Lee Ferry Projected Flows from Basin Study

Obs Max - Dash

Obs Min - Dash

Max Dark Shading 25-75%Light Shading 10-90%Horizontal Solid Line – Historical AverageBold Dark Line – 21st Century MedianRed Line – One Representative Trace

Figure B-45 Tech Appendix BEach Year has 112 Projections

At 45 maf/year flood control may be an issue

-9%

Bottom Line: 75% Models Show Declines, Median Decline -9% at Mid - Century

New CMIP5 Model Runs Show Similar Results for CRB

Seager et al., NCC 2012

Annual % Runoff Changes by Season for Colorado River at Mid Century

Annual Runoff Changes by Model at Mid Century

10% Less Annually

Almost all models show declines

Increased Demands Due to Climate Change

Bottom Line: A Variety of Demand Increases Possible by Mid-Century, Average is 4%

4% More Annually

Thoughts on Supply vs Demand Strategies

• Like DOI Leaders, I believe new Supply Options Limited• Have now reached the era where new thinking needed• How do use existing and substantial supplies to optimize 3 outcomes:

economic, social, environmental needs

• Reconsider “We’re running out water” meme• Everyone Loves to Play this Game:

• press, providers, scientists, NGOs• Pernicious: having a harmful effect in gradual or subtle way• Two variants of this game: (1) no water at all vs (2) reduced supplies• With Climate Change, ~85% of 15 maf = 12.75maf is still lots of water

• Risk Management, Economics, Values to Guide Us• Efficiencies, Conservation, Reuse of Existing Supply are very safe bets; the

safest bets we have, also the cheapest and least environmentally harmful• Development of New Supplies based on unknown hydrology is the riskiest

bet in terms of yield, cost, environmental harm