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<br />snowpack in the Colorado River Basin. The objective was to obtain scientific proof that <br />properly conducted seeding of winter orographic clouds in the Colorado River Basin will <br />beneficially and cost-effectively enhance snowpack and subsequent runoff without <br />deleterious effects to the environment. The program was designed to produce results in <br />the shortest time, for the least cost, and with the highest probability of success. Its total <br />cost was estimated at $70 million ( 1993 dollars). See Department of the Interior, 19931 <br />for a detailed plan for CREST. <br /> <br />The original CREST envisioned physical and statistical evaluations conducted at two <br />sites in the Basin - the Grand Mesa of west-central Colorado and the Wasatch Plateau of <br />central Utah. The program was designed in two phases - the first emphasized physical <br />process studies and direct snowfall measurement (3 years); the second was seeding with <br />statistical modeling (4 years), preceded by one year of environmental compliance and <br />project planning. The hypothesized result after cloud seeding all suitable storms was an <br />estimated 10 to 15% increase in seasonal snowfall, resulting in a similar increase in <br />streamflow. In 1993 the State of Colorado declined to participate in the test, and it did <br />not move forward as proposed. <br /> <br />Some seeding trials were conducted on winter clouds over the Grand Mesa and there was <br />a repeated indication of precipitation increases in response to seeding. However, the <br />work did not include a statistical component for evaluation of precipitation so the <br />increases are not certain. Reclamation then did some work on the Mogollon Rim in <br />Arizona for two winters. After that some of the federal funds were transferred to the <br />National Oceanic and Atmospheric Administration which did some additional seeding on <br />the Wasatch Plateau. Finally, remaining funds were used for the North Platte River Basin <br />Headwaters Project, which demonstrated promise for recently developed technologies; <br />unfortunately that river is not in the Colorado River Basin. Nevertheless, some of the <br />lessons learned are still applicable and were used in a recent feasibility study. (DOl, <br />2000). <br /> <br />National Oceanic and AtmosDheric Administration (NOAA). From 1986 through 1995, <br />the NOAA Federal-State Atmospheric Modification Program funded weather <br />modification research in six states, at a level of about $500,000 per year per state. The <br />funding was used for research components, and was split between winter orographic and <br />warm season programs and included cloud seeding experiments using both silver iodide <br />and liquid propane. The breadth of the' research was significant and several advances <br />related to winter orographic cloud seeding are worth noting. In Arizona a new polarized <br />radar technique was used to track the dispersion of airborne seeding plumes and the <br />evolution of seeded ice crystals in naturally precipitating clouds. Seeding trials using <br />ground releases of silver iodide and propane on the Wasatch Plateau of Utah produced <br />considerable direct evidence of ice crystal and snowfall enhancement. In Nevada and <br />California a new dual-tracer chemical technique was developed to assess the impact of <br />seeding on winter snowpacks. Several state projects used numerical models, verified by <br />observations, to study the transport and dispersion of seeding material over mountainous <br /> <br />'p.19 <br /> <br />-7- <br />