Operations
Releases from Glen Canyon Dam will be lower in September than August. Releases in August averaged about 14,600 cubic feet per second (cfs) with a total of 900,000 acre-feet released. In September, releases will average 8,000 cfs with a total of 476,000 acre-feet scheduled to be released. On Mondays through Saturdays (except for Labor Day) in September, daily fluctuations due to load following will likely vary between a low of 5,000 cfs (during late evening and early morning off-peak hours) to a high of 10,000 cfs (during late afternoon and early evening on-peak hours). On Sundays (and on Labor Day), releases will be 5,000 cfs from 7 pm until 7 am, and 8,000 cfs from 7 am until 7 pm.
Releases from Glen Canyon Dam in October and November of 2003 are currently scheduled be 492,000 acre-feet and 476,000 acre-feet respectively, with the same load following pattern as September.
Because of the draw down condition of Lake Powell, releases from Lake Powell in water year 2003 are being scheduled to meet the minimum objective release of 8.23 million acre-feet. This is consistent with the requirements of the Criteria for Coordinated Long-Range Operation of Colorado River Reservoirs.
Basin Hydrology
Drought in the Colorado River basin continues. Inflow volumes have been substantially below average this year with water year 2003 being the 4th consecutive year with below average inflow to Lake Powell. April through July unregulated inflow to Lake Powell in 2003 was 3.91 million acre-feet, only 49 percent of the 30 year average. Total unregulated inflow for water year 2003 will likely be about 51 percent of average.
Snow accumulations in water year 2003 were again well below average levels. Additionally, what snowpack there was in the Upper Colorado River basin this year melted earlier than normal, with the runoff for the most part, being completed by late June. This has resulted in very low summer flows. Inflow to Lake Powell in July tallied up to only 350,000 acre-feet or 22 percent of average. Summer thunderstorms can help augment river flows in the summer, but thus far there has been only limited monsoonal precipitation in the Upper Colorado River basin. Unregulated inflow to Lake Powell in August will likely be only 24 percent of average. Inflow to Lake Powell on August 28, 2003 was 4,800 cfs, 50 percent of what is usually seen in late August.
Total unregulated inflow into Lake Powell in water years 2000 and 2001 was 62 and 59 percent of average, respectively, and only 25 percent of average in 2002. Inflow in 2002 was the lowest ever observed since the completion of Glen Canyon Dam in 1963. These low inflows have reduced water storage in Lake Powell. Lake Powell reached a low water surface elevation this spring at 3605 feet (95 feet from full pool) on May 1, 2003. The lake then rose in response to snowmelt-runoff, reaching a peak on June 23, 2003 at 3616.6 feet. The current elevation of Lake Powell is 3,604.8 feet (95.2 feet from full pool). Current storage is approximately 12.2 million acre-feet (50 percent of capacity). The water surface elevation at Lake Powell will likely continue to decrease for the remainder of the year. Under expected inflows, Lake Powell will likely be near elevation 3600 feet on January 1, 2004.
This release courtesy Tom Ryan.