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COLORADO WATER SUPPLY CONDITIONS UPDATE FROM THE OFFICE OF THE STATE ENGINEER; DIVISION OF WATER RESOURCES May, 1993 ROOM 818,1313 SHERMAN ST.,DENVER,CO 80203; (303)-866-3581 High snowpack statewide has resulted in high SWSI values. While percent of normal snowpack amounts had decreased during March, this trend reversed to show increases in all basins during April. Cool weather has delayed melting of both low and high elevation snow. High volumes of runnoff are forecast by the Soil Conservation Service, and flooding potential exists if the snow melt occures over a short period of time. Both this spring's SWSI values and the forecasted runoffs are the highest they have been since 1984. Stream flow forecasts statewide are for above average to much above average this spring and summer. The Soil Conservation Service reports statewide snowpack at 149% of normal for the end of April. The Gunnison basin had the highest amount at 166% of normal while the South Platte basin had the lowest amount at 132% of normal. Statewide reservoir storage was 104%of normal on April 30,with the Colorado basin having the highest storage rate at 116% of normal and the Arkansas basin having the lowest storage rate at 96%of normal. The National Weather Service 30 day forecast (May 1) is for below normal temperatures and above normal precipitation statewide. Their 90 day forecast(May 1) is also for below normal temperature and above normal precipitation over the entire state. Statewide precipitation was 97% of average during April. The Surface Water Supply Index (SWSI) developed by this office and the U.S.D.A. Soil Conservation Service is used as an indicator of water supply conditions in the major river basins of the state. It is based on snowpack,reservoir storage, and precipitation for the winter period (November through April). During the winter period snowpack is the primary component in all basins except the South Platte basin where reservoir storage is given the most weight. Inclusion of snowpack in winter computations results in an emphasis on present snow storage which may be available for next spring's runoff. The following SWSI values were computed for each of the seven basins on May 1, 1993 and reflect conditions during the month of April. May 1, 1993 Change From Change From Basin SWSI Value Previous Month Previous Year South Platte +2.0 +0.8 +1.1 Arkansas +2.2 +0.7 +3.6 Rio Grande +3.0 -0.2 +3.0 Gunnison +3.8 +0.1 +5.2 Colorado +3.3 +0.9 +5.7 Yampa/White +1.5 +1.6 +5.1 San Juan/Dolores +2.4 -0.5 +2.9 SCALE -4 -3 -2 -1 0 +1 +2 +3 +4 Severe Moderate Near Normal Above Normal Abundant Drought Drought Supply Supply Supply •