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COLORADO WATER SUPPLY CONDITIONS UPDATE FROM THE OFFICE OF THE STATE ENGINEER: COLORADO DIVISION OF WATER RESOURCES ROOM 818,1313 SHERMAN ST., DENVER, CO 80203 303-866-3581; www.water.state.co.us May 2004 The SWSI values rose in all basins compared to last month's values, a response to widespread above normal April precipitation. Snowpack, measured as a percent of average, increased during April in all basins except the Colorado and YampalWhite. In spite of that increase, the statewide May 1 snowpack is still only 68% of normal, and is below normal in all basins except the Rio Grande (which is 102% of normal). The low elevation snowpack is already gone in the Colorado and YampalWhite basins. In other areas of the state the April weather helped delay the spring snowmelt runoff. The runoff period is still expected to be earlier than normal statewide, and the spring through summer runoff forecasts are for flow below normal volumes of water. The Surface Water Supply Index (SWSI) developed by this office and the U.S.D.A. Natural Resources Conservation Service is used as an indicator of mountain-based 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. The following SWSI values were computed for each of the seven major basins for May 1, 2004, and reflect the conditions during the month of April. May 1, 2004 Change From Change From Basin SWSI Value Previous Month Previous Year South Platte +0.5 +2.2 +1.1 Arkansas -2.1 +1.2 -0.3 Rio Grande +0.8 +1.7 +4.0 Gunnison +0.5 +2.1 +2.2 Coiorado -2.1 +0.5 -2.5 YampalWhite -3.1 +0.2 -1.8 San Juan/Dolores +0.8 +1.3 +3.8 Scale -4 -3 -2 -1 0 1 2 3 4 Severe Moderate Near Normal Above Normal Abundant Drought Drought Supply Supply Supply