Glen Canyon Dam Operations
Releases from Glen Canyon Dam in September 2006 will average 9,000 cubic feet per second (cfs) with a total of 537,000 acre-feet scheduled to be released for the month. On Mondays through Fridays in September, 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 11,000 cfs (during daylight and early evening on-peak hours). On Saturdays and Sundays, release fluctuations will likely vary between a low of 6,000 cfs to a high of 10,500 cfs.
In October 2006, a total of 600,000 acre-feet are scheduled to be released (an average of 9,760 cfs).
Upper Colorado River Basin Hydrology
April through July unregulated inflow to Lake Powell was 5.32 maf, or 67 percent of the 30 year average. Unregulated inflow to Lake Powell has been below average since April 2006. Unregulated inflow in April, May, June, July and August was 103, 89, 53, 40, and 69 percent of average, respectively. Projected unregulated inflow to Lake Powell for water year 2006 is 8.73 maf, or 72 percent of average.
The water surface elevation of Lake Powell reached a seasonal low on April 7, 2006, at elevation 3,588.7 (111.3 feet from full pool). The water surface increased from April 7, 2006, until June 22, 2006, when Lake Powell reached a seasonal peak of 3,610.9 (89.1 feet from full pool). Since that time (June 22nd), the elevation of Lake Powell has been decreasing. The current (September 1, 2006) elevation of Lake Powell is 3,602.7 feet (97.3 feet from full pool). Current storage is 12.0 million acre-feet (49 percent of live capacity).
The water surface elevation of Lake Powell will likely continue to decrease through the fall and winter until April 2007, when anticipated snowmelt runoff will cause the water surface level to increase once more. The projected elevation of Lake Powell on January 1, 2007 is about 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 has been a return to drier condition in the Colorado River Basin. Inflow to Lake Powell will be below average in water year 2006. The current projection for inflow to Lake Powell in water year 2006 is 72 percent of average. Over the past 7 years (2000 through 2006, inclusive) inflow to Lake Powell will have been below average in all but one year (2005). While drought conditions eased in 2005, and the inflow in 2006 is not as extremely low as what occurred in 2000 through 2004, drought conditions in the Colorado River Basin persist.
The effects of multiple years of drought and low inflow remain visible at Lake Powell. Lake Powell storage is currently 49 percent of capacity with the water surface elevation nearly 100 feet below full pool.
This release courtesy Tom Ryan, Bureau of Reclamation.