Glen Canyon Dam Update

Glen Canyon Dam Operations

Releases from Glen Canyon Dam in February 2007 will average 10,900 cubic feet per second (cfs) with a total of 605,000 acre-feet scheduled to be released for the month. On Mondays through Fridays in February , daily release fluctuations due to load following will likely vary between a low of 8,500 cfs (during late evening and early morning off-peak hours) to a high of 14,500 cfs (during daylight and early evening on-peak hours). On Saturdays, release fluctuations will likely vary between a low of 8,500 cfs to a high of 14,000 cfs. On Sundays, release fluctuations will likely vary between a low of 8,500 cfs to a high of 13,000 cfs.

Releases from Glen Canyon Dam in March 2007 will be somewhat lower than February. A total of 600,000 acre-feet (an average of 9,800 cfs) are scheduled to be released in March 2007. Releases for April 2007 are also scheduled to be 600,000 acre-feet for the month (an average of 10,000 cfs).

Upper Colorado River Basin Hydrology

Limited precipitation reached the Upper Colorado River Basin in January 2007. Estimated basinwide precipitation in January is less than 50 percent of normal. While water year 2007 (which began on October 1, 2006) started out "wet," with October precipitation over 200 percent of average, precipitation in the Colorado River Basin since October has been below average. Basinwide snowpack above Lake Powell is currently 75 percent of average (as of February 2, 2007).

Forecasted April through July unregulated inflow to Lake Powell in 2007 is 5.9 million acre-feet, 74 percent of average. This is a 1.3 million acre-foot reduction from the forecast issued last month. This reduction reflects the limited amount of moisture received by the basin in January. It is still relatively early in the season, however. The current inflow projection could shift depending upon climate patterns the remainder of this winter and into the spring.

The current elevation of Lake Powell (February 2, 2007) is 3,599.4 feet, 100.6 feet from full pool elevation of 3,700 feet. Reservoir storage is currently 11.70 million acre-feet, or 48 percent of capacity. The water surface elevation of Lake Powell is likely to decrease between now and April 2007 when anticipated snowmelt runoff will cause the water surface level to increase once more. The current projection for April 1, 2007, is 3,596 feet.

Upper Colorado River Basin Drought

The Upper Colorado River Basin experienced five consecutive years of extreme drought from September 1999 through September 2004. In the summer of 1999, Lake Powell was essentially full with reservoir storage at 97 percent of capacity. Inflow volumes for five consecutive water years were significantly below average. Total unregulated inflow in water years 2000, 2001, 2002, 2003, and 2004 was 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.

Hydrologic conditions improved in water year 2005 in the Upper Colorado River Basin. Lake Powell increased by 2.77 million acre-feet (31 feet in elevation) during water year 2005. Unregulated inflow to Lake Powell in water year 2005 was 105 percent of average.

Unfortunately, in 2006, there was a return to drier conditions in the Colorado River Basin. Unregulated inflow to Lake Powell in water year 2006 was 73 percent of average. Over the past 7 years (2000 through 2006, inclusive) inflow to Lake Powell has been below average in all but one year (2005).

Water year 2007 (which began on October 1, 2006) is trending dry. October 2006 featured much above average precipitation, but in the months of November, December, and January, the basin has received below average precipitation. The current projection for spring runoff into Lake Powell is 74 percent of average. It is likely that inflow to Lake Powell will be below average once again in 2007. Storage in Lake Powell and Lake Mead remains relatively low, with reservoir storage currently 48 and 55 percent of capacity, respectively. The drought in the Colorado River Basin lingers on.

Environmental Impact Statement for Adoption of a Long-Term Experimental Plan for the Future Operation of Glen Canyon Dam

In a notice published in the Federal Register on November 6, 2006, the Bureau of Reclamation announced its intent to prepare an environmental impact statement (EIS) on the adoption of a Long-Term Experimental Plan for the future operation of Glen Canyon Dam and other associated management activities. The purpose of the Long-Term Experimental Plan is to increase understanding of the ecosystem downstream from Glen Canyon Dam and to improve and protect important downstream resources. The proposed plan would implement a structured, long-term program of experimentation (including dam operations, potential modifications to Glen Canyon Dam intake structures, and other potential management actions, such as removal of non-native fish species) in the Colorado River below Glen Canyon Dam.

For additional information about this EIS process, please visit our website at:

This release courtesy USBOR Tom Ryan