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J Also, the seeding is usually done during only part of a storm episode. For example, if a storm causes precipitation to fall over a six hour period, seeding may have occurred over only three of those hours. Therefore, over the period of a seeding program, seeding is likely to have occurred well under 100 percent of the time rain/snow was falling. The inability to isolate the snowfall that occurred when influenced by seeding, and compare this with historical snowfall that would have been seeded, causes us to use averages in our analysis which indicate increases which are likely less than what happens in individual seeding cases. Thus a "dilution" of the seeding effect occurs. In the Willow Creek Drainage, there are no sites which routinely gather precipitation data. There are, however, long-term sites which have gathered data on snowpack and water equivalent of snowpack. Therefore, we will concentrate our analysis efforts on the water content of the snowpack. 5.2 Evaluation of Snownack in the Tarl!:et Area The Soil Conservation Service (SCS) routinely measures the mountain snowpack once or twice a month, often starting in January and continuing until about June 1. Measurements were formerly made by visiting the site, taking a core sample of the snow, determining the depth of the snow and the water content. In more recent years (since about 1980) the advent of SCS's SNOTEL system has allowed frequent (daily) measurements of snow water content. With the use of a snowpillow, the water equivalent of the snowpack can be determined by remotely reading the weight of the snow on the snowpillow. The water content within the snowpack is important since it ultimately determines how much water will be available to replenish the underground and surface water 5-3