Glen Canyon Dam Operations
Releases from Glen Canyon Dam in January 2007 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 Mondays through Fridays 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 daylight and early evening on-peak hours). On Saturdays, release fluctuations will likely vary between a low of 9,000 cfs to a high of 16,000 cfs. On Sundays, release fluctuations will likely vary between a low of 9,000 cfs to a high of 15,500 cfs.
Releases from Glen Canyon Dam in February 2007 will be lower. A total of 605,000 acre-feet (an average of 10,900 cfs) are scheduled to be released in February 2007. Releases in March 2007 are scheduled to be 600,000 acre-feet for the month (an average of 9,800 cfs).
Upper Colorado River Basin Hydrology
Water year 2007 (which began on October 1, 2006) started out "wet,"
but shifted in November and December. October 2006 feature much above average precipitation and runoff. Precipitation in the Upper Colorado River Basin in October 2006 was over 200 percent of average.
Unfortunately, this trend did not continue for the remainder of the calendar year. Basinwide precipitation above Lake Powell in November and December was about 65 percent of average.
Inflow to Lake Powell increased dramatically in October in response to heavy precipitation. Unregulated inflow to Lake Powell in October 2006 was 184 percent of average and Lake Powell increased by 6.2 feet in elevation during the month. Inflow to Lake Powell returned to near average levels in November and December 2006. Unregulated inflow was 103 percent and 93 percent of average in these two months, respectively.
Basinwide snowpack above Lake Powell is currently 84 percent of normal (January 5, 2007). Forecasted April through July unregulated inflow to Lake Powell in 2007 is 7.2 million acre-feet, 91 percent of average. It is still early in the season, however, and this inflow projection could shift substantially depending upon climate patterns the remainder of this winter and spring.
The current elevation of Lake Powell (January 5, 2007) is 3,602.9 feet.
Reservoir storage is currently 12.03 million acre-feet, 49 percent of capacity.
The water surface elevation of Lake Powell is likely to decrease between now and April 2007 when anticipated snowmelt runoff will cause the water surface level to increase once more. The current projection for April 1, 2007 is 3,598 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 has been below average in all but one year (2005).
Water year 2007 (which began on October 1, 2006) got off to a good start with precipitation in the Colorado River Basin in October 2006 over 200 percent of average and Lake Powell increasing by 6.2 feet during the month. Unfortunately, this wet pattern was not sustained.
November and December were months with below average precipitation in the basin and the January projection for 2007 spring runoff into Lake Powell is below average (currently 91 percent of average). Storage in Lake Powell and Lake Mead remains relatively low, with reservoir storage currently 49 and 55 percent of capacity, respectively. The drought in the Colorado River Basin may not be over.
This release courtesy Tom Ryan, United States Bureau of Reclamation.