WSP02811

• File Number: 8200.766
• Description: Gunnison River General
• State: CO
• Basin: Gunnison
• Water Division: 4
• Date: 1/1/1991
• Author: USGS
• Title: Reconnaissance Investigation of Water Quality-Bottom Sediment-and Biota Associated with Irrigation Drainage - Gunnison and Uncompahgre River Basins and Sweitzer Lake - West Central Colorado
• Water Supply Pro - Doc Type: Report/Study

n02338

Stream discharge for the Uncompahgre River at Delta (gaging station
09149500 in fig. 1) during water year 1988 was affected by natural runoff
during winter and spring, irrigation diversions and return flows during
summer, and by the filling of Ridgway Reservoir. The annual stream discharge
for water year 1988 at gaging station 09149500 was only about 67 percent of
the average annual stream discharge for water years 1939-87. Compared to the
long-term stream-discharge record, stream discharge at gaging station 09149500
from October through mid-April was about normal, and stream discharge from May
through August generally was less than normal (fig. 6) in water year 1988.
During May, June, and July, the monthly mean stream discharges were less than
50 percent of the long-term average monthly mean stream discharges for cor-
responding months for water years 1939-87. Much of the decrease in stream
discharge in the Uncompahgre River at Delta during May through July 1988 can
be attributed to storage of water in Ridgway Reservoir.

Cl 1,100
Z
o
U
UJ
'"
a:
UJ
0-
f-
UJ
UJ
u..
u
1ii
:)
u
Z

1,000

900

WATER YEAR 1988

----- WATER YEARS 1939 THROUGH 1987

. WATER-QUALITY SAMPLE
COLLECTED AT SITE 9

800

700

.
"
I \~ \
, "
,\ I~ I,I~ "\
.. "~J '
r v' \
I I
, \
I \
~~\I \,
\/"''''....'\ ./
..j .....\}

-

800

500

,

.
1\

ui
'"
a:
<l:
I
U
'"
is
::;:
<l:
UJ
a:
f-
'"

400

300

200

100

o

NQV DEe JAN FEB MAR APR MAY JUNE JULY AUG SEPT

OCT

Figure 6.--Dai1y mean stream discharge for water year 1988, average daily
mean stream discharge for water years 1939-87, and dates when water-
quality samples were collected at streamflow gaging station 09149500,
Uncompahgre Rivet at Delta (site 9).

Although most of the data collection for the reconnaissance investigation
was done during a relatively dry year (water year 1988), the data collection
was at the end of an unusually wet hydrologic period in the Gunnison and
Uncompahgre River basins. Annual mean stream discharges in water years

J

15