Willamette Basin Annual Water Quality Report for 2015 Detroit Reservoir at Low Elevation (1202 feet) on November 6, due to 2015 Drought, North Santiam River, Oregon Final Report Page intentionally left blank Final Report, July 2016 i Table Of Contents 1.0 Executive Summary ................................................................................................................ 10 2.0 Introduction and Purpose ........................................................................................................ 12 3.0 Water Quality related Achievements ...................................................................................... 14 3.1 Corps Achievements in Meeting CWA-TMDL and EPA-BiOp Recommendations: ............. 14 4.0 Willamette Project Background .............................................................................................. 15 5.0 Description of the 2015 Water Year ....................................................................................... 19 5.1 Willamette Basin Hydrology .................................................................................................. 19 5.2 Willamette Mainstem Conditions ........................................................................................... 21 6.0 North Santiam Subbasin.......................................................................................................... 25 6.1 Water Quality Improvement Measures Conducted in 2015 .................................................... 25 6.2 Water Quality Monitoring and Results ................................................................................... 26 6.2.1 Water Quality Monitoring .............................................................................................. 26 6.2.2 Water Temperature Results ............................................................................................ 27 6.2.3 Total Dissolved Gas Saturation Results ......................................................................... 32 6.3 Biological Monitoring and Results ......................................................................................... 34 7.0 South Santiam Subbasin.......................................................................................................... 37 7.1 Water Quality Improvement Measures Conducted in 2015 .................................................... 37 7.2 Water Quality Monitoring And Results .................................................................................. 37 7.2.1 Water Quality Monitoring .............................................................................................. 37 7.2.2 Water Temperature Results ............................................................................................ 38 7.2.3 Total Dissolved Gas Saturation Results ......................................................................... 47 7.3 Biological Monitoring And Results ........................................................................................ 48 8.0 McKenzie Subbasin ................................................................................................................ 50 8.1 Water Quality Improvement Measures Conducted in 2015 .................................................... 50 8.2 Water Quality Monitoring and Results ................................................................................... 52 8.2.1 Water Quality Monitoring .............................................................................................. 52 8.2.2 Water Temperature Results ............................................................................................ 53 8.2.3 Total Dissolved Gas Saturation Results ......................................................................... 60 8.3 Biological Monitoring And Results ........................................................................................ 61 9.0 Middle Fork Willamette Subbasin .......................................................................................... 63 9.1 Water Quality Improvement Measures Conducted in 2015 .................................................... 63 9.2 Water Quality Monitoring and Results ................................................................................... 64 9.2.1 Water Quality Monitoring .............................................................................................. 64 9.2.2 Water Temperature Results ............................................................................................ 66 9.2.3 Total Dissolved Gas Saturation Results ......................................................................... 82 9.3 Biological Monitoring and Results ......................................................................................... 83 10.0 Coast Fork Willamette and Long Tom Subbasins .................................................................. 86 10.1 Water Quality Improvement Measures Conducted in 2015 ............................................... 86 10.2 Water Quality Monitoring and Results ............................................................................... 86 10.2.1 Water Quality Monitoring .......................................................................................... 86 10.2.2 Water Temperature Results ........................................................................................ 87 11.0 Willamette Basin annual interim TMDL water quality Plan .................................................. 92 11.1 Introduction and Purpose .................................................................................................... 92 11.2 TMDL Targets Compared to Downstream Temperatures .................................................. 93 11.2.1 North Santiam Subbasin – Detroit / Big Cliff Reservoirs .......................................... 93 11.2.2 South Santiam Subbasin – Green Peter / Foster Reservoirs ...................................... 95 11.2.3 McKenzie Subbasin – Cougar / Blue River Reservoirs ............................................. 98 11.2.4 Middle Fork Willamette Subbasin – Hills Creek / Lookout Point / Dexter / Fall Creek Reservoirs 101 Final Report, July 2016 i 11.2.5 Coast Fork Willamette and Long Tom Subbasins – Cottage Grove / Dorena / Fern Ridge Reservoirs ........................................................................................................................ 106 11.3 Water Quality Considerations - Present and Future ......................................................... 109 12.0 Conclusions ........................................................................................................................... 109 12.1 Water Quality Considerations........................................................................................... 109 12.2 Recommendations and Future Goals ................................................................................ 111 12.2.1 North Santiam Subbasin .......................................................................................... 112 12.2.2 South Santiam Subbasin .......................................................................................... 113 12.2.3 McKenzie Subbasin ................................................................................................. 113 12.2.4 Middle Fork Willamette Subbasin ........................................................................... 113 13.0 Literature Cited ..................................................................................................................... 115 14.0 Appendix A ........................................................................................................................... 119 14.1 Corps Funded USGS Gaging Program and Sites.............................................................. 119 15.0 Appendix B ........................................................................................................................... 124 15.1 Project Descriptions and Drawings .................................................................................. 124 15.1.1 North Santiam Subbasin .......................................................................................... 124 15.1.2 Detroit and Big Cliff Project Description ................................................................ 124 15.1.3 South Santiam Subbasin .......................................................................................... 127 15.1.4 Green Peter and Foster Project Descriptions ........................................................... 128 15.1.5 McKenzie Subbasin ................................................................................................. 131 15.1.6 Cougar ...................................................................................................................... 132 15.1.7 Blue River ................................................................................................................ 134 15.1.8 Middle Fork Willamette Subbasin ........................................................................... 135 15.1.9 Hills Creek ............................................................................................................... 136 15.1.10 Lookout Point and Dexter ........................................................................................ 139 15.1.11 Fall Creek ................................................................................................................. 141 15.1.12 Coast Fork Willamette and Long Tom Subbasins 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