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Precipitation variables would be examined in areas outside the primary target including some gauges further downwind, both at valley locations and in the next mountain ranges in the northeast through southeast quadrant. The possibility of downwind effects (precipitation changes downwind of the intended target) due to seeding has been raised many times, but finn evidence for such effects is lacking. While most statistical suggestions indicate increased snowfall for some distance downwind of target areas, further investigation of downwind effects is warrant,:d. 7.4 Demonstration Program Cost and Other Options The costs of a demonstration program have not been estimated specifically for the Sevier River. Similar estimates were recently prepared for a proposed 5-year program for Arizona and 7-year program in Montana. Both estimates had an average annual cost of approximately $2.0 million, assuming 4- to 5-month field seasons. Such costs are well in excess of the current costs of the Utah operational program. It is likely that only State and Federal Governments or very large users organizations could afford the sort of demonstration program that is needed to validate the technology of winter orographic cloud seeding. Additional costs would be required to comply with State and Federal environmental assessments. A discussion of environmental assessment and monitoring requirements is beyond the scope of this report, but compliance with these requirements obviously would be necessary. The program that has been proposed is considered to be the best means of demonstrating a validated technology in less than a decade. However, it should be pointed out that other options certainly exist that are less costly on an annual basis. One option always is to do nothing. In this case the likely result would be continuation of operational seeding as previously conducted for modest cost. The major risk of that approach is that the program's effectiveness will continue to be unknown. However, in view of the expense of reducing uncertainties about seeding effectiveness, water users could decide to continue to accept the risks involved with operational seeding; that is, they could continue to assume that seeding was producing water worth more than their costs. In reality, the Utah DWR has been following a much better option than "doing nothing" for over a decade in southern and central Utah. The Utah/NOAA Atmospheric Modification Program has been pursuing research into winter cloud systems and their modification as earlier reviewed. This work is ongoing on the Wasatch Plateau, located in the northeast comer of the Sevier River Basin, so it has direct relevance to the basin. An improved understanding of clouds and their modification potential has resulted, especially concerning the availability of SLW. The Atmospheric Modification Program has recently turned its major focus toward delivery of adequate concentrations of effective ice nuclei to SL W cloud regions. Other major questions that have been identified by the Utah/NOAA program, but not yet thoroughly investigated, concern the physical processes responsible for precipitation development and the trajectories followed by seeded ice crystals. The Utah/NOAA program funding, currently about $0.5 million per year, has restricted field programs to 6 to 8 weeks every other winter, and these programs have been able to address only one or two key questions at a time. This approach has the advantage of less annual cost than the more comprehensive program discussed in following sections. However, the current approach will require considerably longer to validate winter cloud seeding technology. Moreover, even if all key physical processes are verified, it will be difficult or impossible to accurately estimate the seasonal water increases produced by seeding without conducting a randomized statistical experiment with a strong physical emphasis. That will require funding well in excess of present levels. 55