Glen Canyon Dam Update

Glen Canyon Dam Operations

Releases from Glen Canyon Dam in March will average 9,800 cubic feet per second (cfs) with a total of 600,000 acre-feet scheduled to be released for the month.  On Mondays through Sundays in March, daily release fluctuations due to load following will likely vary between a low of 6,000 cfs (during late evening and early morning off-peak hours) to a high of 12,000 cfs (during on-peak hours, which in March occurs in the mid-morning hours and again in the late afternoon and early evening hours).

The release volume from Glen Canyon Dam is currently scheduled to be 600,000 acre-feet in both April and May of 2006.

Upper Colorado River Basin Hydrology

February 2006 was a dry month in the Colorado River Basin.  As February began, basinwide snowpack above Lake Powell was above average.   As the month progressed, however, snowpack dropped below average with a total decrease of 15 percentage points during the month.   Precipitation in the Upper Colorado River Basin during February was approximately 50 percent of average.  Basinwide snowpack (as of March 2, 2006) is currently 93 percent of average.  The distribution of snow in the basin varies greatly by geographical location.  Snowpack in the San Juan River Basin, for instance, is only 40 percent of average, while snowpack in the Yampa and Colorado River headwaters is about 115 to 120 percent of average.  

Inflow to Lake Powell in water year 2006 (which began on October 1, 2005) has been near average, although it dropped off somewhat in February.

Unregulated inflow from October 2005 through February 2006 was 94 percent of average.  However, unregulated inflow in February 2006 was only 79 percent of average. 

In response to the minimal amount of precipitation in February, the National Weather Service has reduced the inflow forecast for Lake Powell this spring.   The current forecasted April through July unregulated inflow to Lake Powell for 2006 is 7.2 million acre-feet, 91 percent of average.

The current elevation of Lake Powell is 3,589.7 feet (110.3 feet from full pool).  Current storage is 10.8 million acre-feet (44 percent of live capacity).

The water surface elevation of Lake Powell is now near its seasonal low.

The water surface elevation is likely to remain near elevation 3,590 feet during March 2006 and then begin to increase in April 2006, when anticipated snowmelt runoff will cause inflow to exceed the level of release.  The current projected high elevation of Lake Powell in 2006 is about 3,620 feet (80 feet from full pool), occurring in mid-July. 

The actual high elevation could deviate significantly from this projection however.  Weather patterns from now through the end of spring will influence the volume of inflow to Lake Powell during this year's April through July snowmelt runoff season.

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 drought, with reservoir storage reaching a low of 8.0 maf

(33 percent of capacity) in early April of 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. 

The effects of the drought remain visible at Lake Powell where reservoir storage has been reduced.  Lake Powell storage is currently only 44 percent of capacity.

This release courtesy Tom Ryan, U.S. Bureau of Reclamation