WSP10807

• File Number: 8210.137
• Description: Colorado River Basin-Colorado River Basin Organizations/Entities-Colorado River Forecast Committee
• Date: 2/1/1984
• Author: USDA, USDC, NOAA,NWS
• Title: Water Supply Outlook for the Western United States
• Water Supply Pro - Doc Type: Report/Study

COLUMBIA BASIN -- Continued

Reservoir storage for the
excellent. with all states
February 1 reservoir levels.

a whole Is
above-normal

basin 8a
reporting

GREAT BASIN

The water supply outlook for the spring runoff Is much
above normal over most of the Great Basin. A dry January
helped to decrease volume forecasts 25 to 28 percent over
those issued on January 1. Streamflow is still expected
to be much above normal over much of the basin.

PrecipitatoR during January was generally less than 50
percent over Utah except along the eastern border and a
few isolated aress along the Wasatch Range where amounts
were 50 to 80 percent of average. January precipitation
averaged 30 percent of normal in Nevada.

Seasonal precipitation remains much above normal, 150
to 200 percent over north and central Utah decreasing
to near normal over the extreme southern areas of Utah.

Snowfall during January was much below normal
throughout the basin. February 1 snow surveys indicate a
decline of 50 to 70 percent from average in the basin
snowpacks from the January 1 readings. Even though
little precipitation was received. the snowpack remains
much above normal due to the heavy snowfall which
occurred earlier.

Observed streamflow continues much above normal
sveraging 146 percent at the seven index stations the
Geological Survey measures throughout Utsh. The combined
contents of 23 reservoirs in Utsh is 3.6 milion
acre-feet, 138 percent of average and 89 percent of
capacity. This is almost identical to the amount of
water stored last year at this time. However, some
additional storage space has been made available on the
Weber and Odgen drainages this year.

The elevation of the Great Salt Lake on February 1
was 4,206.3 feet above KSL. This is 4.4 feet higher than
last year at this time and is expected to peak at 4,208
to 4.209 feet HSL early this summer. Utah Lake is at the
same level it waa on January 1, 3.36 feet above
compromise and is expected to rise to 5 to 6 feet above
compromise early this spring. Pyramid Lake has risen 4.2
feet since October 1983 and is expected to rise another
4.23 feet this summer.

Although the dry weather pattern in January has helped
to ease the threat of spring flooding, forecasts are
still high enough so that some flooding problems are
still likely. With valley snow remaining on the ground,
any combination of a winter thaw and rains are likely to
create some pooling of water in poor drainage areas for
the next several months. Residents should be alert to
westher situations which could cause possible basement
flooding and take the necessary precautions.

With high ground water tables and above normal aurface
runoff expected this spring the threat of mud slides is
still very real and those areas susceptible should be
watched carefully.

COLORADO BASIN

Forecasts above Lake Powell dropped lU to 25 percent
from those issued on January 1 as a result of the dry
weather pattern during January. However, the water
supply outlook is for above normal streamflow forecasts
in the Upper Colorado River drainage. Forecasts of
apring runoff on the Lower Colorado River Baain are much
below normal in central Arizona. The lower forecast
volumes on the Colorado River have eased the threat of
spring snowmelt flooding. However, the threat of snowmelt
flooding is still of concern this spring.

Precipitation dueing January was generally 25 to 50
percent of average throughout most of the headwater areas
in Colorado and Utah. Over central Arizona. January
precipitation was less than 50 percent of normal.

Seasonsl precipitation- October through January ranges
from near normal in portions of the San Juan Basin and
central Arizona to greater than 15U percent in
northwestern Colorado and southwestern Wyoming.

Snoll/fall was much below normal during January and
helped to push the snoll/pack. closer to normal. but some
areas are still experiencing record snow water
equivalents. Tloienty-four of the 130 snow courses
measured in western Colorado either set or tied the
maximum of record for the 1st of February. The snowpack
on the Arizona Watershed ranges from Blj percent on the
Gila to 40 percent on the Verde.

January streamflow diminished on the San Juan
River but continued above norlll81 on the Colorado main
stem. The Green River Basin is still the big producer
with record inflows to Fontenelle and Flaming Gorge
Reservoir and a new record flow at Green River. Utah.
Inflow to Lake Powell during January waa the highest
January flow on record. Since October 1 the total inflow
to Lake Powell has been 2.5 million acre-feet, 160
percent of average.

Reservoir storage remains high with the combined
storage of ten majo~ reservoirs above Lake Powell of 6.6
million acre-feet, 82 percent of capacity, 141 percent of
average and nearly the same storage as last year at thia
time. Storage in Lake Powell is 22.0 million acre-feet,
88 percent of capacity, and about 400.000 acre-feet lower
than last year at this time. The April-July inf low
forecast to Lake Powell is 12.4 million acre-feet. 166
percent of the 20-year 1961-l9ljO average.

RIO GRANDE BASIN

The Rio Grande water supply outlook for the 1984 season
is for above normal runoff for all the basin. Runoff
amounts are expected to range from 120 to l4U percent of
average in the Colorado portion of the basin and 110 to
175 percent of average in New Hexico.

January precipitation totals were below normal over
most of the basin ranging from 3U to 70 percent in
Colorado and 10 to 80 percent in New Hexico. Seasonal
precipitation totala in the basiu now average 7U to 150
percent percent in Colorado and /)0 to 170 percent of
average in New Mexico. In the Pecos Baain from Sumner
Lake south to Roswell amounts are around twice the
20-year average.

The baain snowpack. is currently 137 percent of
average, down nearly 50 percent from January 1 figures.
This decrease from normal is attributed to the below
normal anowfall in January. Because of the heavy
snowfall in December, the baa in snowpack. ia still l4U
percent higher than the amount observed last year at this
time.

Reservoir storage continues well above average at all
area lakes. Volumes in storage are now 166 percent of
average in the basin in Colorado and 237 percent of
average in New Mexico. At Elephant Butte and Caballo
Reservoirs there is 1.5 million acre-feet in storage.
which is about a 45 percent increase over last year at
this time.

ARKANSAS BASIN

The water supply outlook for the Arkansas River Basin
calls for runoff amounts above average over all the
baain. Along the main stem, runoff volumes are expected
to be 145 to 170 percent of average. Further south along
the tributaries, amounts will range from 125 to 150
per~ent of average.

Precipitation received during the month of January was
below normal over all but that portion of the basin east
of Colorado Springs to La Junta, where totals up to 150
percent of average were recorded. The remainder of the
basin ranged from a trace to 70 percent of average.
October through January seaaonal totals now range from
slightly below average to near 150 percent of average in
that portion of the basin above Pueblo and from 50
percent to near average below Pueblo.

2

Hountain snowpack in the baain continues well above
....continued on pa~e 6