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EXECUTIVE SUMMARY I <br />This document presents a proposed weather modification program of applying operational cloud seeding <br />technology to enhance the winter snowpack in high - elevation mountainous areas of north - central <br />Colorado and southern Wyoming (hereafter Headwaters Region) and consequently, provide additional <br />streamflow to the North Platte River. Government officials and others are looking at several options for <br />adding water to the river. The Secretary of the Interior is charged with the responsibility for <br />development of the water resources of the Colorado River Basin (Colorado River Basin Project Act, <br />1968; Public Law 90 -537), the protection of water quality (Colorado River Basin Salinity Control Act, <br />1974; Public Law 93 -320), and the transfer of precipitation management technology (Reclamation States <br />Emergency Drought Relief Act, 1991; Public Law 102 -250). Several options are under consideration to <br />provide additional water including reservoir management. Cloud seeding technology improvements in <br />the past 20 years now provide a logistically feasible and cost - effective option to enhance fresh water <br />resources in some mountain watersheds of the western United States. <br />The proposed program consists of two principal components, a cloud seeding design phase and the <br />operational seeding phase. Lessons learned in previous cloud seeding studies indicate that each area <br />presents hurdles to cloud seeding that are site specific. The proposed three -year design phase is aimed at <br />conducting field and modeling studies to determine the proper approach, equipment, and installation sites <br />appropriate for the Headwaters Region. Additionally, the design phase will enable dealing with <br />environmental compliance and the conduct of associated studies. No cloud seeding can take place until <br />compliance is achieved. Because average winter precipitation is expected to increase in the Headwaters <br />Region from cloud seeding, environmental compliance efforts for a possible Environmental Assessment <br />or Environmental Impact Statement are estimated to require three years for completion. Intended benefits <br />of a three -year design effort include the development of an evaluation design proper for operational <br />seeding in the Headwaters Region. The operational seeding period is structured for 10 years (equipment, <br />permits, environmental compliance) and will involve automated cloud seeding systems that largely self - <br />determine when seeding is appropriate and then proceed to treat clouds. Data collection is also expected <br />to be largely automated. All data collection and cloud seeding system types should be installed and tested <br />in the design phase. <br />Regarding the scientific support for cloud seeding, current policy statements of the American <br />Meteorological Society and the World Meteorological Organization state that statistical analyses of some <br />cloud seeding programs have suggested mountain snowfall increases of 10 to 15 percent per winter. <br />Cloud seeding experiments conducted and /or supported by the Bureau of Reclamation in the 1980 -90s <br />have contributed sorely needed physical measurements and analyses that documented cloud and <br />precipitation responses to cloud seeding and indicated that specific areas can be targeted for treatment <br />effects. These studies along with the substantial improvement in computer modeling of weather and <br />clouds provide methodology that can be applied to seeding winter clouds in the Headwaters Region and <br />expect to obtain measurable additional precipitation. <br />Seeding trials conducted on winter clouds in the Grand Mesa of west - central Colorado and the Wasatch <br />Plateau of Utah repeatedly indicated a precipitation increase response to seeding (see appendix A, <br />sections 7 and 8, for details and references). Those studies did not include a component of statistical <br />evaluation of precipitation, but were rather structured for physical measurements. To develop estimates <br />of additional water from cloud seeding in the Headwaters Region, enhancement results of about 25 1 <br />Vi <br />