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<br />industry is concerned that less snow from warming could seriously impact their operations, and <br />climate models indicate that the lowest-elevation Western resorts would be hurt first9. A recent <br />report10 declares that climate disruption in the West is already underway and will likely result in <br />more heat, less snoVvllack, and earlier snowmelt and runon: Other related impacts could include <br />more evaporation and droughts, less groundwater, and more llood-control releases. <br /> <br />There are several ways to ameliorate the looming crises by augmenting water supplies. One such <br />way is weather modification, commonly called cloud seeding. California is not alone in a recent <br />resurgence of interest in weather modification. On August 25, 2005, the seven Colorado River <br />Basin states addressed a letter 10 the Secretary of the Interior in ....'hich Ihey announced agreement <br />on the development of management strategies for operating Lakes Powell and Mead under low <br />reservoir (drought) conditions. The states said that they wish to work with the Department of the <br />Interior (Dol) to implement a cloud seeding program in the basin. TIle Metropolitan Water <br />District of Southern California (MWD) recently added their support for cloud seeding as one <br />way to augment llows in the river11. There are bills before the United States Ilouse of <br />Representatives (IIR-2995) and Senate (S-517). proposing a natiomvide weather modification <br />research program. Such a program was recommended by a National Research Council (NRC) <br />report on weather modilicalion research 11, a response to the NRC report by the Weather <br />Modification Association (WMA) lJ, and an article on the future of weather modification I';. The <br />Western States Water Council, which is accountable to the Western Governors' Association, <br />made a policy statement in July 2005 endorsing the national program and Congressional bills. <br />The remainder of this paper will discuss the state of weather modilicalion and its potential for <br />augmenting ..vater supplies in California and the West. <br /> <br />2. Contribution and limitations of Cloud Seeding Projects <br /> <br />Cloud seeding has been done in California for over 55 years. one of the longest records of <br />operational weather modification any\\'here in the world. The earliest program was at the Bishop <br />Creek watershed in the eastern Sierra in 1948, sponsored by the California Electric Pm\'er <br />Company. now Southern California Edison (SCE)15. The Lake AJmanor and Mokelumne <br />projects of Pacific Gas and Electric (PG&E)lb and Upper San Joaquin project of SeE have both <br />been run for over titly years. The Santa Barbara operational precipitation enhancement projectl? <br />began in 1950, \\lith some research phases between 1957-1960, and 1967-1974. Other programs <br />have been operated in Los Angeles and Monterey counties. <br /> <br />Most seeding in California has been intended to increase mountain snm....pack for greater <br />hydroelectric power gcncration. although some of the additional water has been targeted for Ihe <br />statc's huge urban and agricultural sectors. The projects have been principally located in the <br />Sierra Nevada and havc used ground-based silver iodide as the seeding agent in orographic <br />(mountain) clouds. In a few instances. liquid propane or hygroscopic materials were used for <br />secding. while aircratl seeding has been done under certain conditions1s. The number of <br />operating projects in California has tended to increase during droughts. up to 20 in 1991. but has <br />leveled olTto about 12 or 13 - see Figure 2 for a recent project map. <br /> <br />7 <br />