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the effluent from the generator cools, literally trillions of microscopic sized particles of silver iodide are produced. These particles have the ability to cause water droplets within clouds that are colder than approximately _50C to freeze. The tiny ice crystal that is produced, if it remains in a favorable environment, will grow into a snowflake. NA WC will use a seeding solution composed of acetone, silver iodide, sodium iodide and paradichlorobenzene. This solution has been shown to produce more effective seeding particles at wanner temperatures (i.e. about _100 to _SoC and to produce these crystals more quickly than pure silver iodide (Finnegan, 1999). Other solution mixtures may be used in the future if research shows such solutions to be more effective. Each generator will consume 5-25 grams of silver iodide per hour of operation. Figure 1 provides locations of generators used during the 2006-2007 program. Some additional sites may be added to those depicted in Figure 1 for the continuation of this program. The project is planned to operate during the period of November 15th - April 15th during the next five winter seasons beginning in the 2007-2008 winter season. 4. Indicate How the Proposed Proiect is Desie.ned to Provide and Offers Promise of Providine Economic Benefit to the Tareet Area 4 The proposed project design is based upon NA WC's significant experience in designing, conducting and evaluating similar winter orographic weather modification projects in the western United States dating back to the 1950's. The design is also based upon the conduct of a number of research programs in weather modification including the Climax Experiments I and II conducted in the Central Rocky Mountains of Colorado ( Mielke, et ai, 1981) and the Colorado River Basin Pilot Project (CRBPP) conducted in the San Juan Mountains of south-western Colorado. NA WC' s former affiliate company, Aerometric Research, performed a comprehensive evaluation of the latter program (Elliott, et ai, 1976). Evaluations of previous NA WC winter orographic projects have indicated increases in target area precipitation in the range of 10-20%. For example, a long-term project that began in central and southern Utah in 1974 and continues to the present time has produced approximately a 14% increases in target area precipitation based upon a target and control evaluation (Griffith, et ai, 1991). NA WC has also conducted winter programs specifically for this target area under two separate permits from the Colorado Water conservation Board. These programs were conducted during the period from 2002 through 2007. Evaluations of the effectiveness of these programs for the three winters of 2003-2006 indicate an average 11 % increase in April 1 st snow water content in the primary target area's NRCS SNOTEL sites (Griffith, et aI, 2007). Based upon the positive results achieved in these projects, it is NA WC's expectation that a 10-20% increase in target area precipitation can be produced by the continuation of this program. The predicted 10-20% increases will have a variety of positive impacts within Gunnison County. The additional snow in the winter and spring months will benefit the tourism interests (i.e. skiing, snowmobiling). A report prepared by the Colorado Department of Natural Resources documents the impact of additional snow on ski area attendance (Sherretz and Loehr, 1983). This report estimated that a 15% in snowfall for hypothetical dry winters at Colorado ski areas are associated with 2-8% increases in total season visits. Increases in winter snowpack will result in enhanced spring and summer streamflow on the upper Gunnison River and its