DWR_4151786 - Laserfiche WebLink

f t COLORADO ` WATER SUPPLY CONDITIONS UPDATE 1 FROM THE OFFICE OF THE STATE ENGINEER; DWISION OF WATER RESOURCES December, 1991 ROOM 818,1313 SHERMAN ST.,DENVER,CO 80203; (303)-866-3581 A shift in the major SWSI component from stream flow (summer component) to snowpack (winter component) and heavy snow storms statewide during the month of November caused large increases in the computed SWSI values in all basins except the South Platte compared to last months values. Statewide reservoir storage was 107% of average on December 1. The San Juan/Dolores/Animas basin has'the highest storage rate at 136% of average while the Rio Grande basin has the lowest storage rate at 93% of average. The National Weather Service 30 day forecast(December 1)for Colorado is for above normal precipitation and below normal temperatures. The 90 day forecast (December 1) is also for above normal precipitation and below normal temperatures statewide. The Surface Water Supply Index (SWSI) developed by this office 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 1st through April 30). 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 the presant snow storage for next spring's runoff. The following SWSI values were computed for each of the seven basins on December 1 , 1991: December 1, 1991 Change From Change From Basin SWSI Value Previous Month Previous Year South Platte +1.2 -0.7 +2.1 Arkansas +3.1 +3.5 +1.7 Rio Grande +2.8 +3.8 +2.9 Gunnison +3.1 +4.5 +2.3 Colorado +2.3 +3.0 +3.0 Yampa/White +2.7 +4.9 +2.3 San Juan/Dolores +3.0 +4.5 +2.3 SCALE -4 -3 -2 -1 0 +1 +2 +3 +4 Severe Moderate Near Normal Above Normal Abundant Drought Drought Supply Supply Supply 1