Implications of Climate Change for the Columbia River Basin

1. Implications of Climate Change for the Columbia River Basin • Alan F. Hamlet, • Philip W. Mote, • Dennis P. Lettenmaier • JISAO/CSES Climate Impacts Group • Dept. of Civil and Environmental Engineering • University of Washington

2. Overview of the Columbia’s Development

3. A Columbia River Development Timeline Dworshak and Mica Dams completed 1973 Hungry Horse Dam completed 1953 Albeni Falls Dam completed 1955 Bonneville Dam completed 1938 Keenleyside Dam completed 1968 Snake River Sockeye and Chinook and Kootenai River Sturgeon listed under ESA 1991-1994 Duncan Dam completed 1967 Eight additional ESA listings for Sockeye, Chum, Chinook and Steelhead throughout the PNW 1999 Libby Dam completed 1976 PNW Power Planning and Conservation Act 1980 Columbia River Treaty Ratified 1964 Grand Coulee Dam completed 1941 NMFS Biological Opinion 1995

5. Changes in the Columbia’s Flow Regime Associated with Consumptive Use and Reservoir Regulation

6. Changes in Regulated Peak Flow at The Dalles Completion of Major Dams

7. Climate Change Scenarios

8. +3.2°C °C +1.7°C +0.7°C 1.2-5.5°C 0.9-2.4°C 0.4-1.0°C Observed 20th century variability Pacific Northwest

9. % +6% +2% +1% Observed 20th century variability -1 to +3% -1 to +9% -2 to +21% Pacific Northwest

10. Will Global Warming be “Warm and Wet” or “Warm and Dry”? Answer: Probably BOTH!

11. Hydrologic Changes Associated with Warming

12. The warmest locations that accumulate snowpack are most sensitive to warming +2.3C, +6.8% winter precip

13. Naturalized Flow for Historic and Global Warming Scenarios Compared to Effects of Regulation at 1990 Level Development Historic Naturalized Flow Estimated Range of Naturalized Flow With 2060’s Warming Regulated Flow

14. Changes in Simulated April 1 Snowpack for the Canadian and U.S. portions of the Columbia River basin (% change relative to current climate) 20th Century Climate “2040s” (+1.7 C) “2060s” (+ 2.25 C) -3.6% -11.5% -21.4% -34.8% April 1 SWE (mm)

15. Effects of Basin Winter Temperatures on Streamflow Timing Shifts Northern Location (colder winter temperatures) Southern Location (warmer winter temperatures)

16. Recession of the Muir Glacier Aug, 13, 1941 Aug, 31, 2004 Image Credit: National Snow and Ice Data Center, W. O. Field, B. F. Molnia http://nsidc.org/data/glacier_photo/special_high_res.html

17. Wide-Spread Glacial Retreat has Accompanied 20th Century Warming. Loss of glacial mass may increase summer flow in the short term and decrease summer flow in the long term. 1902 2002 The recession of the Illecillewaet Glacier at Rogers Pass between 1902 and 2002. Photographs courtesy of the Whyte Museum of the Canadian Rockies & Dr. Henry Vaux.

18. Hydropower Impacts

19. Impacts on Columbia Basin hydropower supplies • Winter and Spring: increased generation • Summer: decreased generation • Annual: total production will depend primarily on annual precipitation (+2C, +6%) (+2.3C, +5%) (+2.9C, -4%) NWPCC (2005)

20. Temperature Effects on Demand

21. Climate change adaptation may involve complex tradeoffs between competing system objectives Source: Payne, J.T., A.W. Wood, A.F. Hamlet, R.N. Palmer and D.P. Lettenmaier, 2004, Mitigating the effects of climate change on the water resources of the Columbia River basin, Climatic Change Vol. 62, Issue 1-3, 233-256

22. Flood Control vs Reservoir Refill

23. Flood Control vs. Refill : Current Climate Full

24. Flood Control vs. Refill : Current Climate : + 2.25 oC No adaption Streamflow timing shifts can reduce the reliability of reservoir refill + 2.25 oC Full

25. Flood Control vs. Refill : Current Climate : + 2.25 oC No adaption : + 2.25 oC plus adaption Streamflow timing shifts can reduce the reliability of reservoir refill + 2.25 oC Full

26. Instream Flow Augmentation and Water Quality

27. Streamflow Timing Shifts Will Tend to Reduce Late Summer Low Flows

28. CDF Plots of Simulated Regulated Flow to the Hanford Reach in August August

29. Temperature thresholds for coldwater fish in freshwater • Warming temperatures will increasingly stress coldwater fish in the warmest parts of our region • A monthly average air temperature of 68ºF (20ºC) has been used as an upper limit for resident cold water fish habitat, and is known to stress Pacific salmon during periods of freshwater migration, spawning, and rearing +1.7 °C +2.3 °C

30. Implications for Transboundary Water Management in the Columbia Basin • Climate change will result in significant hydrologic changes in the Columbia River and its tributaries. • Snowpack in the BC portion of the Columbia basin is much less sensitive to warming in comparison with portions of the basin in the U.S. and streamflow timing shifts will also be smaller in Canada. • As warming progresses, Canada will have an increasing fraction of the snowpack contributing to summer streamflow volumes in the Columbia basin. • These differing impacts in the two countries have the potential to “unbalance” the current coordination agreements, and will present serious challenges to meeting instream flows on the U.S. side. • Changes in flood control, hydropower production, and instream flow augmentation will all be needed as the flow regime changes.

31. Some Thoughts on Climate Change Adaptation • in the Columbia Basin • In 1975 the Columbia basin’s operating system was state of the art. 30 years later, the basin’s operating plan is both out of date and struggling to keep pace with the many changes in the basin. • Do the current water resources policies and transboundary agreements in the Columbia basin have the scope and flexibility needed to cope with a changing basin, a rapidly evolving climate system, and increasing human populations? If not, how can we effectively reduce the Columbia’s vulnerability to these changes? • Are changes in the margins of the Columbia’s current reservoir operating policies going to be sufficient?