DWR_4151813

• Title: APRIL 1990 SWSI: COLORADO WATER SUPPLY CONDITIONS UPDATE, SURFACE WATER SUPPLY INDEX
• Year: 1990
• Document Type - Publications and Reports: SWSI Monthly Report

BASIN ASSESSMENTS
South Platte
The SWSI value of -0.5 is the highest of the seven major basins in
Colorado. The runoff forecast is 101% of average ranging from 58% for the
upper South Platte River basin to 125% for the upper Poudre River basin. Flow
for the month of March at the key index station, South Platte River near
Kersey, averaged 1311 cfs as compared to the normal flow of 659 cfs.
Throughout the Northern High Plains, the water levels continue to show the
regional decline which is to be expected when water is being "mined." There
are localized areas near the basin margins and in areas where water use has
been curtailed which show rising water levels. The data reflect the relative
change in water levels since 1989 and the overall change for the period of
1965 to 1989.
The average rate of decline for 1989 is slightly less than that for 1988
(0.93 feet in 1989 as compared with 1.06 feet in 1988) . Although the rate of
decline is less than the preceeding year, the rate exceeds the trend of the
middle 1980's. This appears to be the result of a continued dry cycle which
began about three years ago as well as the continued high price for crops.
Soil moisture is classified as being low.
Arkansas
The runoff forecast is 60% of average ranging from 58% for the Arkansas
River basin above Pueblo Reservoir to 78% for the Grape Creek basin. Winter
water storage in Pueblo Reservoir and John Martin Reservoir was 18,488
acre-feet behind the amount stored during this same period one year ago.
Pueblo Reservoir storage content was 150,653 acre-feet as of April 1, 1990, as
compared to 200,987 acre-feet in storage on April 1, 1989. Flow for the month
of March at the key index station, Arkansas River at Portland, averaged 272
cfs as compared to the normal flow of 273 cfs. Soil moisture is classified as
being low.
Rio Grande
The SWSI value of -2.8 is the second lowest in the state and indicates
moderate to severe drought conditions. Runoff is forecast to be only 45% of
average ranging from 28% for the San Antonio River basin to 76% for the
Culebra Creek drainage. Flow for the month of March at the key index station,
Rio Grande near Del Norte, averaged 212 cfs as compared to the normal flow of
273 cfs. Soil moisture is classified as being very low.
Gunnison
Runoff is forecast to be 45% of average ranging from 35% for the
Uncompaghre River basin to 61% for the upper Gunnison River basin. Flow for
the month of March at the key index station, Gunnison River at Delta, averaged
498 cfs as compared to the normal flow of 1989 cfs. Flows below Blue Mesa
Reservoir are significantly affected by storage releases which are highly
dependent upon hydroelectric power generation requirements. Soil moisture is
classified as being low to very low.