Glen Canyon Dam Update

Glen Canyon Dam Operations

Releases from Glen Canyon Dam in January 2008 will average 13,000 cubic feet per second (cfs) with a total of 800,000 acre-feet scheduled to be released for the month. On Mondays through Fridays in January, daily release fluctuations due to load following will likely vary between a low of 9,000 cfs (during late evening and early morning off-peak hours) to a high of 17,000 cfs (during daylight and early evening on-peak hours). On Saturdays and Sundays, release fluctuations will likely vary between a low of 9,000 cfs to a high of 16,500 cfs.

Releases in February 2008 are scheduled to be the lower than January 2008. A total of 600,000 acre-feet is scheduled to be released in February 2008 which is a daily average of 10,400 cfs.

In March 2008, a high flow test may be implemented. As a result of information resulting from scientific monitoring and research activities and stakeholder discussions in the Glen Canyon Dam Adaptive Management Program, Reclamation has proposed a 2008 high flow test. The dam release characteristics of such as test would be identical to the test conducted in November 2004 (with a maximum release of about 41,500 cfs for 60 hours), but under much more highly enriched fine sediment conditions, a unique situation during the last 10 years. This purpose of this test would be to determine the effectiveness of rebuilding and reworking sandbar deposits and backwaters in Marble and Grand Canyons. The Department of the Interior has concurred with (1) Reclamation's proposal to initiate environmental compliance activities on the proposed test, and (2) the United States Geological Survey's proposal to continue planning and scheduling scientific monitoring and research activities related to the test. The test is proposed to occur in early March; however, a final decision on whether to conduct such a test has not been made. Such a decision is currently expected to be made about mid-February 2008, only after environmental compliance actions are complete.  The annual release from Lake Powell for water year 2008 (currently projected to be 8.23 million acre-feet) would not change as a result of the high flow test.

Upper Colorado River Basin Hydrology

Precipitation in the Upper Colorado River Basin was 200 percent of average in December 2007. This made up for November 2007, a month which was almost devoid of storm systems. Basinwide snowpack was only 35 percent of average on November 29, 2007, but increased steadily in the month of December. January 2008, thus far, has continued the "wet" pattern seen in December. Basinwide snowpack above Lake Powell is currently 114 percent of average (January 8, 2008).

Inflow to Lake Powell is currently 8,000 cfs (January 7, 2008). Total unregulated inflow in October, November and December 2007 was 85, 73, and 92 percent of average, respectively.
Forecasted April through July unregulated inflow to Lake Powell in 2008 is 8.0 million acre-feet, 101 percent of average (January final forecast). This inflow projection could shift depending upon climate patterns the remainder of the winter and into the spring. Mid-January marks the half-way point in the snow accumulation season.

The current elevation of Lake Powell (January 8, 2008) is 3,593.6 feet, 106.4 feet from full pool elevation of 3,700 feet. Reservoir storage is currently 11.15 million acre-feet, or 46 percent of capacity. The water surface elevation of Lake Powell is now near its seasonal low. The water surface elevation of Lake Powell will likely decrease by about 4 feet between now and April. In April, anticipated snowmelt runoff will cause the water surface elevation to begin to increase. Under the current inflow forecast, Lake Powell would reach a peak elevation of about 3,628 feet in July 2008. The peak elevation for Lake Powell in 2007 was 3,611.7 feet.

Upper Colorado River Basin Drought

The Upper Colorado River Basin is experiencing a protracted multi-year drought. Since 1999, inflow to Lake Powell has been below average in every year except one.

In the summer of 1999, Lake Powell was essentially full with reservoir storage at
23.5 million acre-feet, or 97 percent of capacity. Inflow to Lake Powell in 1999 was 109 percent of average. The manifestation of drought conditions in the Upper Colorado River Basin began in the fall months of 1999. A five year period of extreme drought occurred in water years 2000, 2001, 2002, 2003, and 2004 with unregulated inflow to Lake Powell only 62, 59, 25, 51, and 49 percent of average, respectively. Lake Powell storage decreased through this five-year period, with reservoir storage reaching a low of 8.0 million acre-feet (33 percent of capacity) on April 8, 2005.

Drought conditions eased in water year 2005 in the Upper Colorado River Basin. Precipitation was above average in 2005 and unregulated inflow to Lake Powell was 105 percent of average. Lake Powell increased by 2.77 million acre-feet (31 feet in elevation) during water year 2005. But as is often the case, one favorable year does not necessarily end a protracted drought. In 2006, there was a return to drier conditions in the Colorado River Basin. Unregulated inflow to Lake Powell in water year 2006 was only 71 percent of average.

Water year 2007 was another year of below average inflow with unregulated inflow into Lake Powell at 68 percent of average. Over the past 8 years (2000 through 2007, inclusive), inflow to Lake Powell has been below average in all but one year (2005).
Reservoir storage in Lake Powell and Lake Mead has decreased during the past 8 years. Reservoir storage in Lake Powell is 46 percent of capacity. Storage in Lake Mead is 50 percent of capacity.

Courtesy of Tom Ryan, Bureau of Reclamation