1. Colorado River Basin Water Supply and Demand Study NIDIS update February 24, 2011 Boulder, CO

2. Colorado River Basin Water Supply and Demand Study Two-year, $2 million study cost shared by Reclamation and the Basin States Assess future water supply and demand imbalance Assess risks to all basin resources Investigate options and strategies to mitigate impacts A transparent, collaborative study with input from all stakeholders Email: ColoradoRiverBasinStudy@usbr.gov Website: http://www.usbr.gov/lc/region/ programs/ crbstudy.html

3. Study Area –Colorado River Basin and those adjacent areas of the Basin States that receive Colorado River water Cost-Share Partners –Arizona Department of Water Resources –(California) Six Agency Committee –Colorado Water Conservation Boar –New Mexico Interstate Stream Commission –Southern Nevada Water Authority –Utah Division of Water Resources –Wyoming State Engineer’s Office –Reclamation (LC and UC Regions) Colorado River Basin Water Supply and Demand Study

4. Annual Colorado River Water Supply & Use

5. Study Outreach Colorado River Basin Water Supply & Demand Study Hydropower Western, CREDA. others Ecosystem Demands NGO collaborative. others Endangered Species FWS, others Other General public, other interested stakeholder groups Native American Tribes and Communities Lower Basin, Upper Basin Water Deliveries Water Purveyors (agriculture, M&I use) Recreation NPS, Concessionaires, others

6. Study Phases and Tasks Phase 1: Water Supply Phase 2: Water Demand Assessment Phase 3: System Reliability Analysis Phase 4: Development & Evaluation of Opportunities 1.1 – Select Methods to Estimate Current Supply 1.2 – Select Methods to Project Future Supply 1.3 – Conduct Assessment of Current Supply 1.4 – Conduct Assessment of Future Supply 2.1 – Select Methods to Estimate Current Demand 2.2 – Select Methods to Project Future Demand 2.3 – Conduct Assessment of Current Demand 2.4 – Conduct Assessment of Future Demand 3.1 – Identify Reliability Metrics 3.2 – Estimate Baseline System Reliability 3.3 – Project Future System Reliability 4.1 – Develop Opportunities 4.2 – Evaluate and Refine Opportunities 4.3 – Finalize Opportunities 3.3.5-3.3.8 – Project Future Reliability with Opportunities Formulate Approach to Include Uncertainty Develop Future Supply and Demand Scenarios

7. Draft Water Supply Storyline Themes Observed (O) –Theme: Historic instrumental period for streamflow represents suitable trends and variability for characterizing the future Direct Paleo (DP) –Theme: Paleoclimate period offers a more expansive understanding of streamflow variability that may be more representative of future variability Paleo Conditioned (PC) –Theme: Inter-annual variability of paleo reconstructions is believed to be more representative of future variability, but streamflow magnitudes are believed to best represented by the instrumental period Climate Projection (CP) –Theme: Future climate and streamflow variability is represented through global climate models and simulated hydrologic conditions driven by the results of these models

8. Global Climate Models Methodology for Incorporating Climate Projections in Future Supply Emission Scenarios (3 scenarios: A2, A1b, B1) Bias Correction & Spatial Downscaling (112 downscaled projections) Hydrologic Modeling (112 downscaled projections) Systems Modeling (112 traces) 16 GCMs

9. Current “Best” Estimate Natural Flow Conditions at Lees Ferry 2011 – 2060 Period Mean Annual Flows Box represents 25 th – 75 th percentile, whiskers represent min and max, and triangle represents mean of all traces DRAFT – SUBJECT TO CHANGE 1988 – 2007 period mean

10. Draft Demand Storyline Themes “A”: Current Trends –Theme: Growth, development patterns, and institutions continue along recent trends “B”: Economic Slowdown –Theme: Low growth with emphasis on economic efficiency “C”: Expansive Growth –Theme: Economic resurgence driven by population growth and energy needs C1 branch to slower technology adoption C2 branch to rapid technology adoption and slight increase in social values “D”: Enhanced Environment and Healthy Economy –Theme: Expanded environmental awareness and stewardship with growing economy D1 branch to current growth trends D2 branch to higher growth and technology

11. Integration of Supply and Demand Scenarios Recent Trends Supply Scenarios (multiple realizations for each scenario) Demand Scenarios Current Trends PR C A B D O PC CP Climate indexing for demands

12. Colorado River Simulation System (CRSS) Comprehensive model of the Colorado River Basin Developed by Reclamation (early 1970s) and implemented in RiverWare TM (1996) Primary tool for analyzing future river and reservoir conditions in planning context (NEPA EIS) A projection model, not a predictive model Excellent for comparative analysis Gives a range of potential future system conditions (e.g., reservoir elevations, releases, energy generation) Simulates on a monthly timestep over decades Operating policy is represented by “rules” that drive the simulation and mimic how the system operates

13. Metrics are measures that indicate the ability of the system to meet the needs of Basin resources Metrics will be used to quantify the impacts to Basin resources from future supply and demand imbalances System Reliability Metrics Metrics Resource Categories Depletions Electrical Power Resources Water Quality Flood Control Recreational Resources Ecological Resources

14. Study Phases and Tasks Phase 1: Water Supply Phase 2: Water Demand Assessment Phase 3: System Reliability Analysis Phase 4: Development & Evaluation of Opportunities 1.1 – Select Methods to Estimate Current Supply 1.2 – Select Methods to Project Future Supply 1.3 – Conduct Assessment of Current Supply 1.4 – Conduct Assessment of Future Supply 2.1 – Select Methods to Estimate Current Demand 2.2 – Select Methods to Project Future Demand 2.3 – Conduct Assessment of Current Demand 2.4 – Conduct Assessment of Future Demand 3.1 – Identify Reliability Metrics 3.2 – Estimate Baseline System Reliability 3.3 – Project Future System Reliability 4.1 – Develop Opportunities 4.2 – Evaluate and Refine Opportunities 4.3 – Finalize Opportunities 3.3.5-3.3.8 – Project Future Reliability with Opportunities Formulate Approach to Include Uncertainty Develop Future Supply and Demand Scenarios

15. Colorado River Basin Water Supply and Demand Study http://www.usbr.gov/lc/region/programs/crbstudy.html NIDIS update February 24, 2011 Boulder, CO

16. Extra Slides

17. Demographics & Land Use Economics & Technology Social & Institutional D2 A D1 C1 B C2 Graphical Depiction of Driving Forces Categories and Scenarios Today

18. Categorization and Selected Driving Forces for Storyline Development General Driving Force Category Key CRBS Driving Forces Identified in Survey Natural Systems (Hydroclimate)  Changes in streamflow variability and trends [1]  Changes in climate variability and trends (e.g. temperature, precipitation, etc.) [2] Demographics & Land Use  Changes in population and distribution [4]  Changes in agricultural land use (e.g. irrigated agricultural areas, crop mixes, etc.) [5] Technology & Economics  Changes in agricultural water use efficiency [8]  Changes in municipal and industrial water use efficiency [9]  Changes in water needs for energy generation (e.g. solar, oil shale, thermal, nuclear, etc.) [12] Social & Governance  Changes in institutional and regulatory conditions (e.g. laws, regulations, etc.) [10]  Changes in flow-dependent ecosystem needs for ESA-listed species [13]  Changes in other flow-dependent ecosystem needs [14]  Changes in social values affecting water use [15]  Changes in water availability due to tribal water use and settlement of tribal water rights claims [17]