Little Wabash River I Watershed TMDL Implementation Plan PUBLIC REVIEW DRAFT REPORT April 14, 2008 Submitted to: Illinois Environmental Protection Agency 1021 N. Grand Avenue East Springfield, IL 62702 Submitted by: Tetra Tech Illinois Environmental Protection Agency Little Wabash River I Watershed TMDL Implementation Plan TABLE OF CONTENTS List of Tables ..............................................................................................................................................iv List of Figures..............................................................................................................................................v 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 Little Wabash River I Watershed...........................................................11 3.1.3 TMDL Allocations................................................................................................................12 3.2 Dissolved Oxygen .....................................................................................................................15 3.2.1 Water Quality Standards .......................................................................................................15 3.2.2 Impairments in the Little Wabash River I Watershed...........................................................15 3.2.3 TMDL Allocations................................................................................................................15 3.3 pH ..............................................................................................................................................17 3.3.1 Water Quality Standards .......................................................................................................17 3.3.2 Impairments in the Little Wabash River I Watershed...........................................................17 3.3.3 TMDL Allocations................................................................................................................17 3.4 Manganese.................................................................................................................................19 3.4.1 Water Quality Standards .......................................................................................................19 3.4.2 Impairments in the Little Wabash River I Watershed...........................................................19 3.4.3 TMDL Allocations................................................................................................................21 3.5 Atrazine .....................................................................................................................................21 3.5.1 Water Quality Standards .......................................................................................................21 3.5.2 Impairments in the Little Wabash River I Watershed...........................................................22 3.5.3 TMDL Allocations................................................................................................................22 3.6 Fecal Coliform...........................................................................................................................22 3.6.1 Water Quality Standards .......................................................................................................24 3.6.2 Impairments in the Little Wabash River I Watershed...........................................................24 3.6.3 TMDL Allocations................................................................................................................24 4.0 Pollutant Sources In the Little Wabash River I Watershed ....................................................27 4.1 Point Source Dischargers...........................................................................................................27 4.1.1 Phosphorus ............................................................................................................................28 4.1.2 Dissolved Oxygen .................................................................................................................28 4.1.3 Fecal Coliform ......................................................................................................................29 4.2 Onsite Wastewater Treatment Systems .....................................................................................29 4.2.1 Phosphorus ............................................................................................................................29 4.2.2 Dissolved Oxygen .................................................................................................................31 4.2.3 Fecal Coliform ......................................................................................................................32 4.3 Crop Production.........................................................................................................................33 4.3.1 Phosphorus ............................................................................................................................33 4.3.2 Dissolved Oxygen .................................................................................................................33 4.3.3 Manganese.............................................................................................................................33 4.3.4 Atrazine.................................................................................................................................33 4.4 Animal Operations.....................................................................................................................34 4.4.1 Phosphorus ............................................................................................................................35 4.4.2 Dissolved Oxygen .................................................................................................................36 4.4.3 Fecal Coliform ......................................................................................................................37 4.5 Streambank and Lake Shore Erosion.........................................................................................37 Public Review Draft i Illinois Environmental Protection Agency Little Wabash River I Watershed TMDL Implementation Plan 4.6 Internal Loading from Lake and River Bottom Sediments........................................................38 4.6.1 Phosphorus ............................................................................................................................40 4.6.2 Manganese.............................................................................................................................40 4.7 Historic and Active Oil Mining Operations...............................................................................41 4.8 Domestic Pets and Wildlife Populations ...................................................................................41 5.0 Best Management Practices ........................................................................................................43 5.1 Disinfection of Primary Effluent from Sewage Treatment Plants.............................................43 5.1.1 Effectiveness .........................................................................................................................45 5.1.2 Costs......................................................................................................................................45 5.2 Control of Combined Sewer Overflows (CSOs) .......................................................................46 5.2.1 Effectiveness .........................................................................................................................49 5.2.2 Costs......................................................................................................................................49 5.3 Proper Maintenance of Onsite Systems.....................................................................................49 5.3.1 Effectiveness .........................................................................................................................51 5.3.2 Costs......................................................................................................................................51 5.4 Nutrient Management Plans ......................................................................................................52 5.4.1 Effectiveness .........................................................................................................................55 5.4.2 Costs......................................................................................................................................55