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COLORADO <br /> WATER SUPPLY CONDITIONS UPDATE <br /> FROM THE OFFICE OF THE STATE ENGINEER; DIVISION OF WATER RESOURCES May, 1991 <br /> ROOM 818,1313 SHERMAN ST.,DENVER,CO 80203; (303)-866-3581 <br /> JOHN R.KALISZEWSKI;EDITOR <br /> A series of snowstorms during the month of April contributed above normal snowfall to the central and northwestern <br /> regions increasing the statewide snowpack to 94%of average by May 1, 1991. This is 129% of last year's snowpack. The <br /> highest percentage was recorded in the Colorado basin at 107%of average. The South Platte basin,which has maintained <br /> the lowest snowpack of the major basins of the state throughout the winter, increased to 84% of average. Significant <br /> decreases in snowpack were realized in the upper Rio Grande, San Juan, Animas, Dolores, and San Miguel basins due to <br /> sublimation. The greatest decrease occurred in the Dolores basin dropping from 100% of average on April 1, 1991 to just <br /> 57% of average on May 1, 1991. Snowpack accounts for 80% of Colorado's annual water supply. <br /> Statewide precipitation for the month of April was 87%of average ranging from a low of 44%of average in the San <br /> Juan/Dolores basin to 126% of average in the Colorado basin. Totals for the water year (beginning October 1, 1990) are <br /> 104%of average. All basins are above average for the water year with the exception of the South Platte at 73%of average. <br /> The statewide reservoir storage is 115%of average, and 106%of last year's May 1st storage. The Colorado basin continues <br /> to have the lowest storage rates at 87% of average. Statewide storage is currently at 53% of capacity (approximately 9 <br /> million acre-feet). In the Colorado basin,diminished storage reflects to a degree early transbasin diversions supplementing <br /> below normal water supplies in the South Platte basin. The highest streamflow forecasts are in the Rio Grande basin. Below <br /> average streamflows are expected in the Yampa, White, Colorado, Gunnison, and South Platte basins. <br /> Ms. Suzanne Butterfield, Chief of the Division of Local Assistance within the California Department of Water <br /> Resources, addressing the Metropolitan Denver Water Authority,indicated that California will need to build more reservoirs, <br /> store excess runoff in ground water aquifers, and improve conservation practices. She stated that at current growth rates, <br /> available water supplies will likely be inadequate by the year 2000 even in non-drought periods. The costs of meeting these <br /> needs will be significant. State developed water is averaging $125 per acre-foot while alternative supplies, such as <br /> desalinized water, costs $1,800 per acre-foot. In Nevada, where less rain and snow falls than any other state, Las Vegas is <br /> running low on water. Officials want to lay as much as 1,000 miles of pipeline across the Nevada desert to extract water <br /> from a vast ground water aquifer beneath three rural counties. The Las Vegas Valley Water District filed 145 claims for <br /> unappropriated ground water totalling 864,195 acre-feet. Nevada has exhausted its share of Colorado River water(300,000 <br /> acre-feet). In Colorado,Aurora has decided to give up its plans to build the$400 million Collegiate Range water project in <br /> the Gunnison basin. Aurora was asked instead to come-up with a water policy that showed more cooperation with Western <br /> Slope interests. The National Park Service has outlined a plan to guarantee increased flows in the Gunnison River through <br /> the Black Canyon. The proposal asks that the U.S. Bureau of Reclamation increase releases from Blue Mesa Reservoir from <br /> 300 cfs to 1800 cfs during the summer months. <br /> The Surface Water Supply Index (SWSI) developed by this office is used as an indicator of water supply conditions <br /> in the state. It is based on reservoir storage, snowpack, and precipitation for the winter period (December 1st through May <br /> 1st). Weight factors are applied to each of the measured hydrologic factors in computing the SWSI values for each basin. <br /> During the winter period,snowpack is the primary component in each basin except the South Platte where reservoir storage <br /> is the primary component. The following SWSI values were computed for each of the seven basins on May 1, 1991: <br /> May 1, 1991 Change from <br /> Basin SWSI Value Previous Month <br /> South Platte -0.7 +0.2 <br /> Arkansas -0.6 +0.4 <br /> Rio Grande +1.3 -0.2 <br /> Gunnison . +1.4 +0.5 <br /> Colorado +0.3 +1.2 <br /> Yampa/White +0.6 +1.3 <br /> San Juan/Dolores -0.3 -0.2 <br /> SCALE <br /> -4 -3 -2 -1 0 +1 +2 +3 +4 <br /> Severe Moderate Near Normal Above Normal Abundant <br /> Drought Drought Supply Supply Supply <br /> 1 <br />