Glen Canyon Dam Update

Glen Canyon Dam Operations

Releases from Glen Canyon Dam in April 2006 will average 10,000 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 April, daily release fluctuations due to load following will likely vary between a low of 6,250 cfs (during late evening and early morning off-peak hours) to a high of 12,250 cfs (during daylight and early evening on-peak hours).

The release volume from Glen Canyon Dam is currently scheduled to be 600,000 acre-feet in May 2006. June 2006 releases are currently scheduled to be 800,000 acre-feet.

Upper Colorado River Basin Hydrology

March 2006 featured cooler than average temperatures in the Upper Colorado River Basin. Precipitation was moderately above average for the month. This pattern helped boost snowpack in the Upper Colorado River Basin. As March began, basinwide snowpack above Lake Powell was below average (93 percent of average on March 1, 2006), but increased throughout the month. Precipitation in the Upper Colorado River Basin during March was approximately 130 percent of average. Basinwide snowpack (as of April 4, 2006) is currently 103 percent of average. The distribution of snow in the basin continues to vary by geographical location although this variability was reduced somewhat in March when the southern regions of the basin finally experienced a few significant storm systems. The northern regions continue to fare better than regions in the south. Snowpack in the San Juan River Basin, for instance, is only 65 percent of average, while snowpack in the Duchesne, 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) thus far has been about 88 percent of average. Inflow, as a percentage of average, has dropped somewhat the past two months, however. Unregulated inflow in February 2006 was 79 percent of average.

 Unregulated inflow in March 2006 was 448,100 acre-feet, only 68 percent of average. The low March inflow was a function of cooler than average temperatures during the month.

The National Weather Service issued the April final inflow forecast on April 4, 2006. Forecasted April through July unregulated inflow to Lake Powell for 2006 is 7.7 million acre-feet, 97 percent of average.

The current (April 4, 2006) elevation of Lake Powell is 3,588.7 feet (111.3 feet from full pool). Current storage is 10.7 million acre-feet (44 percent of live capacity).

The water surface elevation of Lake Powell is now at its seasonal low. The water surface elevation will increase during April, May, and June, and probably in early July as well. The current projected high elevation of Lake Powell in 2006 is about 3,625 feet (75 feet from full pool), occurring in mid-July. The actual high elevation could deviate 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) 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.

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