Join Date: Dec 2004
RRFW Riverwire Glen Canyon Dam Update
RRFW Riverwire Glen Canyon Dam Update
October 2, 2007
Glen Canyon Dam Operations
Releases from Glen Canyon Dam in October 2007 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 and Sundays, release fluctuations will likely vary between a low of 6,500 cfs to a high of 12,000 cfs.
Releases in November 2007 will likely be similar to October. The current schedule shows 600,000 acre-feet of release in November 2007, which corresponds to an average flow of 10,100 cfs.
Upper Colorado River Basin Hydrology
April through July unregulated inflow to Lake Powell in 2007 was 4.05 million acre-feet, only 51 percent of average. Water year inflow to Lake Powell for 2007 (October 2006 through September 2007) was 68 percent of average. The 2007 water year inflow was boosted by the heavy storm events that took place in October 2006 resulting in Lake Powell increasing by 6.2 feet during that particular month.
Inflow to Lake Powell is currently 9,600 cfs (October 1, 2007). Total inflow in September 2007 was 296,000 acre-feet, or 62 percent of average.
Powell reached a seasonal peak elevation of 3,611.7 feet on June 25, 2007. The current elevation of Lake Powell (October 1, 2007) is 3,601.9 feet with 11.93 million acre-feet of storage (49 percent of capacity). The elevation of Lake Powell is currently nearly identical to what it was one year ago today. [On October 1, 2006 the elevation of Lake Powell was 3601.7 feet]
The water surface elevation of Lake Powell will likely decrease between now and March of 2008. The projected elevation of Lake Powell on January 1, 2008 is 3,596 feet.
Upper Colorado River Basin Drought
The Upper Colorado River Basin is experiencing a protracted multi-year drought. Since 1999, inflow to Lake Powell has been below average in every year except one.
In the summer of 1999, Lake Powell was essentially full with reservoir storage at
23.5 million acre-feet, or 97 percent of capacity. Inflow to Lake Powell in 1999 was 109 percent of average. The manifestation of drought conditions in the Upper Colorado River Basin began in the fall months of 1999. A five year period of extreme drought occurred in water years 2000, 2001, 2002, 2003, and 2004 with unregulated inflow to Lake Powell only 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.
Drought conditions eased in water year 2005 in the Upper Colorado River Basin. Precipitation was above average in 2005 and unregulated inflow to Lake Powell was 105 percent of average. Lake Powell increased by 2.77 million acre-feet (31 feet in elevation) during water year 2005. But as is often the case, one favorable year does not necessarily end a protracted drought. In 2006, there was a return to drier conditions in the Colorado River Basin. Unregulated inflow to Lake Powell in water year 2006 was only 71 percent of average.
Water year 2007 was another year of below average inflow with unregulated inflow into Lake Powell at 68 percent of average. Over the past 8 years (2000 through 2007, inclusive), inflow to Lake Powell will have been below average in all but one year (2005).
Reservoir storage in Lake Powell and Lake Mead has decreased during the past 8 years. Reservoir storage in Lake Powell and Lake Mead is currently 49 and 48 percent of capacity, respectively.
This release courtesy Tom Ryan, US Bureau of Reclamation
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