DWR_4151782

• Title: FEBRUARY 1992 SWSI: COLORADO WATER SUPPLY CONDITIONS UPDATE, SURFACE WATER SUPPLY INDEX
• Year: 1992
• Document Type - Publications and Reports: SWSI Monthly Report

•
COLORADO
WATER SUPPLY CONDITIONS UPDATE
FROM THE OFFICE OF THE STATE ENGINEER; DIVISION OF WATER RESOURCES February, 1992
ROOM 818,1313 SHERMAN ST.,DENVER,CO 80203; (303)-866-3581
A winter time 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 SWSI values
computed during early winter. A dry December and January have lowered the SWSI components significantly.
Statewide reservoir storage was 103%of average on February 1. The San Juan/Dolores/Animas basin has the highest
storage rate at 134% of average while the Arkansas basin has the lowest storage rate at 82% of average.
Statewide snowpack was 87% of average on February 1. Snowpack varied widely within a few of the major river
basin. The Arkansas River basin has the highest rate at between 89%and 141% of average while the northwestern portion
of the state in the Yampa/White River basins had the lowest rate at 76% of average.
The National Weather Service 30 day forecast(February 1) for Colorado is for above normal precipitation and below
normal temperatures. The 90 day forecast (February 1) is for above normal precipitation and below normal temperatures
for all but the northwest corner of the state, where near normal precipitation and temperatures are forecast.
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 the present snow storage for next spring's runoff. The following
SWSI values were computed for each of the seven basins on February 1 , 1992:
February 1, 1992 Change From Change From
Basin SWSI Value Previous Month Previous Year
South Platte -0.1 -0.6 -0.5
Arkansas -0.1 -2.2 +0.8
Rio Grande +0.2 -1.6 -0.7
Gunnison -1.3 -2.6 -1.1
Colorado -1.8 -1.9 -0.2
Yampa/White -2.4 -1.4 -1.3
San Juan/Dolores -0.5 -2.1 -0.2
SCALE
-4 -3 -2 -1 0 +1 +2 +3 +4
Severe Moderate Near Normal Above Normal Abundant
Drought Drought Supply Supply Supply
1