1. Potential Climate Change Impacts to the NW Hydroelectric System NW Hydroelectric Association Conference February 20, 2013

2. Outline Global Circulation Model Output Assessing impacts to the hydroelectric system Mitigation Actions? February 20, 2013 2

3. Global Climate Models Climate Impacts Group – University of Washington Up to 20 climate models At least 2 GHG scenarios Downscaled for the NW Two key outputs for our analysis: Temperature changes Altered natural river flows Can also model climate studies from other groups if data is available February 20, 2013 3

4. River Management Joint Operating Committee (RMJOC) Two key functions: 1.Vet natural flow and temperature data 2.Provide additional data required to run hydro studies Flood control elevations Hydro operating rule curves

5. Precipitation Changes (~2030) 5 Source: Climate and Hydrology Datasets for Use in the RMJOC Agencies’ Longer-Term Planning Studies: Part I - Future Climate and Hydrology Datasets No significant overall change

6. Temperature Changes (~2030) 6 Source: Climate and Hydrology Datasets for Use in the RMJOC Agencies’ Longer-Term Planning Studies: Part I - Future Climate and Hydrology Datasets Expected higher temperatures

7. February 20, 2013 7 Source: Climate and Hydrology Datasets for Use in the RMJOC Agencies’ Longer-Term Planning Studies: Part I - Future Climate and Hydrology Datasets Precipitation can be higher or lower Temperature is always higher Temp and Precipitation Changes

8. 8 Source: Climate and Hydrology Datasets for Use in the RMJOC Agencies’ Longer-Term Planning Studies: Part I - Future Climate and Hydrology Datasets Change in Natural Flows @ The Dalles (~2030)

9. February 20, 2013 9

10. CIG Forecast Changes Runoff volume and river flow Volume not likely to change significantly Higher winter flows, lower summer flows Temperature More likely to increase than decrease Median case 2.05 degrees 0 F higher by 2030 February 20, 2013 10

11. Outline Global Circulation Model Output Assessing impacts to the hydroelectric system Dealing with climate uncertainty February 20, 2013 11

12. Temperature Effects on Demand ~2030 (For illustration only)

13. Changes to Regulated Outflow ~2030 (For illustration only) February 20, 2013 13

14. Changes to Power Generation ~2030 (For illustration only) February 20, 2013 14

15. Impacts to Power Generation ~2030 (For illustration only) Changes to:FebruaryJuly Generation+ 1,700 MW- 1,000 MW Demand- 1,000 MW+ 3,000 MW Balance + + 2,700 MW - - 4,000 MW

16. Outline Global Circulation Model Output Assessing impacts to the hydroelectric system Mitigation Actions? February 20, 2013 16

17. Typical Reservoir Operations

18. Potential Mitigating Actions (My opinion only – not endorsed by the Council) 1.Release more water in summer 2.Coordinate with Canada for additional summer releases 3.Refill in winter with anticipated additional rainfall 4.Develop better forecasting methods for fall and winter flows – the beauty of this approach is that hydro operations will be better regardless of whether we see future warming or cooling

19. Potential Mitigating Operations

20. Other Issues to Consider  Climate change adjusted streamflows come from one source only  Issue of frequency of extreme events is not well quantified  Current analysis assumes equal likelihood for all streamflows – Should apply weights based on longer records – Apply different weights for climate studies February 20, 2013 20