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<br />effective operational program. The 3: I and 10: I ratios are dependent on spacing of the <br />seeding material generators. <br /> <br />During the 2003-2004 winter on the Wasatch Plateau; the Utah component of the WDMP <br />was conducted (Super and Heimbach, 2005). New chemical compositions, such as silver <br />chloride-iodide complexes, may act more efficiently to produce ice particles at <br />temperatures warmer than -5 degrees C, where AgI is ineffective. Similar warm <br />temperature results may be achieved by cost-effective liquid propane generators (Medina <br />2000). The Utah WDMP experiment operated such generators. AgI is thought to be <br />effective between -6 to -8 degrees C. Propane releases however can produce abundant <br />ice crystals as warm as -2 degrees C. This was one of the first attempts to test liquid <br />propane (LP) as a seeding agent in a fully randomized experiment. Targeting of the <br />seeded plume was assured from previous experiments. LP dispensers were remotely and <br />automatically operated, based on the presence of SL W measured at the dispenser site in <br />real time. A short-duration experimental unit (EU) elicited a robust population for <br />statistical analyses, of which there were three types. Seeded units produced over 20% <br />more snowfall than unseeded units. It was estimated that if all hours containing the EUs <br />had been operationally seeded, the seasonal (entire winter) precipitation increase would <br />have been 8%. The Utah WDMP experiment needs replication in other areas. <br /> <br />Nevada <br /> <br />Although Nevada is one of the seven Basin States, its snowpack enhancement activities <br />have been focused in northern Nevada in basins outside the Colorado River system. Its <br />research and operational programs are still applicable to the overall endeavors in <br />wintertime cloud seeding. Research in WxMod has been conducted through the Desert <br />Research Institute since the mid-1960s through both Bureau of Reclamation and NOAA <br />sponsored programs. Nevada actively participated in Project Skywater and the Sierra <br />Cooperative Pilot Project (Reclamation in 1970s and 1980s), the NOAA Atmospheric <br />Modification Project (1980s and 1990s) and the Reclamation Weather Damage <br />Modification Program (2003 to present). Two of the key areas of research have been use <br />of remote sensing to document seeding potential through the measurement of supercooled <br />liquid water, and the use of trace chemistry techniques to evaluate seeding effectiveness <br />(Warburton et al, 1995). In addition, a 3-year randomized cloud seeding experiment was <br />conducted in the 1970s (Pyramid Lake Project) to evaluate the effects of seeding in the <br />Lake Tahoe Basin. A statistical evaluation showed positive effects of seeding (-+17%) <br />in some storm partitions (stratifications), but the results were not significant at the 5 to <br />10% level. <br /> <br />Nevada has conducted a state-funded operational program since the 1970s, with <br />continuous operation over the past 21 years. The current program seeds five separate <br />drainage basins in northern Nevada and California (California basins drain into Nevada). <br />The project uses a combination of remotely-controlled ground generators and a single <br />seeding aircraft. Estimates of snowfall augmentation are based on periods of operation <br />and nominal precipitation increases during periods when all seeding criteria are satisfied. <br />The augmentation estimates have ranged from 50,000 to 80,000 acre-feet annually, which <br /> <br />-15- <br />