Glen Canyon Dam Operations
Releases from Glen Canyon Dam in January 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 weekdays 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 on-peak hours, which in winter months occurs in the mid-morning hours and again in the late afternoon and early evening hours). On Saturdays, releases will likely vary between a low of 9,000 cfs to a high of 16,000 cfs. On Sundays, releases will likely vary between a low of 9,000 cfs to a high of 15,500 cfs.
The release in February 2006 from Glen Canyon Dam is currently scheduled to be 800,000 acre-feet (an average release of about 14,400 cfs). Releases are currently scheduled to be reduced to 600,000 acre-feet in March 2006.
Upper Colorado River Basin Hydrology
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.
Hydrologic conditions improved in water year 2005 (October 2004 through September 2005) in the Upper Colorado River Basin. The elevation of Lake Powell increased by 31 feet during water year 2005 and storage in Lake Powell increased by 2.77 million acre-feet. Unregulated inflow to Lake Powell in water year 2005 was 105 percent of average.
On April 8, 2005, prior to the favorable snowmelt runoff of 2005, reservoir storage at Lake Powell reached a low of 3,555 feet (145 feet from full pool). The reservoir has declined to 33 percent of capacity,
and had not been that low since 1969. The current elevation of Lake Powell is 3,597.9 feet (102.1 feet from full pool). Current storage is 11.5 million acre-feet (47 percent of live capacity).
Thus far in water year 2006 (which began on October 1, 2005) inflow to Lake Powell has been close to average. Unregulated inflow in October and November of 2005 was 105 and 95 percent of average, respectively.
Unregulated inflow in December 2005 was 360,000 acre-feet, 82 percent of average.
Basinwide snowpack in the Upper Colorado River Basin is currently 109 percent of average (as of January 4, 2006). Precipitation in the basin since October 1, 2005 has been about 115 percent of average. The distribution of snow in the basin varies greatly by geographical location. Snowpack in the upper San Juan River basin, for instance, is only 35 percent of average, while snowpack in the Yampa and Colorado
River headwaters is about 140 percent of average.
Forecasted April through July unregulated inflow to Lake Powell in 2006 is 8.5 million acre-feet, 107 percent of average.
The water surface elevation of Lake Powell is likely to decrease until late March or early April 2006 when anticipated snowmelt runoff will cause the water surface level to increase once more. The current projection the water surface elevation at Lake Powell on April 1, 2006, is about 3,592 feet.
This release courtesy Tom Ryan, U.S. Bureau of Reclamation