Enhancing Winter Orographic Snowfall in the West Through Cloud Seeding

Technical Lead: 
David Reynolds (CIRES)
David Keeney (Bureau of Reclamation), Levi Brekke (Bureau of Reclamation)

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From the 1960s through the 1980s the Bureau of Reclamation was involved in a variety of weather modification initiatives in the west including Project Skywater which included the Colorado River Basin Pilot Project, the High Plains Experiment, and the Sierra Cooperative Pilot Project to name a few. After significant decline in activity through the 1990s, Congress authorized funding within the Weather Damage Modification Program in 2002 and 2003. The Bureau of Reclamation primarily stopped participating in weather modification, or cloud seeding, activities in 2005 because of lack of programmatic appropriations specified for the activity in addition to uncertainties about scientific efficacy as described within the National Research Council’s 2003 report, “Critical Issues in Weather Modification” (NRC 2003) as well as questions about legal and liability issues.

Continuing drought conditions and stakeholder interest has led Reclamation to take an updated look at the effectiveness of cloud seeding for the enhancement of winter precipitation and snowpack in the western United States.

Reclamation’s Science Advisor through the Research and Development Office is leading the process to take this updated look. A key component involves developing a science synthesis from recent literature, and evaluating progress to address key scientific uncertainties described in NRC 2003. CIRES was asked to complete this componet of the study and constitutes the project reported on here.  

The synthesis was developed during 2014-2015.  External input was invited throughout the process.  Opportunities included a November 2014 perspectives-gathering workshop involving 55 participants from 25 Federal and non-Federal organizations, and review of the draft science synthesis where the document was classified as "influential scientific information" per Reclamation peer review policy. 



  • A comprehensive literature review and scientific synthesis, which included review by both Bureau of Reclamation personnel and external reviewers, was completed.  
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