1. AWBA Water Supply and Demand Study October 4, 2011 AWBA Meeting

2. Comparison 1997 Base to Base 1997 Base 1997 Reservoir Elevations 15,000 AF Indian Firming Indian Firming thru 2097 Pro Rata CAP/On-River Probability Base Shortage Determination Base 2012 Reservoir Elevation 23,724 AF Indian Firming Indian Firming Thru 2108 Shortage Sharing Proposal Stepped Shortage Determination

3. First Shortage Year Base vs. 1997 Base

4. Shortage Volume Base vs. 1997 Base

5. Number of Shortages Base vs. 1997 Base

6. Credits Remaining Base vs. 1997 Base

7. General Assumptions Starting Reservoir Elevation Jan. 2012 Shortage Triggers CAP Shortage Distribution No Yuma Desalter M&I Firming thru 2097 Indian Firming thru 2108 Indian Firming 23,724 AF

8. Base vs. Scenarios Base On-River/CAP shortage distribution pro rata based on demand Scenarios Director’s Shortage Sharing Recommendation

9. Scenarios Scenario Upper Basin Depletion Schedule On-River Tribal Schedule Lake Mead Shortage Criteria Mexico Shares in Shortage Model Run Completed A AWBA Upper Basin Assumption Ten Tribes Interim Guidelines Extended Yes8/29/2011 B AWBA Upper Basin Assumption Ten Tribes Interim Guidelines Extended No8/29/2011 C AWBA Upper Basin Assumption ADWR 2010-2011 Update Interim Guidelines Extended Yes8/30/2011 D AWBA Upper Basin Assumption ADWR 2010-2011 Update Interim Guidelines Extended No E Upper Basin Schedule Ten Tribes Interim Guidelines Extended Yes8/29/2011 F Upper Basin Schedule Ten Tribes Interim Guidelines Extended No8/29/2011 G Upper Basin Schedule ADWR 2010-2011 Update Interim Guidelines Extended Yes8/29/2011 H Upper Basin Schedule ADWR 2010-2011 Update Interim Guidelines Extended No8/30/2011

10. Shortage Volume Base, Scenario A and Scenario C

11. First Shortage Year Base, Scenario A and Scenario C

12. Number of Shortages Base, Scenario A and Scenario C

13. Credits Remaining Base, Scenario A and Scenario C

14. Shortage Volume Median Traces

15. First Shortage Year Median Traces

16. Number of Shortages Median Trace

17. Credits Remaining Base, Scenario A and Scenario C

18. Discussion