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 Average Bold Dark Line – 21 st Century Median Red Line – One Representative Trace Figure B-45 Tech Appendix B Each 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