Glen Canyon Dam Operations
Releases from Glen Canyon Dam in October 2006 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 Fridays in October, daily release fluctuations due to load following will likely vary between a low of 6,500 cfs (during late evening and early morning off-peak hours) to a high of 12,500 cfs (during daylight and early evening on-peak hours). On Saturdays, release fluctuations will likely vary between a low of 6,500 cfs to a high of 12,000 cfs. On Sundays, release fluctuations will likely vary between a low of 6,500 cfs to a high of 11,500 cfs.
In November 2006, a total of 600,000 acre-feet are again scheduled to be released (an average of 10,000 cfs). The hourly release pattern for load following in November 2006 will likely be similar to October.
Upper Colorado River Basin Hydrology
Unregulated inflow to Lake Powell in water year 2006 (which ended on September 30, 2006) was 8.77 million acre-feet, 73 percent of average.
Water storage in Lake Powell is nearly identical to what it was a year ago. The elevation of Lake Powell today (October 3, 2006) is 3,601.6 feet. One year ago, the elevation of Lake Powell was 3,602.1 feet (about a half a foot higher than the current elevation). Reservoir storage is currently 11.9 million acre-feet, 49 percent of capacity.
Unregulated inflow to Lake Powell in September was 418,000 acre-feet, or 88 percent of average. Inflow is forecasted to remain in the 80 to 90 percent of average range for the remainder of calendar year 2006.
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 was a return to drier condition 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 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.