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approach and position; evaluation network; and general aspects of recognition-- seeding contract and other project support. 132. Bureau of Reclamation, 1971, Colorado River Basin project in cloud seeding, 4 year weather modification experiment in sW Colorado for augmenting water supplies (final environmental impact statement): Washington, D.C., Bureau of Reclamation, 33 p. [Available from National Technical Information Service, Springfield, V A 22161 as NTIS Report PB-21O 086-F.] The project is a test of large-scale application of cloud seeding techniques for increasing snowfall in mountainous areas, using the San Juan Mountain area in southwestern Colorado as a test area. There will be four winter seasons of seeding, beginning with the 1970-71 season. Seeding is being conducted over a 1,300-square- mile target area of the 3,300-square-mile San Juan Mountain project area. The Colorado State University experiments conducted at Climax and at Wolf Creek Pass area of Colorado produced solid evidence that winter cloud seeding with ground- based silver iodide generators can produce an average snowfall increase of 10 to 30 percent. These findings confirm earlier estimates that about 2 million acre-feet more streamflow would be possible from target areas in the Upper Colorado River Basin by cloud seeding. There is concern with regard to the hazards posed by weather to residents and visitors in this mountainous area. In recognition of the social response to dangers posed by avalanches, especially in the Ouray-Silverton- Telluride area, the Bureau decided that there would be no seeding initially in subareas 3 and 4. Additional snow should not significantly increase snow removal costs. There may be some concern over the potential contamination of the environment by the silver iodide used as the seeding material in this experiment. Silver concentrations measured in precipitation from seeded storms range from 0.000001 to 0.00176 parts per million. Although several studies have concluded that there is no direct hazard to humans from the use of silver iodide as a seeding agent, additional studies are needed to determine if there could be ecological effects of large-scale, long-term use of silver iodide. The ecological monitoring program includes an investigation of residual and long-range accumulation effects of the silver iodide. 133. Bureau of Reclamation, 1971, Crystal Dam, reservoir, and powerplant, Curecanti Unit, Colorado River Storage Project (draft environmental impact statement): Washington, D.C., Bureau of Reclamation, 32 p. [Available from National Technical Information Service, Springfield, V A 22161 as NTIS Report PB-202 071-D.] Crystal Dam is the final feature of three units planned to generate electrical power from available head in the Gunnis.on River between Gunnison, Colorado, and the Black Canyon of the Gunnison National Monument. The first two, Blue Mesa and Murrow Point, are completed. Releases from Crystal will provide minimum flows in the Gunnison River which have not been historically available. Major environmental impact will be from removal of concrete aggregate and other channelization work in the river channel. Six and one-half miles of quality stream fishery habitat in the Gunnison River will be inundated. Turbidity in the river will be increased slightly during construction from aggregate processing and channel excavation. Stabilized permanent flows in the Gunnison River will occur below the dam. Inundation will occur in a highly scenic canyon area. 28 Bibliography, Indices. and Data Sources of Water-Related Studies. Upper Colorado River Basin, Colorado and Utah. 1872-1995