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<br />Cloud seeding research activities in the Rocky Mountains, the Sierra Nevada, <br /> <br />the Medicine Bow Mountains, and the Cascades have been accomplished without <br /> <br />adverse environmental consequences. In addition, many Western States have <br />supported operational cloud seeding programs or have issued permits for <br />private sector programs. Certain environmental issues have been related to <br />winter orographic cloud seeding as a result of these research and operational <br />experiences. Some of these issues have been laid to rest by the scientific <br />community. Others wi 11 required cont inued data collect ion and monitoring in <br />order to judge their importance and impact. <br /> <br />An array of historical studies have concluded that incremental increases in <br /> <br />precipitation over the short terms of research mode cloud seeding programs do <br />not have significant adverse effects on various environmental-ecological <br />sectors. The primary reason cited for this conclusion is the fact that the <br /> <br />incremental increases are well within historic'\annua1 variations in precipi- <br />^ <br />tat ion in the study areas. As additional information and experience has <br />become available, estimates of long-term effects of precipitation augmenta- <br />tion have been moderated. The complexity of this analysis question was <br /> <br />recognized in 1977 by Howell: <br /> <br />lilt has come to be recognized that, in the settings so far inves- <br /> <br />tigated, the potential disturbing effect of weather modification <br /> <br />is overwhelmed by other disturbances to the status quo, some <br /> <br />manmade and some natural. <br /> <br />"From thi s state of affairs, two broad conc1 usions are now being <br /> <br />drawn. First, since investigation of the points of specific <br /> <br />environmental impact thought to have the highest potential for <br /> <br />16 <br />