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<br />research nature that do not have environmental impacts. All sites <br />proposed for installation of instruments are surveyed in advance, <br />usually in cooperation with a Federal land manager such as the Forest <br />Service. The stated Skywater policy is to avoid all sites of aesthetic, <br />archeological, or cultural significance and to avoid all sites at or <br />with which endangered or threatened animals or plants are identified. <br /> <br />Because many years of studies and field experience have shown the <br />environmental effects of the activities that will occur during the <br />initial phase of any of the proposed cloud seeding options are not <br />significant and are not adverse, a Finding of No Significant Impact will <br />be prepared for this phase. Work will be underway during the initial <br />phase to prepare the environmental compliance document and project <br />design required for the second phase of the program. Preparation of <br />these documents will includE~ design of the mitigating measures, moni- <br />toring systems, and suspensiQn critieria required for the Demonstration <br />Phase and operational activities. <br /> <br />2. The Demonstration Phase <br /> <br />Each of the three cloud seeding options includes a second, randomized <br />demonstration phase. The objectives of this phase are to produce <br />additional water in one or more subbasins, and to measure the amount of <br />the increase. Even though the number of seeding events will be tempered <br />because of the randomization feature, the water production objective is <br />similar to the goal of an operational mode. Experience indicates that <br />the effects of this type of demonstr:ation and/or an operational program <br />could include those covered in the following sections. <br /> <br />a. Impacts on Weather Elements. - The consensus of scientific <br />opinion is that a full-fledged operational winter cloud seeding <br />program in the Rocky MOUlntains of the Colorado River Basin could <br />result in a 10 to 15 pE:rcent precipitation increase. Such an <br />increase would be nested within a naturally high year-to-year 60 to <br />170 percent variation in precipitation over the long term [10J. <br /> <br />Studies of precipitation downwind from winter orographic cloud <br />seeding areas have shown increases at distances up to 250 kilometers. <br />Research does not indicate that seeding-produced increases in one <br />area deprive a downwind area of precipitation. The Colorado River <br />Basin Augmentation Demonstration design will provide for quantifi- <br />cation of extra-area/downwind precipitation effects due to seeding in <br />the primary project areas. <br /> <br />There is no reason to believe that cloud seeding would significantly <br />or adversely affect atmospheric humidity, existing variations in <br />cloudiness and sunshine, the length of the winter season, or the air <br />quality of the Basin. The potential for impacts on these elements <br />has been di scussed at 1 ength in both the Project Skywater Program- <br />matic Final Environmental Statement [2J and the Sierra Cooperative <br />Pilot Project Environmental Assessment [8J. Both documents concluded <br />that cloud seeding produced no effect on these weather elements, or <br />that the effect was not significant. <br /> <br />11 <br />