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<br />conclusion was that the Western Kansas Weather Modification Program had little or no <br />effect on seasonal precipitation. Interpretation of the results of this study need to be <br />made with considerable caution because of reasons mentioned above. Also, the failure <br />to select a control area that extended to the eastern border of the target area made it <br />impossible to determine if the observed precipitation decline in the target area from 1948- <br />1974 to 1975-1985 was more or less extreme than that of a potential eastern control area. <br /> <br />Fifth Evaluation <br /> <br />A fifth evaluation study entitled "Analysis of a Cloud Seeding Program in Southwestern <br />Kansas, 1975-1990"5 was prepared by Ms. Susan Hurt and Dr. William F. Simpson, <br />Emporia State University. <br /> <br />U.S. Department of Commerce climatological data was used as a source for precipitation <br />data for the period May-August for 1960-1990. One station was chosen from each of <br />seven counties to represent the target area. It should be .noted that three of the counties, <br />selected to represent the target area, did not participate in cloud seediilg activities during <br />one of the years during the 1975-1990 cloud seeding evaluation period. <br /> <br />Five stations were chosen to represent the control area. In Oklahoma, stations chosen <br />to represent the control area were in Beaver and Texas counties. It should be noted that <br />cloud seeding activities took place in Texas County each year from 1973-1980 and in <br />Beaver County from 1972-1975. Also, additional cloud seeding activities may have <br />occurred in these counties in the 1950-1969 time period and in the 1982-1990 time <br />period. In Colorado, three stations (located in Kiowa, Prowers and Baca counties) were <br />chosen to represent the control area. No cloud seeding operations are known to have <br />occurred in these three courlties in Colorado. <br /> <br />The study results showed that the difference between the control area and target area <br />average seasonal precipitation was !!Q! statistically significant for the 1960-1974 time <br />period. However, there was a statistically significant difference for the 1975-1990 time <br />period between the control area and target area. Based on a comparison of average <br />control area and target area seasonal precipitation during the 1975-1990 time period. it <br />was concluded that the target area had 11 percent more precipitation than the control <br />area. <br /> <br />The results of this study should be interpreted with caution for three reasons. First, two <br />of the five control counties had cloud seeding operations occurring during portions of <br />both time periods used for analysis. Second, it appears that there may be errors in the <br />precipitation data listed in the Appendix of the study. For example, in 1960, the <br /> <br />5 Hun, Susan E. and Dr. William F. Simpson, Emporia State University, Analvsis of a <br />Cloud Seeding Program in Southwestern Kansas, 1975-1990, 18 pp. <br /> <br />7 <br />