WSP08910

• File Number: 8282.600.40
• Description: Colorado River Annual Operating Reports
• Basin: Colorado Mainstem
• Date: 8/1/2000
• Author: USDOI/BOR
• Title: Colorado River Reservoir Operation Status Reports Part 2
• Water Supply Pro - Doc Type: Data

powerplant.

A public meeting on Navajo Reservoir operations will held on August 22, 2000 at I :00 pm in
Farmington, New Mexico. At this meeting, review of last spring and summer operations, and plans
for this fall 2000 operations will be discussed. These are open forum discussions on the operation of
Navajo Reservoir with many interested groups participating. Anyone interested in the general
operation of the reservoir is encouraged to attend. For further information about these meetings or
the daily operations of Navajo Reservoir please contact Ed Warner in Reclamation's Grand Junction
Office at [phone].

Glen Canyon Dam - Water year 2000 has been quite dry in the Upper Colorado River basin. April
through July unregulated inflow into Lake Powell was only 4.35 million acre-feet, 56 percent of the
long term average.

Water year 2000. began in a dry cycle, with basin precipitation first three months (October -
December, 1999) being only about 30 percent of average. January, February and March, however.
were months with above average precipitation. In early April. hydrologic conditions in the Colorado
River basin were approaching average, with basin snowpack at 90 percent of average, and forecasted
inflow to Lake Powell at 85 percent of average. Since April. it has been warmer and much drier than
normal, however. Precipitation in the Colorado River basin over the past 4 months has been only
about 50 percent of average. The result of this dry period has been less inflow into Lake Powell than
was forecasted in the spring.

The warm dry spring and summer has resulted in this years runoff being not only less than expected.
but earlier that expected as well. Unregulated inflow to Lake Powell in June and July was only 49
and 25 percent of average, respectively. Inflow is forecasted to be much below average for the
months of August and September as well. Under the current forecast, unregulated inflow to Lake
Powell in water year 2000 will be 7.7 million acre-feet (66 percent of average). The current
elevation of Lake Powell is 3681.6 feet (18.4 feet from full pool). Current storage is 21.5 million
acre-feet (88 percent of capacity). Inflow into Lake Powell is about 5,000 cfs.

Test releases from Glen Canyon Dam are now in progress. These test releases began in April and
will continue through the end of September. These test releases are for the benefit of endangered
humpback chub in the Grand Canyon and will assist in compliance with the Endangered Species Act.

Releases, as part of this test, were relatively high during April and May of 2000. From April 8
through the end of April, releases were 17.000 cfs. During May, releases were increased to power
plant capacity for 4 days (May 4-7). However, releases during most of May were in the 17.000 to
19,000 cfs range. Releases were reduced to 13,500 cfs the last 4 days of May. Releases from Glen
Canyon were at these relalively high levels during May to create ponding at the confluence between
the Little Colorado and Colorado Rivers. a condition considered to be
favorable for creation of a favorable spawning environment for humpback chubs.

Releases from Glen Canyon were reduced to 8,000 cfs on June 1,2000 and have remained at this
level since. Releases are scheduled to remain at this level for the remainder of August and most of
September. These low steady summer flows are an important component in this year's test releases