Crooked Creek Watershed TMDL Implementation Plan DRAFT REPORT February 2008 Submitted to: Illinois Environmental Protection Agency 1021 N. Grand Avenue East Springfield, IL 62702 Submitted by: Tetra Tech Illinois Environmental Protection Agency Crooked Creek Watershed TMDL Implementation Plan Table of Contents Key Findings.................................................................................................................................................vii 1.0 Introduction ...................................................................................................................................... 1 2.0 Description of Waterbody and Watershed Characteristics ........................................................ 5 3.0 Water Quality Data, Impairments, and TMDL Allocations..................................................... 11 3.1 Total Phosphorus ......................................................................................................................... 11 3.1.1 Water Quality Standards .........................................................................................................11 3.1.2 Impairments in the Crooked Creek Watershed....................................................................... 11 3.1.3 TMDL Allocations .................................................................................................................. 12 3.2 Dissolved Oxygen........................................................................................................................ 13 3.3 Manganese.................................................................................................................................... 13 3.3.1 Water Quality Standards .........................................................................................................13 3.3.2 Impairments in the Crooked Creek Watershed....................................................................... 13 3.3.3 TMDL Allocations .................................................................................................................. 15 3.4 Atrazine ........................................................................................................................................ 16 3.4.1 Water Quality Standards .........................................................................................................16 3.4.2 Impairments in the Crooked Creek Watershed....................................................................... 16 3.4.3 TMDL Allocations .................................................................................................................. 16 3.5 pH ................................................................................................................................................. 17 3.5.1 Water Quality Standards .........................................................................................................17 3.5.2 Impairments in the Crooked Creek Watershed....................................................................... 17 3.5.3 TMDL Allocations .................................................................................................................. 17 4.0 Pollutant Sources In the Crooked Creek Watershed................................................................. 19 4.1 Point Source Dischargers............................................................................................................. 19 4.1.1 Phosphorus............................................................................................................................... 24 4.2 Onsite Wastewater Treatment Systems....................................................................................... 24 4.2.1 Phosphorus............................................................................................................................... 24 4.3 Crop Production........................................................................................................................... 25 4.3.1 Phosphorus............................................................................................................................... 25 4.3.2 Manganese ............................................................................................................................... 26 4.3.3 Atrazine.................................................................................................................................... 26 4.4 Animal Operations....................................................................................................................... 26 4.4.1 Phosphorus............................................................................................................................... 27 4.5 Streambank and Lake Shore Erosion .......................................................................................... 29 4.6 Internal Loading from Lake Bottom Sediments ........................................................................ 29 4.6.1 Phosphorus............................................................................................................................... 31 4.6.2 Manganese ............................................................................................................................... 32 4.7 Domestic Pets and Wildlife Populations..................................................................................... 32 5.0 Best Management Practices .......................................................................................................... 33 5.1 Proper Maintenance of Onsite Systems ...................................................................................... 33 5.1.1 Effectiveness............................................................................................................................ 34 5.1.2 Costs......................................................................................................................................... 34 5.2 Nutrient Management Plans ........................................................................................................ 35 5.2.1 Effectiveness............................................................................................................................ 38 5.2.2 Costs......................................................................................................................................... 38 5.3 Conservation Tillage.................................................................................................................... 39 5.3.1 Effectiveness............................................................................................................................ 41 5.3.2 Costs......................................................................................................................................... 42 5.4 Cover Crops ................................................................................................................................. 42 5.4.1 Effectiveness............................................................................................................................ 44 5.4.2 Costs......................................................................................................................................... 44 Draft i Illinois Environmental Protection Agency Crooked Creek Watershed TMDL Implementation Plan 5.5 Filter Strips................................................................................................................................... 44 5.5.1 Effectiveness............................................................................................................................ 45 5.5.2 Costs......................................................................................................................................... 46 5.6 Grassed Waterways...................................................................................................................... 47 5.6.1 Effectiveness............................................................................................................................ 48 5.6.2 Costs......................................................................................................................................... 48 5.7 Riparian Buffers........................................................................................................................... 49 5.7.1 Effectiveness............................................................................................................................ 50 5.7.2 Costs......................................................................................................................................... 51 5.8 Constructed Wetlands.................................................................................................................. 52 5.8.1 Effectiveness............................................................................................................................ 53 5.8.2 Costs......................................................................................................................................... 53 5.9 Controlled Drainage..................................................................................................................... 53 5.9.1 Effectiveness............................................................................................................................ 55 5.9.2 Costs........................................................................................................................................