Benefits from historic cloud seeding programs in California

California has the longest history of operational cloud seeding programs of any area in the world. The technology was first applied by the California Electric Power Company (now Southern California Edison Co.) beginning on February 2, 1948 over the Bishop Creek watershed in the eastern Sierra. Within the next few years additional programs evolved over watersheds of the San Joaquin, Kings, Mokelumne, and Feather Rivers. As the years evolved, additional programs were initiated over other areas of California as funded by county water agencies, municipalities and hydroelectric interests. During the 1994/95 winter season a total of 15 operational programs were active. Evaluations of several cloud seeding programs in California have been extensive. In addition to serious statistical methods applied to precipitation and streamflow data, these evaluations have more recently focused on extensive radar data collected by operational 3 cm and 5 cm weather radar systems. The combined benefits are explored from ten programs in California which have been active for various periods since 1950.