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I I I I 1 I I I I I I I I I I I I I I The Weather Modification Advisory Board (l978:l25) states that cloud seeding is not designed nor exp:cted to eliminate drought. Sonka (l979:48) also writes that weather ma~ification is not eXPe<:;:ted to eliminate drought. He expresses the opinion, however, that the "value of even relatively small increments of moisture for agricultural production and water supplies may be substantial during such periods." Yevjevich (l978:l68) states that "when weather modification is most needed, the potential of air masses to respond . . . is the lowest." He concludes that "it is very irrportant to study . the number of storms in dry years and the average yield per storm." Howell and Grant (l972) present evidence that suggests that seeding opportunity may exist during dry - periods. They emphasize that a seeding program should involve cooperc:Ltion on legal, economic, legislative and social levels, as well as at the! level of water-systems operation~. DROUGHT IN COLORADO Drought is a recurrent phenomenon in the western and central United States. Colorado is particularly susceptible to drought because its growing population places increC:lsing demands upon its supplies of water. In the winter of 1976-77, Colorado experienced its first period of extreme water shortage since the early 1950s. By the end of January 1977 snowfall was at record low le'iTels in many mountain areas. Runoff from melting mountain snows, which under normal conditions provides approximately 70 percent of th'e state's water, was minimal. Record lows were recorded at two-thirds of the checkpoints on major Colorado rivers (Gray, 1979: 1) . Although rains returned in the surmner, reservoir storage levels fell dramatically and soil moisture levels remained low in many areas. It was feared that if the following winter were as dry, Colorado would suffer disastrous conseque~nces. .5