1. WESTCAPS Basin Study Planning Meeting Water Resources Planning and Operations Support Group Technical Service Center, Denver, Colorado December 1-2, 2014, Phoenix, AZ

2. Background Public Law 111-11, Subtitle F (SECURE Water Act, SWA, 2009) § 9503. Climate change risks for water and environmental resources in “major Reclamation river basins.” Reclamation’s WaterSMART (Sustain and Manage America’s Resources for Tomorrow) program 1.Basin Studies 2.West-Wide Climate Risk Assessments (WWCRAs) 3.Landscape Conservation Cooperatives (LCCs) SECURE – Science and Engineering to Comprehensively Understand and Responsibly Enhance 8 major Reclamation River Basin

3. WWCRA Activities

4. Downscaled BCSD CMIP-3 and CMIP-5 GCM Output and Hydrologic Modeling (Bias-Correction Spatial Disaggregation - Coupled Model Intercomparison Project Phases 3 and 5 General Circulation Model) Land Surface Simulation Streamflow Routing Climate Projections Hydrology Projections

5. Online Data Access Climate and Hydrology Projections http://gdo-dcp.ucllnl.org/downscaled_cmip_projections/dcpInterface.html

6. Basin Study Elements Programmatic Requirements Assessment of Water Supply –Historic –Future Assessment of Water Demand –Historic –Future Assessment of Water Supply-Demand Gaps (if any) –Gap analysis Options and Strategies to Address Water Supply-Demand Gaps (if any) –System risk and reliability Trade-off Analysis –Identified options Details at, http://www.usbr.gov/WaterSMART/bsp/require.html

7. Funded Basin Studies 2009 Colorado River Basin Milk/St. Mary Rivers Basin Yakima River Basin 2010 Niobrara River Basin Truckee River Basin Santa Ana River Basin Henrys Fork of Snake River S.E. California Regional Basin 2011 Lower Rio Grande River Basin Santa Fe Basin Klamath River Basin Hood River Basin 2012 Upper Washita River Basin Sacramento-San Joaquin Rivers Republican River Basin Pecos River Basin L.A. Basin 2013, 2014… additional studies For details please visit the Reclamation Basin Studies website, http://www.usbr.gov/WaterSMART/bsp/ Santa Ana River Watershed Klamath River Basin Basin Study examples with groundwater component (later slides) LEGEND

8. Groundwater Availability Currently provides 54% of total water supply in an average year. Projected decreases in precipitation and increases in temperature will decrease natural recharge. Groundwater use projected to increase. Example – Santa Ana River Watershed (Simple GW Tool)

9. SAWPA Groundwater Screening Tool

10. Will a 10% reduction in M&I demand offset the impacts of climate change in my groundwater basin? What is the projected deficit in groundwater storage in my basin by 2050 due to climate change?

11. SAWPA Groundwater Screening Tool –Example: Orange County Coastal Plain Groundwater Basin Estimated decline in basin-averaged groundwater levels due to climate change without management actions to reduce impacts

12. SAWPA Groundwater Screening Tool –Example: Orange County Coastal Plain Groundwater Basin Scenario Comparison: Management alternatives to offset projected impacts on groundwater in Orange County Conservation Gradual reduction of approx. 15% by 2020 (reduce per capita use from ~175 gpd to ~150 gpd) Imported Water Gradual increase in water imports from Colorado River and/or SWP (increase from ~30,000 AF/yr to ~105,000 AF/yr

13. Example – Klamath River Basin Study (Complex GW Tool)

14. In summary, data selections and method choices are throughout the analysis… … choices carry uncertainties, we need to understand those uncertainties, and address them in the planning process. I. Decision-Makers: “Keep it simple.” II. Climate Information Providers: “Here’s the info… use it wisely.” III. Technical Practitioners: “Keep it Manageable.”

15. West Salt River Valley Basin Study Develop a strategy for integration of climate change analysis into West Salt River Valley Basin Study modeling efforts.

16. Climate Change Analysis Decisions Historical period,1950-1999 Future planning time horizon(s) – 1 (30-yr period centered around 2050, [2035-2064] -> index sequential to 100-years for GW model runs) Number of climate change scenarios - 3 (later slide), HD (hot-dry), CT (central-tendency), WW (warm-wet) CMIP-5 Climate Projections per scenario – 10 (used in other Studies) Variables –Precipitation –Temperature –Recharge How was recharge (mountain front) estimated historically in the GW model? Model may not be sensitive to Mountain Front Recharge – hence, may not require adjustment under climate change. –Streamflow Locations and how are stream boundary conditions represented in the GW models? Temporal resolution – monthly to annual Spatial domain and resolution (BCSD climate projection resolution, 1/8 th -degree ~ 12 km) Historical water supply and water demand - to be conducted by Study Partners

17. Example study questions from the Santa Ana River Watershed Basin Study Will surface water supply (local) decrease? Will groundwater availability be reduced? Is Lake Elsinore in danger of drying up? Will the region continue to support an alpine climate and how will the Jeffrey Pine ecosystem be impacted?

18. Example study questions from the Santa Ana River Watershed Basin Study (cont’d…) Will skiing at Big Bear Mountain Resorts be sustained? How many additional days over 95°F are expected in Anaheim, Riverside and Big Bear City? Will floods become more severe and threaten flood infrastructure? How will climate change and sea level rise affect coastal communities and beaches?

19. Example Questions for WESTCAPS Basin Study What is the potential for imported water supply to decrease? –Trigger thresholds in Lake Mead, Colorado River Basin Study What is the potential for increased groundwater pumping, –due to reduced imported water supply? –due to increased demand from population growth or increased ag demand? What are the probabilities of violating the thresholds from GW Management Act of 1980 (Assured Water Supply Act) across the Basin?

20. Climate Change Scenarios Note that the values adjacent to each climate change scenario, filled red circles, represent the respective percentiles of precipitation and temperature changes calculated from the projection ensemble.