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<br />SEP-29-97 MON 03:36 PM TRC NORTH AMERICAN WX <br /> <br />FAX NO, 801 972 3813 <br /> <br />p, 09 <br /> <br />(1955) stated the hypothesis that winter mountainous stonns that <br />contained supercooled water could be 'seeded" with certain materials to <br />produce additional ice crystals that could grow into additional <br />snowflakes which would augment the natural stonn precipitation. <br /> <br />The Climax research program, conducted in two phases in the central <br />Colorado Rockies (Mielke, et al., 1981), indicated increases in natural <br />winter snowfall of approximately 25 percent in warm topped (warmer <br />than -20"C) orographic clouds. The Climax research program utilized <br />ground based silver iodide generators quite similar to those proposed to <br />be used on this program. <br /> <br />Que.<.tions 8 & 9: The type of proposed operational program has been the subject of <br />extensive research conducted by the Denver offices of the Bureau of <br />Reclamation under the program 'Skywater.' The Bureau has studied <br />the numerous potential impacts of winter weather modifi~tion <br />programs. A generic environmental impact statement has been <br />prepared (Higginson, 1977). This statement declared negative <br />environmental impacts from this program. <br /> <br />For example, the question of the toxicity of silver Iodide used as a cloud <br />seeding agent has been studied to the extent that a complete book has <br />been written on the subject (Klein, 1978). Quoting from the Summary <br />of this book. . . <br />". . .the major environmental concerns about <br />nucleating agents (effects on plant growth, <br />game animals, and fish etc.) appear to represent <br />negligible environmental hazards.' <br /> <br />Each NAWC generator will only emit approximately eight (8) grams of <br />silver iodide )Jer hour. This minute amount of material is spread over a <br />large area suc:h that the seeding material becomes undetectable by even <br />the most sensitive chemical analysis techniques a few tens of miles <br />downwind (Warburton, et al., 1979). <br /> <br />The question of the potential for a reduction in precipitation downwind <br />of the target area is often raised regarding weather modification <br />programs. The National Science Foundation funded a workshop In <br />1977 to examine this question. Quoting from a summary of this <br />workshop (Brown, et al., 1978). . . <br /> <br />"The 'better quality' evidence available from <br />mostly a posteriori analysis of past randomized <br />seeding programs suggests that precipitation <br />changes in extended areas tend to be of the <br /> <br />r:ldaGlpcra';I.wpd <br /> <br />3 <br />