1. Ten Tribes Partnership Tribal Water Study
Colorado River Basin
Ten Tribes Partnership
Tribal Water Study
Colorado River Water Users Association
December 14, 2017

2. Tribal Water Study
Builds on limited assessment of tribal water issues in Colorado River Basin Study
Conducted jointly by Reclamation and the Ten Tribes Partnership
Objectives
Assess current and future water development for tribes of the Ten Tribes Partnership
Assess system impacts resulting from development of tribal water, including to those relying on unused tribal water
Identify tribal water development challenges and opportunities
Study began in January 2014 2 2

3. Study Phases and Tasks – Status
Phase 1: Current Tribal Water
Use
Assessment
Phase 2: Future Tribal Water
Development Assessment
Phase 3: Assessment of System Impacts
Phase 4: Identification & Evaluation of Opportunities & Challenges
Phase 5: Final Report Production
Identify system metrics
Review and incorporate comments from Phase 1-4 draft report sections
Develop data collection template
Complete model (CRSS) enhancements
Identify opportunities and challenges
Select methods to estimate current use
Determine modeling assumptions
Select methods to project future development
Develop draft report sections
Combine into final Study Report
Perform model simulations
Meet with tribal reps to populate template
Rank influencing factors and develop scenarios
Complete reviews
Synthesize and analyze results
Catalog/analyze data
Publish Study Report
Develop draft report sections
Conduct assessment of future development
Develop list of CRSS enhancements
Develop draft report sections
Develop draft report sections
Yellow denotes task is complete 3

4. Current Tribal Water Use
Upper Colorado River Basin
Lower Colorado River Basin 4

5. Potential Future Tribal Water Development
Total Tribal Water Rights including Diversion Claims: 1,753,949 Acre-Feet per Year
Upper Colorado River Basin
Total Tribal Rights Including Diversion Claims: 952,190 Acre-Feet per Year
Lower Colorado River Basin 5

6. System Effects Resulting from Development of Tribal Water
Approach
Findings
Identify tribal water development scenarios
Develop metrics to measure system effects
Configure Colorado River Simulation System (CRSS)
Develop modeling assumptions
Analyze results
Metrics more sensitive to future hydrology than tribal development
Slight decrease in Lake Powell elevations and increase in Lower Basin shortage due to higher rates of tribal water development
Assessment limited due to CRSS spatial representation 6

7. Challenges & Opportunities (potential future actions)
Water Supply Challenges
Agricultural
Water Use Challenges
Administrative and Legal Constraints
Domestic, Commercial, Municipal, and Industrial
Water Use
Establishment
of Continuous, Sustainable Funding
Challenges & Opportunities
(potential future actions)
Environmental Challenges to
the Use of
Tribal Water
Data Collection and Tools
for Water Management
Socioeconomic Considerations
Diverse Geography of Tribal Reservations 7 7

8. 8