WMOD00295 - Laserfiche WebLink

Home Browse Search

ASPECTS OF PRECIPITATION IENHANCEMENT 19 partment of Water Resources, overdraft of aquifers can be 2.5 million acre-foot 6/year; this can lower the ground water level by several hun- dred feet, making it cost-prohibitive to pump, subsequently causing land subsidence and introducing water quality problems. New considerations are being given to water augmentation and reuse programs; indeed, Arizona public policy, driven by economic and environmental considera- tions, officially acknowledges cloud seeding as a possible water augmen- tation method (Reinking 1992; Gelt 1992). The Salt River and Verde River watersheds contribute one million acre-foot/year; here alone, a 15% in- crease in runoff would meet the needs of 750,000 persons annually. For Nevada, the Desert Research Institute indicates that the 1990 valu- ation of urban water rights is about $2500/acre-foot, and runoff yields from precipitation enhancement at 0.025 cm/hr for normal hours of precipitation would cost about $1O/acre-foot. 2.2.2.2 Utah. Utah is the$econd driest state. The winter snowpack and associated runoff are necessary for agricultural and urban supplies and for the ski industry. The state spends some $8.5 million annually (1990 valuation) on water development, according to the Utah Division of Water Resources (UDWR)(Sup~r and Reynolds 1991). Demands for ur- ban use will increase with the state's population, which is projected to increase by one-third by 2005. As in other states, early season snowfall is highly valued by the ski industry. The agricultural need is for late-season irrigation water which is valued near $40/acre-foot, according to the UDWR, whereas the estimated direct cost of water from an 8-12% in- crease in snowpack from cloud seeding in key mountain watersheds is $1O/acre-foot. In 1989-1990, 17 counties contributed nearly $0.5 million to cost-share operational cloud seeding with the State. This level of cost- sharing has continued, and has been consid,ered as a reasonable benefit- cost risk, even though the State has continued to collaborate with the federal government in research to determine the actual efficacy of cloud seeding (Reinking and Meitin 1989; Reinking 1992). Benefit-cost ratios of 3:1 to 10:1 were estimated for 10% mountain snowfall increases in the Sevier River basin in Utah (Super and Reynolds 1991). The basis was the amount of additional water potentially pro- duced, the estimated value of the additional stream flow, and the direct cost of conducting an effective operational program. Not accounted for were other benefits and costs that would afflect an aggregate benefit-cost ratio. The 10:1 ratio reflects costs of the Utah operational seeding pro- gram as currently conducted, using widely spaced valley generators. The 3:1 ratio reflects the additional costs of using closely spaced, high output generators well up the windward slopes to improve targeting. The Na- 6acre-foot = 1.23335 X 1()3 m3. Acre-foot, where used in this document, is quoted in the referenced sources, and may be most useful to the intended audi- ence.