Basin States Agreement for Cooperative Weather Modification Program

1. Basin States Agreementfor CooperativeWeather Modification Program Presentation to the Western States Water Council November 17, 2006 Tom Ryan Metropolitan Water District of Southern California

2. Weather Modification (WxMod) in the Colorado River Basin • Winter orographic cloud seeding • Precipitation augmentation and snowpack enhancement • Increase in system runoff

3. WxMod Background • 1940s: Started in the U.S. • 1951: Projects in over 30 countries • Overselling of capabilities and unrealistic expectations • 2006: Improved methods • Scientific • Operational

4. Winter Snow Augmentation Other Programs States with WxMod Programs

5. Current Users of WxMod • Currently 100 programs in 24 countries and 10 states • Ski areas, power utilities • Water resources agencies • Conservation and irrigation districts

6. Five Programmatic Themes in WxMod • Interference with nature • Cloud rustling • Potential environmental impacts • Potential health effects • Increased snowload

7. Interference With Nature • Misconception and miniscule compared with inadvertent WxMod • The Industrial Revolution • May reverse ongoing negative effects • Societal attitudes toward “interfering with nature” and WxMod projects

8. Cloud Rustling • Downwind effects misconception • WxMod’s objective is to affect spatial and temporal distribution of precipitation • “Robbing Peter to pay Paul” or enhancing precipitation at downwind expense

9. Potential Enviro. Impacts • 20 years of studies of Agl on: • Physical & biological • Aquatic systems, soils & vegetation • Strong studies with credible results • Newer methods & regs. suggest: • caution complete acceptance • Consider cumulative & monitoring

10. AgI Potential Health Effects • Concentrations • EPA drinking water quality rec. of 0.1 mg/l • U.S. Public Health Service level of 0.5 mc/l • Seeded rainfall is 0.1 mc/l • Human effects from precipitation • Silver relatively low order of toxicity • Far greater silver exposure from tooth fillings • Far greater iodine from salt used on food

11. Increased Snowload • Avalanche • Suspension criteria • Snow removal • Small incremental increase • Flooding potential • Surveys, coordination • Buildings • Current building codes based on snowloads • Crop yield / pasture value / feed • 0-3 days longer, w/i range of normal variability • Economic trade-offs • Snow removal & longer cover v. tourism & rec.

12. Liability • Statutory • Federal requires records & reporting • Colorado and Utah statutes • Nuisance or trespass • Governmental immunity, permits required • Case • Few published liability suits, fewer have been successful • Harm and causation

13. Conclusions on Liability • Sparse and unsettled case law • Statutory limitations • Governmental immunity, nuisance & trespass • Conclusions • Despite statutory limits on liability, suits possible, harm & causation primary hurdles • Insurance & indemnification

14. Water Year 2006 San Juan Mtns. Trial Extension • Five Basins in Southwestern Colorado • Partners: • Lower Basin States, CWCB and SWCD • $35,000 seeding; $10,000 evaluation • Estimated 31,000 af was generated

15. Proposed WY07 Activities • $300,000 budget • Cost-shared by AZ, CA, NV • Addition to Upper Basin programs / budget • Operations • Extend projects in Colorado, Utah • Evaluation • Physical & statistical studies in Colorado, Utah • Research • Instrument deployment in Wyoming

16. Proposed WY07 Activities

17. 5-Year Plan for Cooperative WxMod Program • Technical staff from Basin States • Roadmap of activities and studies • Integrates previous work • Expansion, optimization, evaluation • Prepares for fully developed long-term operations • Draft Winter ‘07, Final Summer ‘07

18. Summary • Advances in technology since 1940s • Inadvertent WxMod is occurring • Potential negative effects of five themes presented none to minimal • Water Year 2006 trial extension • Water Year 2007 activities starting • Basin States Cooperative Program