Releases from Glen Canyon Dam in August will be very similar to July. A total of 893,000 acre-feet will be released from Glen Canyon Dam during August 2002. On Mondays through Fridays in August, daily fluctuations due to load following will likely vary between a low of about 10,000 cfs (during late evening and early morning off-peak hours) to a high of about 18,000 cfs (during late afternoon and early evening on-peak hours). On Saturdays during this period, releases will likely vary between a low of about 10,000 cfs during off-peak hours, to a high of about 16,500 cfs during on-peak hours. On Sundays, releases will likely vary between a low of about 10,000 cfs during off-peak hours to a high of about 15,000 cfs during on-peak hours.
September releases will be much lower than August. Total releases in September, 2002 will be 480,000 acre-feet, which averages out to 8,000 cfs.
Water year 2002 continues to be an extremely dry year in the Colorado River Basin. The April through July unregulated inflow to Lake Powell during 2002 was only 1.11 million acre-feet. This is only 14 percent of average. This is the lowest unregulated inflow ever recorded since the completion of Glen Canyon Dam. The previous low occurred in 1977, when April through July inflow to Lake Powell was only 1.28 million acre-feet.
Basinwide precipitation continues to be below normal into the summer months of 2002 and inflow is expected to be significantly below normal through the remainder of the summer and into the fall. Observed inflow into Lake Powell is currently 2,500 cfs (August 6, 2002). The historic average inflow into Lake Powell in early August is about 12,000 cfs.
Drier than average conditions have now prevailed for the past three years in the Colorado River basin. Both water years 2000 and 2001 were below average inflow years. Total unregulated inflow into Lake Powell in water year 2000 was 62 percent of average, while water year 2001 registered inflow at 59 percent of average.
On April 24, 2002, members of the Glen Canyon Adaptive Management Work Group (AMWG) recommended to the Secretary of the Interior that experimental flow tests be made from Glen Canyon Dam beginning in water year 2003. The recommendation addressed the decline of two key resources in the Grand Canyon, sediment and population viability of endangered humpback chub. More information on the recommended experimental flows can be found at www.uc.usbr.gov/pao/exp_flows_glencanyondam.html.
Three consecutive years of below average hydrology have reduced water storage in Lake Powell. The current elevation of Lake Powell is 3,633 feet (67 feet from full pool). Current storage is approximately 15.2 million acre-feet (62 percent of capacity). The water surface elevation of Lake Powell will continue to decline for the remainder of this year. The current projection shows that the water surface elevation of Lake Powell will be about 3618 feet (82 feet below full pool) on January 1, 2003. Hydrologic conditions often change, however, and the actual end-of-year elevation of Lake Powell will depend, in large part, on weather conditions in the Colorado River basin from now through the end of the year.
Because of the draw down condition of Lake Powell, and this year's low runoff, releases from Lake Powell in water year 2002 are being scheduled to meet the minimum objective release of 8.23 million acre-feet. This is consistent with the requirements of the 1970 Criteria for Coordinated Long-Range Operation of Colorado River Reservoirs.
This release courtesy Tom Ryan