Prepared in cooperation with the U.S. Army Corps of Engineers and the Oregon Association of Clean Water Agencies Thermal Effects of Dams in the Willamette River Basin, Oregon Scientific Investigations Report 2010–5153 U.S. Department of the Interior U.S. Geological Survey Cover: Photograph of Detroit Dam on the North Santiam River. Back Cover: Photographs, from left to right, by row: Top row Big Cliff Dam on the North Santiam River Detroit Dam on the North Santiam River Foster Dam on the South Santiam River Green Peter Dam on the Middle Santiam River 2nd row: Blue River Dam on Blue River Cougar Dam on the South Fork McKenzie River Fall Creek Dam on Fall Creek Dexter Dam on the Middle Fork Willamette River 3rd row: Lookout Point Dam on the Middle Fork Willamette River Hills Creek Dam on the Middle Fork Willamette River Dorena Dam on the Row River Cottage Grove Dam on the Coast Fork Willamette River Bottom row: Fern Ridge Dam on the Long Tom River River Mill Dam on the Clackamas River All photographs except that of River Mill Dam are from the U.S. Army Corps of Engineers’ Digital Visual Library at https://eportal.usace.army.mil/sites/DVL/ Photograph of River Mill Dam is from Portland General Electric. All photographs are used here with the permission of the source entities. Thermal Effects of Dams in the Willamette River Basin, Oregon By Stewart A. Rounds Prepared in cooperation with the U.S. Army Corps of Engineers and the Oregon Association of Clean Water Agencies Scientific Investigations Report 2010–5153 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2010 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 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Suggested citation: Rounds, S.A., 2010, Thermal effects of dams in the Willamette River basin, Oregon: U.S. Geological Survey Scientific Investigations Report 2010-5153, 64 p. iii Contents Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................2 Background............................................................................................................................................2 Description of Study Area ...................................................................................................................3 Purpose and Scope ..............................................................................................................................6 Methods and Models ....................................................................................................................................6 Dam-Site Flow Estimation ...................................................................................................................6 Dam-Site Temperature Estimation .....................................................................................................8 Regressions ..................................................................................................................................8 Mass and Energy Balances .....................................................................................................10 Downstream Warming ..............................................................................................................10 Flow and Temperature Models .........................................................................................................11 Data Sources .......................................................................................................................................12 Thermal Effects of Dams in the Willamette River Basin .......................................................................13 Without-Dam Flow Estimates at Dam Sites ....................................................................................13 Without-Dam Temperature Estimates at Dam Sites .....................................................................15 Big Cliff and Detroit Dams ........................................................................................................16 Blue River Dam ...........................................................................................................................20 Cottage Grove Dam ...................................................................................................................23 Cougar Dam ................................................................................................................................24 Dexter and Lookout Point Dams ..............................................................................................26 Dorena Dam ................................................................................................................................28 Fall Creek Dam............................................................................................................................29 Fern Ridge Dam ..........................................................................................................................31 Foster Dam ..................................................................................................................................32 Green Peter Dam .......................................................................................................................33 Hills Creek Dam ..........................................................................................................................35 River Mill Dam ............................................................................................................................36 Downstream Effects of Willamette Basin Dams ...........................................................................37 Downstream Flows ....................................................................................................................37 Downstream Temperatures ......................................................................................................39 Summary and Conclusions .........................................................................................................................43 Acknowledgments .......................................................................................................................................44 References Cited..........................................................................................................................................45 Appendixes ...................................................................................................................................................47 Appendix A. Graphs of Without-Dam Flow Estimates at Willamette River Basin Dam Sites .......................................................................................................................................48 Appendix B. Time/Distance Color Maps Showing the Downstream Thermal Effects of Willamette River Basin Dams ...........................................................................................................................52 Appendix C. Graphs of Modeled Temperature Distributions Downstream of Willamette River Basin Dam Sites..............................................................................................................................56 iv Figures Figure 1. Map of the Willamette River basin, Oregon ……………………………………… 4 Figure 2. Map of major physiographic regions in the Willamette River basin, Oregon ……… 5 Figure 3. Diagram showing imposed seasonal variation in the estimated correction for evaporative losses from Willamette River basin reservoirs, Oregon ……………… 7 Figure 4. Flow chart showing process for estimating without-dam water temperatures at dam sites in the Willamette River basin, Oregon ……………………………… 9 Figure 5. Graph showing measured and estimated streamflow for conditions with and without upstream dams in the Middle Fork Willamette River at Dexter Dam, just downstream of Lookout Point Dam in the Willamette River basin, Oregon, 2001–02 …………………………………………………………………………… 13 Figure 6. Graphs showing measured and estimated water temperatures for conditions with and without upstream dams at the Big Cliff / Detroit, Blue River, and Cottage Grove dam sites in the Willamette River basin, Oregon, 2001–02 ………… 17 Figure 7. Graphs showing cumulative frequency curves of measured and estimated water temperatures for conditions with and without upstream dams at the Big Cliff dam site in the Williamette River basin, Oregon, 2001–02 ……………… 18 Figure 8. Graphs showing correlation of water temperatures for Blue River (BR) and Blowout Creek (BC) in the Willamette