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('f, Silver iodide plumes released from foothill generators frequently had trajectories parallel to the mountain barrier rather than over it. Targeting was more successful downwind from higher elevation generators above 6600 ft. Extensive snow chemistry analysis was used to examine targeting effectiveness at 14 sampling sites within the intended target areas. A total of 1,68 I individual snow samples were collected for chemical analysis of silver concentration soon after seeding events. Less than 15 percent of the samples il".dicated any silver greater than back wound levels. In summarizing the silver sampling program, Reynolds et aI. (1989) concluded that, "These are disturbing results, even if one considers only scavenging, in that the Agl must not have passed over large regions of the target during precipitation events. Much of the AgI may be transported westward or northwestward at low levels, effectively not passing over the barrier." Finding evidence of seeding silver in less that 15 percent of such a large number of snow samples from long-term projects is beyond disturbing. It provides convincing physical evidence that the seeding programs were ineffective during the large majority of stonn passages, regardless of what any statistical analysis might suggest. Experience with numerous weather modification projects and experiments over the past 50 years has repeatedly shown that serious pitfalls are possible with statistical analyses not supported by solid physical evidence. But it is difficult to seriously argue with good physics. Similar poor targeting results were reported by Warburton et al. (1995a) for two large target areas in the Sierra Nevada. They showed that on average no more than 20 percent of the precipitation falling during seeding operations had seeding silver over several winters in the Truckee-Tahoe region. Silver concentrations were above threshold in 42 percent of the westerly wind seeded events in the Lake Almanor region, but only 8 percent with southerly flow, again showing lack of proper targeting in about 80 percent of all cases. Their "threshold" value, used to separate seeded from nonseeded snow, was shown to be about 4 parts per trillion (ppt) by weight. They concluded that, "It is considered reasonable to assume that when precipitation does not contain seeding silver above the 'threshold' value then there has been very little, if any impact by the seeding process." Snow samples were collected at various locations in Utah as part of an evaluation of a long- term operational program. Silver iodide seeding was done with valley generators except for a few locations with in-canyon generators. Analysis of silver-in-snow concentrations in the Tushar ~ountains and Sevier Plateau of southern Utah was reported by Long (1984). Only 11 of 145 snow ~ples (7.6 percent) had silver contents greater than background levels at the 5 percent Significance level, established at 11.6 ppt.. Indium oxide was also released as a tracer and only 2.8 percent of samples exceeded the 5 percent significance level; that is, fewer than expected by chance. These results indicate very poor targeting for the Tushar Mountains. Later snow sampling was reported for northern and central Utah by Super and Huggins (1992). Snow samples were collected in northern Utah after each stonn or series of stonns with sampling interVals ranging from a few to several days. Besides examining all northern Utah samples, an attempt was made to select only "well-seeded" samples, by reference to the operational seeding generator log and periods of snowboard exposure. But the frequency distribution of silver- in-snow concentrations from that attempt, as well as from all samples, both resembled the 10