lake Taylorville Watershed 8.1 TMDL Endpoints............................................................................................. 8-1 8.2 Pollutant Source and Linkage .......................................................................... 8-1 8.3 Allocation......................................................................................................... 8-2 8.3.1 South Fork Sangamon River Manganese TMDL .............................. 8-2 8.3.1.1 Loading Capacity............................................................. 8-2 8.3.1.2 Seasonal Variation........................................................... 8-2 8.3.1.3 Margin of Safety .............................................................. 8-2 8.3.1.4 Waste Load Allocation .................................................... 8-3 8.3.1.5 Load Allocation and TMDL Summary............................ 8-3 8.3.2 South Fork Sangamon River DO TMDL........................................... 8-3 8.3.2.1 Loading Capacity............................................................. 8-3 8.3.3 Total Phosphorus TMDL for Lake Taylorville.................................. 8-4 8.3.3.1 Loading Capacity............................................................. 8-4 8.3.3.2 Seasonal Variation........................................................... 8-4 8.3.3.3 Margin of Safety .............................................................. 8-4 8.3.3.4 Waste Load Allocation .................................................... 8-5 8.3.3.5 Load Allocation and TMDL Summary............................ 8-5 Section 9 Implementation Plan for the South Fork Sangamon River/Lake Lake Taylorville Watershed 9.1 Adaptive Management..................................................................................... 9-1 9.2 Implementation Actions and Management Measures for DO in the South Fork Sangamon River ...................................................................................... 9-2 9.2.1 Point Sources of Oxygen-Demanding Materials ..............................