1. Ten Tribes Partnership Tribal Water Study
Colorado River Basin
Ten Tribes Partnership
Tribal Water Study
Colorado River Water Users Association
December 15, 2016

2. Tribal Water Study 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
Builds on limited assessment of tribal water issues in Colorado River Basin Study
Conducted jointly by Reclamation and the Ten Tribes Partnership
Study began in January 2014 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
Review and incorporate comments from Phase 1-4 draft report sections
Identify system metrics
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
Publish final Study Report
Rank influencing factors and develop scenarios
Synthesize and analyze results
Catalog/analyze data
Develop draft report sections
Conduct assessment of future development
Develop list of CRSS enhancements
Develop draft report sections
Develop draft report sections
Gray denotes task has started
Yellow denotes task is essentially complete

4. Phase 1: Current Tribal Water Use Assessment
Each tribe provided their unique story of current use
Includes historical use and cultural importance of water
Describes water supplies/infrastructure
Provides a context for tribal water use data
Summarized recent water use in 4 sectors
Irrigated Agriculture and Livestock
Domestic, Commercial, Municipal, and Industrial
Environmental, Cultural, and Recreational
Transfers, Leases, and Exchanges
Described challenges to current water use and future water development

5. Phase 2: Future Tribal Water Development Assessment
Facilitates an understanding of the plausible range of future tribal water development out to 2060
Scenario planning approach similar to one used in the Basin Study but from a tribal perspective
Tribal involvement and thoughtful input was key to envisioning future tribal water development patterns
Outcomes will be used to assess impacts to the Colorado River system from future tribal water development
Used same scenario planning steps used in the Basin Study:
A. Main questions or issues to be addressed in Study
Identify and rank influencing factors – L/T Committee 28 wide-ranging factors could influence how tribes would develop and use water in the future
The factors were grouped into six categories:
Demographic
Land Use and Natural Systems
Infrastructure Development
Economic Development
Social
Governance
Used survey to rank the factors for highly important and highly uncertain and selected key influencing factors – tribal elected officials, technical staff – 64 surveys from all 10 tribes
Develop scenario storylines
Quantify scenarios - develop future water development schedules
Specific, quantitative outcomes of the storylines
2 supply scenarios: Observed Natural Flow, Global Climate Model

6. Key Influencing Factors
Category
Factor Considers Changes in:
Demographics
Non-Indian populations adjacent to reservations
Land Use and Natural Systems
Agricultural irrigation practices
Water quality - physical, chemical, & biological
Financial Resources Available for
Infrastructure Development
(considers both federal and
tribal funding sources)
Resources to expand tribal housing and related infrastructure
Resources to operate and maintain EXISTING storage and delivery infrastructure for irrigation
Resources to construct NEW storage and delivery infrastructure for irrigation
Resources to operate and maintain EXISTING domestic and municipal water infrastructure
Resources to construct NEW domestic and municipal water infrastructure
Economic Development
Water needs for tribal economic development projects
*Preliminary results

7. Key Influencing Factors (cont.)
Category
Factor Considers Changes in:
Governance
Tribal water availability and use due to the resolution and settlement of tribal water rights claims
Laws, policies, and/or regulations to provide increased flexibility for tribes to use tribal water, such as:
Water Banking
Water Marketing
Augmentation and Standby Lease Agreements
Federal, state, and/or regional water administration practices, such as:
More unified accounting approach
Increased measurement and gaging
Improved ability to “shepherd” water
Tribal access to technical resources and expertise for water planning by means of:
Greater allocation of in-house tribal staff and resources
Federal appropriations to support tribal water development and planning
Cooperative efforts with State and regional water entities
The understanding of tribal reserved water rights by federal, State, other governmental agencies and the public at large
*Preliminary results

8. Scenario Storylines / Themes Developed
Title
Theme A
Current Water Development Trends
Current trends in on-Reservation water development, governance, funding, and resolution of tribal claims remain the same. B
Slow Water Development Trends
Decreased flexibility in governance of tribal water, levels of funding, and resolution of tribal claims slow tribal economic development. This results in a decline in the standard of living and delays resolution of tribal claims.
C1 and C2
Rapid Water Development Trends
Increased flexibility in governance of tribal water allows innovative water development opportunities and increased funding availability leads to tribal economic development. This results in an increase in the standard of living, thereby contributing to the fulfilment of the purpose of the Reservation as a homeland and supporting the future needs of tribal communities. Scenario C1 considers partial resolution of claims and/or implementation of decreed or settled rights; and Scenario C2 considers complete resolution of claims and implementation of decreed or settled rights.
*Preliminary results

9. Preparation of Future Water Development Schedules
Each tribe considered their current use and prepared future water development schedules reflecting how the storylines will affect their future water development
Focused on 4 water use sectors:
Irrigated Agriculture and Livestock
Domestic, Commercial, Municipal, and Industrial
Environmental, Cultural, and Recreational
Transfers, Leases, and Exchanges
In general, Upper Basin tribes considered future development at a sub-basin (tributary) level

10. Example: Southern Ute Indian Tribe Future Water Development and Use
Notes/Assumptions for Future Development (Scenario A):
Agriculture:
Assume total of 24% increase by 2040 and additional 15% by 2060 on San Juan, Pine, Piedra, and Florida Rivers
Assume efficiencies remain the same
DCMI:
Assume additional 500 AF use on Animas by 2040, 1000 AF by 2060
Assume doubling of current use on Pine River by 2060
Assume AF on Road by 2060
Assume no change from current use on San Juan, Piedra, Florida, and La Plata through 2060
Env/Cult:
Assume 5,500 AF use on Pine River by 2060
Trans/Leas:
Assume 700 AF is transferred/leased from Animas by 2060
Notes/Assumptions for Future Development (Scenario B):
Development scheduled is based on the high-level quantification guidance developed by Workgroup. Scenario B was normalized to Current Trends, and then 1/2 of the normalize adjustment was applied to SUIT Current Trends Scenario (Scenario A)
Ag use drops due to failing infrastructure; DCMI continues to grow (slower) because of area non-tribal demand.
*Preliminary results

11. Example: Southern Ute Indian Tribe (cont.)
*Preliminary results

12. Compiled Demand Scenarios
Upper Basin
- Current use tribal diversions are 731 kaf (447 kaf depletions), approximately 8% of total upper basin diversion (9% of total upper basin depletion)
- By 2060 upper basin diversion range from – maf ( maf depletions) across all scenarios , approximately 10% – 13% of the total Upper Basin diversions (11% - 14% of total Upper Basin depletions)
-- Diversion range is ~300 kaf (~190 kaf depletion range) across scenarios (B vs C2)
-- Total Upper Basin quantified tribal diversions are maf
-- Total Upper Basin quantified and claims tribal diversions are maf
Lower Basin
- Current use tribal depletions are 464 kaf, approximately 6% of total lower basin depletion
- By 2060 tribal depletions range from kaf across all scenarios, approximately 6% - 10% of the total Lower Basin depletions
-- Depletion range is ~235 kaf across scenarios (B vs C2)
- By 2060 tribal diversions range from 866 – 945 kaf,
-- And additional 7 – 86 kaf of additional development remains
*Preliminary results

13. Compiled Demand Scenarios
Official CRSS schedule
Upper Basin
- Current use tribal diversions are 731 kaf (447 kaf depletions), approximately 8% of total upper basin diversion (9% of total upper basin depletion)
- By 2060 upper basin diversion range from – maf ( maf depletions) across all scenarios , approximately 10% – 13% of the total Upper Basin diversions (11% - 14% of total Upper Basin depletions)
-- Diversion range is ~300 kaf (~190 kaf depletion range) across scenarios (B vs C2)
-- Total Upper Basin quantified tribal diversions are maf
-- Total Upper Basin quantified and claims tribal diversions are maf
Lower Basin
- Current use tribal depletions are 464 kaf, approximately 6% of total lower basin depletion
- By 2060 tribal depletions range from kaf across all scenarios, approximately 6% - 10% of the total Lower Basin depletions
-- Depletion range is ~235 kaf across scenarios (B vs C2)
- By 2060 tribal diversions range from 866 – 945 kaf,
-- And additional 7 – 86 kaf of additional development remains
*Preliminary results

14. Phase 3: Assessment of System Impacts
Purpose
Determine Basin-wide impacts resulting from plausible tribal water development scenarios
Approach
Colorado River Simulation System (CRSS) Model
Four future water development scenarios
A, B, C1, and C2
Two supply scenarios
Observed Natural Flow (ONF); Global Climate Model (GCM)
Two policy assumptions for past 2026
Revert to FEIS No Action Alternative (NA), Interim Guidelines Extended (IG)
Metrics to indicate Basin impacts from supply and tribal water development scenarios
3 Development Scenarios with 4 development outcomes
Development
Current Water Development Trends
Slow Water Development Trends
Rapid Water Development Trends
Partial Resolution of Claims
Complete Resolution of Claims and Implementation of Settlement Rights
Upper Basin Non-Tribal demands are per the 2007 UCRC schedule
Lower Basin Non-Tribal demands are per the Interim Guidelines Final EIS
ICS Schedules updated in 2016
2017 demands set to water use schedules in the August 24-Month Study
Lower Basin depletions do not exceed 7.5 maf apportionment
Supply
Observed Natural Flow (ONF)
Resampled using the “Indexed Sequential Method”
107 Traces
Downscaled GCM Projected Trends and Variability (GCM)
Utilizes climate projections from CMIP3
Downscaled and bias corrected as per the Basin Study
112 Traces
Modeling Limitations
CRSS is not an accounting model
Cannot track priorities
Cannot see impacts on per-user basis
Cannot assign Lower Basin shortage at Lake Mead below 1,025 feet
Shortage beyond that scheduled in the Interim Guidelines
Modeled as hydrologic shortage
May not properly assign Tribal v. NonTribal shortage in the Upper Basin

15. Metrics from CRSS Upper Basin Lower Basin Nontribal deliveries
Lake Powell inflow and water level elevation
Shortage frequency and volume
Nontribal and tribal separated
In Upper Basin and major sub-basins
Lower Basin
Lake Mead water level elevation
Nontribal and tribal combined
In Lower Basin
Nontribal deliveries

16. Approach for Additional Analysis
Upper Basin
Determine how shortages were distributed to tribal vs. nontribal users during representative dry year (2008)
Explore how lessons learned from the representative year analysis could apply to future situations
Lower Basin
Explore how users are impacted during hydrologic shortage
Shortage distribution discussed qualitatively based on water right priority dates

17. Preliminary Findings – Upper Basin
Lake Powell Inflow
Maximum difference in inflows across all scenarios was 290 kaf with ONF hydrology, 260 kaf with GCM hydrology
Inflow was more sensitive to hydrology than tribal development
Lake Powell Water Level Elevation
By 2060, elevation differences across the scenarios grew to 18 feet on average and increased to 31 feet at lower elevations (ONF hydrology)
Shortage
Upper Basin shortage volumes and frequency are more sensitive to hydrology than tribal development

18. Preliminary Findings – Lower Basin
Lake Mead Water Level Elevation
By 2060, elevation differences seen across the scenarios were as large as 9 feet on average
Shortage
Little variation seen across scenarios, shortage responds primarily to hydrology
Slightly increased instances of shortage result due to higher Upper Basin tribal development schedules A, C1, and C2
Nontribal Deliveries
Scenario B has less of an impact on nontribal deliveries than Scenarios A, C1, and C2
When projecting with GCM hydrologies, less variation in deliveries is seen across development scenarios

19. Phase 4: Identification & Evaluation of Opportunities & Challenges
Phase 4 is a discussion of opportunities and challenges related to future use and/or development of tribal water
Committee synthesized challenges identified by each tribe into 9 categories:
Establishment of continuous, sustainable funding
Administrative and legal constraints
Responding to water supply challenges
Agricultural water use
Domestic, commercial, municipal, and industrial water use
Environmental challenges to water use
Socioeconomic considerations
Diverse geography of tribal reservations
Data collection and tools for water management
Committee identified opportunities and potential actions

20. Next Steps Anticipate publishing study report in early 2017
Report will be available at Tribal Water Study web page: