1. Modeling the Boise Reservoir System with Climate Change Leslie Stillwater, Pacific NW Region

2. Picture Source: CIG (2007) Intergovernmental Panel on Climate Change Scenarios (Year 2040)

3. Approach T and P Adjustments obtained from Climate Impacts Group T and P Adjustments applied to NWS Extended Streamflow Prediction Model to produce daily local inflows (WY1949-1996) Each Climate Scenario was compared to the No Adjustment Scenario to produce daily local gain adjustments Daily local gain adjustments were aggregated into monthly gain adjustments for input to the Snake River revised BA monthly planning model (WY1949-1996) Daily gain adjustments were applied to the Daily Boise Operations Model (WY1949-1996)

11. Comments on the Monthly Planning Studies Assumptions drive the study results –A2 IPCC scenarios (aggressive emissions) –T and P results are scalable to PN Region and to the Boise Basin –Present level diversions –Present level groundwater influences Your point of view influences how you interpret results We addressed uncertainties by employing results from a range of IPCC models

12. Monthly Planning Study Results Probability of Refill is not significantly impacted by the Climate Change scenarios studied Present level Deliveries are not significantly impacted by the Climate Change scenarios studied

13. Daily Operations Studies COE Water Control Manual is followed Each hydrology year (WY1949-1996) starts with Nov 2001 reservoir contents Starting on Jan 1, perfect forecast (Apr – July) -> Apr 1 space requirements (rule curves) Starting on Jan 1, perfect forecast (Jan – Apr) -> release to get to Apr 1 space requirements After Apr 1, go to the rule curves every 2 weeks with perfect forecasts Measure of success is discharge < 7,200 cfs at Glenwood Bridge

14. No Adjustment 1970/1971 Apr 1 Space (AF) required = 950,150 achieved = 885,780

15. Echam T 1970/1971 Apr 1 Space (AF) required = 664,530 achieved = 663,780

16. Giss T 1970/1971 Apr 1 Space (AF) required = 822,790 achieved = 820,390

17. Ipsl T 1970/1971 Apr 1 Space (AF) required = 588,970 achieved = 582,100

18. Echam TP 1970/1971 Apr 1 Space (AF) required = 784,410 achieved = 613,210

19. Giss TP 1970/1971 Apr 1 Space (AF) required = 834,650 achieved = 831,930

20. Ipsl TP 1970/1971 Apr 1 Space (AF) required = 852,310 achieved = 244,280

21. No Adjustment 1970/1971 Apr 1 Space (AF) required = 950,150 achieved = 885,780

22. Comments on the Daily Operations Studies Assumptions drive the study results –A2 IPCC scenarios (aggressive emissions) –T and P results are scalable to PN Region and to the Boise Basin –Historic groundwater influences not removed –Starting storage conditions of Nov 2001 (historic median) –Perfect forecasts We addressed uncertainties by employing results from a range of IPCC models

23. Daily Operations Study Results Reliable forecasts will be even more critical Early forecasts (prior to Jan 1) will be required Drawdown needs to start before Jan 1 Space requirements need to start earlier than Apr 1 Maintaining 55% space in Lucky Peak and Arrowrock may not be possible Glenwood Bridge discharge Jan – Apr will be higher Glenwood Bridge discharge > 7,200 cfs can be anticipated if the wettest scenario is realized