Willamette Basin TMDL: Middle Willamette Subbasin September 2006 CHAPTER 7: MIDDLE WILLAMETTE SUBBASIN Table of Contents WATER QUALITY SUMMARY....................................................................................... 3 Reason for action .........................................................................................................................................................3 Water Quality 303(d) Listed Waterbodies ................................................................................................................4 Water Quality Parameters Addressed.......................................................................................................................4 Water Quality Parameters Not Addressed................................................................................................................5 Who helped us..............................................................................................................................................................5 SUBBASIN OVERVIEW ................................................................................................. 6 Watershed Descriptions ..............................................................................................................................................7 Abernethy Creek Watershed......................................................................................................................................7 Mill Creek Watershed................................................................................................................................................7 Rickreall Creek Watershed........................................................................................................................................8 Willamette River/Chehalem Creek Watershed..........................................................................................................8 MIDDLE WILLAMETTE TEMPERATURE TMDL......................................................... 10 Waterbodies Listed for Temperature ......................................................................................................................11 Pollutant Identification .............................................................................................................................................12 Beneficial Use Identification .....................................................................................................................................13 Salmonid Stream Temperature Requirements .........................................................................................................13 Target Criteria Identification...................................................................................................................................13 Existing Heat Sources................................................................................................................................................16 Nonpoint Sources of Heat........................................................................................................................................16 Point Sources of Heat ..............................................................................................................................................16 Temperature TMDL Approach Summary..............................................................................................................19 Temperature TMDL Analytical Methods Overview ..............................................................................................19 Seasonal Variation.....................................................................................................................................................21 Rickreall Creek Watershed......................................................................................................................................24 Pringle Creek Watershed .........................................................................................................................................26 Patterson Creek........................................................................................................................................................28 Loading Capacity.......................................................................................................................................................29 Critical Condition ....................................................................................................................................................29 Allocations..................................................................................................................................................................29 Wasteload Allocations ...............................................................................................................................................29 Load Allocations ........................................................................................................................................................32 Excess Load................................................................................................................................................................33 Surrogate Measures...................................................................................................................................................33 Margin of Safety ........................................................................................................................................................45 Reserve Capacity .......................................................................................................................................................46 OREGON DEPARTMENT OF ENVIRONMENTAL QUALITY 7-1 Willamette Basin TMDL: Middle Willamette Subbasin September 2006 MIDDLE WILLAMETTE BACTERIA TMDL.................................................................. 47 Waterbodies Listed for Bacteria ..............................................................................................................................48 Pollutant Identification .............................................................................................................................................49 Beneficial Use Identification .....................................................................................................................................49 Target Criteria Identification...................................................................................................................................49 Existing Bacteria Sources..........................................................................................................................................50 Nonpoint Sources of Bacteria..................................................................................................................................50 Point Sources of Bacteria.........................................................................................................................................51 Bacteria TMDL Analytical Methods Overview ......................................................................................................52 Seasonal Variation.....................................................................................................................................................54 Mill Creek Watershed..............................................................................................................................................55 Battle Creek.............................................................................................................................................................60 Load Duration Curves...............................................................................................................................................61 Pringle Creek Watershed .........................................................................................................................................65 Rickreall Creek Watershed-Bashaw Creek..............................................................................................................73 Loading Capacity.......................................................................................................................................................75 Allocations..................................................................................................................................................................76 Wasteload Allocations ...............................................................................................................................................76 Load Allocations ........................................................................................................................................................76 Mill Creek Watershed..............................................................................................................................................77 Pringle Creek Watershed .........................................................................................................................................77 Bashaw Creek Watershed and Rickreall Creek .......................................................................................................78 Middle Willamette Subbasin Percent Reductions....................................................................................................79