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e e Pilot Project Environmental Assessment [8J, and are also covered by Departmental and WPRS Instructions providing for categorical exclusions for data collection and other activities of a research nature that do not have environmental impacts. All sites proposed for installation of instruments are surveyed in advance, usually in cooperation with a Federal land manager such as the Forest Service. The stated Skywater policy is to avoid all sites of aesthetic, archeological, or cultural significance and to avoid all sites at or with which endangered or threatened animals or plants are identified. Because many years of studies and field experience have shown the environ- mental effects of the activities that will occur during the initial phase of any of the proposed cloud seeding options are not significant and are not adverse, a Finding of No Significant Impact will be prepared for this phase. Work will be underway during the initial phase to prepare the environmental compliance document and project design required for the second phase of the program. Preparation of these documents will include design of the mitigating measures, monitoring systems, and suspension criteria required for the Demonstration Phase and operational activities. 2. The Demonstration Phase Each of the three cloud seeding options includes a second, randomized demonstration phase. The objectives of this phase are to produce addi- tional water in one or more subbasins, and to measure the amount of the increase. Even though the number of seeding events will be tempered becavse of the randomization feature, the water production objective is similar to the goal of an operational mode. Experience indicates that the effects of this type of demonstration andlor an operational program could include those covered in the following sections. a. Impacts on Weather Elements The consensus of scientific opinion is that a full-fledged operational winter cloud seeding program in the Rocky Mountains of the Colorado River Basin could result in a 10 to 15 percent precipitation increase. Such an increase would be nested within a naturally high year-to-year 60 to 170 percent variation in precipitation over the long term [10J. Studies of precipitation downwind from winter orographic cloud seeding areas have shown increases at distances up to 250 km. Research does not indicate that seeding-produced increases in one area deprive a downwind area of precipitation. The Colorado River Basin Augmentation Demonstration design will provide for quantification of extra-areal downwind precipitation effects due to seeding in the primary project areas. There is no reason to believe that cloud seedinq would significantly or aaversely affect atmospheric humidity, existina variations in clOUDiness ana sunsnlne, tne lenqth OT tne wInter season, or (he aIr QualIty or the Basin. The potential for impacts on these elements has been aiscussed at length in both the Project Skywater Programmatic Final 11