STAGE 1 REPORT Rend Lake Watershed TMDL Final Stage 1 Report Prepared for Illinois EPA June 2014 Table of Contents Section 1 Goals and Objectives for the Rend Lake Watershed 1.1 Total Maximum Daily Load Overview ..................................................................................................... 1-1 1.2 TMDL Goals and Objectives for the Rend Lake Watershed ............................................................ 1-2 1.3 Report Overview .............................................................................................................................................. 1-4 Section 2 Rend Lake Watershed Description 2.1 Rend Lake Watershed Location ................................................................................................................. 2-1 2.2 Topography ........................................................................................................................................................ 2-1 2.3 Land Use ............................................................................................................................................................... 2-1 2.3.1 Subbasin Land Use ....................................................................................................................... 2-2 2.4 Soils ........................................................................................................................................................................ 2-6 2.4.1 Rend Lake Watershed Soil Characteristics ....................................................................... 2-6 2.5 Population ........................................................................................................................................................... 2-7 2.6 Climate, Pan Evaporation, and Streamflow .......................................................................................... 2-8 2.6.1 Climate .............................................................................................................................................. 2-8 2.6.2 Pan Evaporation............................................................................................................................ 2-8 2.6.3 Streamflow ...................................................................................................................................... 2-9 Section 3 Rend Lake Watershed Public Participation 3.1 Rend Lake Watershed Public Participation and Involvement ...................................................... 3-1 Section 4 Rend Lake 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 ............................................................................................................... 4-2 4.4 Potential Pollutant Sources.......................................................................................................................... 4-3 Section 5 Rend Lake Watershed Characterization 5.1 Water Quality Data .......................................................................................................................................... 5-1 5.1.1 Stream Water Quality Data ...................................................................................................... 5-2 5.1.1.1 Dissolved Oxygen ..................................................................................................... 5-2 5.1.1.2 Fecal Coliform ............................................................................................................ 5-3 5.1.1.3 pH .................................................................................................................................... 5-3 5.1.1.4 Metals ............................................................................................................................ 5-4 5.1.2 Lake Water Quality Data ........................................................................................................... 5-5 5.1.2.1 Rend Lake .................................................................................................................... 5-5 5.1.2.1.1 Total Phosphorus in Rend Lake ................................................ 5-6 5.1.2.1.2 Manganese in Rend Lake .............................................................. 5-7 5.1.2.2 Benton Reservoir ...................................................................................................... 5-8 5.1.2.2.1 Total Phosphorus in Benton Reservoir .................................. 5-9 5.1.2.3 Ashley Reservoir .................................................................................................... 5-10 5.1.2.3.1 Total Phosphorus in Ashley Reservoir ................................ 5-11 i Contents 5.1.2.3.2 Dissolved Oxygen in Ashley Reservoir ................................ 5-12 5.1.2.4 Lake Jaycee ............................................................................................................... 5-12 5.1.2.4.1 Total Phosphorus in Lake Jaycee ........................................... 5-13 5.2 Reservoir Characteristics ........................................................................................................................... 5-14 5.2.1 Rend Lake ...................................................................................................................................... 5-14 5.2.2 Benton Reservoir ....................................................................................................................... 5-15 5.2.3 Ashley Reservoir ........................................................................................................................ 5-15 5.2.4 Lake Jaycee ................................................................................................................................... 5-15 5.3 Point Sources ................................................................................................................................................... 5-16 5.4 Nonpoint Sources .......................................................................................................................................... 5-17 5.4.1 Crop Information ....................................................................................................................... 5-17 5.4.2 Animal Operations .................................................................................................................... 5-18 5.4.3 Septic Systems ............................................................................................................................. 5-19 5.5 Watershed Studies and Other Watershed Information ................................................................ 5-19 Section 6 Approach to Developing TMDL and Identification of Data Needs 6.1 Simple and Detailed Approaches for Developing TMDLs .............................................................. 6-1 6.2 Additional Data Needs for TMDL Development in the Rend Lake Watershed ..................... 6-2 6.3 Approaches for Developing TMDLs for Stream Segments in Rend Lake Watershed ......... 6-3 6.3.1 Recommended Approach for Metals and Fecal Coliform TMDLs for Stream Segments ............................................................................................................. 6-3 6.3.2 Recommended Approach for pH TMDL in Big Muddy River Segment N-08 .................................................................................................................... 6-4 6.3.3 Recommended Approach for DO TMDLs in Impaired Stream Segments ............................................................................................................................. 6-4 6.4 Approaches for Developing TMDLs for Lake Segments in the Rend Lake Watershed ...... 6-4 6.4.1 Recommended Approach for Total Phosphorus and DO TMDLs ................ 6-4 6.4.2 Recommended Approach for the Manganese TMDL in Rend Lake ............ 6-5 Appendices Appendix A – Land Use Categories Appendix B – Soil Characteristics Appendix C – Water Quality Data ii Contents List of Tables 1-1 Impaired Water Bodies in Rend Lake Watershed .............................................................................. 1-2 2-1 Land Cover and Land Use in Rend Lake Watershed ......................................................................... 2-2 2-2 Land Cover and Land Use in the Ashley Reservoir Subbasin ........................................................ 2-2 2-3 Land Cover and Land Use in the Lake Benton Subbasin ................................................................. 2-3 2-4 Land Cover and Land Use in the Lake Jaycees Subbasin ................................................................. 2-3 2-5 Land Cover and Land Use in the Snow Creek Subbasin................................................................... 2-4 2-6 Land Cover and Land Use in the Gun Creek Subbasin ...................................................................... 2-4 2-7 Land