Water year 2002 has been an extremely dry year in the Colorado River Basin. Extreme to exceptional drought conditions exist in Colorado, New Mexico, Utah and Wyoming within the Colorado River Basin. Looking back at the past 100 years, there has only been two years prior to 2002 with such extremely dry year-long conditions: 1934 and 1977.
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 in 1963. The previous low occurred in 1977, when April through July inflow to Lake Powell was 1.28 million acre-feet. Much below average precipitation with a poor snowpack this past winter contributed to this year's very low inflow. There has been little relief since. Precipitation this summer continues to be significantly below average, and inflow is expected to continue to be well below normal through the remainder of the summer and into the fall. Observed inflow into Lake Powell is currently 3,600 cfs (August 22, 2002). The historic average inflow into Lake Powell in late August is about 9,500 cfs.
A total of about 890,000 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.
Releases in September, 2002 will be lower with about 480,000 acre-feet scheduled to be released. On Mondays through Fridays in September, daily fluctuations will likely vary between a low of about 5,000 cfs (during late evening and early morning off-peak hours) to a high of about 10,000 cfs (during daylight hours and early evening on-peak hours). On Saturdays during September, releases will likely vary between a low of about 5,000 cfs during off-peak hours, to a high of about 9,000 cfs during on-peak hours. On Sundays, releases will likely vary between a low of about 5,000 cfs during off-peak hours to a high of about 8,100 cfs during on-peak hours.
Releases in October, 2002 will likely be similar to September. A total of 492,000 acre-feet is currently scheduled to be released in October.
Drier than average conditions have now prevailed for the past three years in the Colorado River basin. 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. It is expected that water year 2002 unregulated inflow will be about 24 percent of average. These three consecutive years of below average hydrology have reduced water storage in Lake Powell. The current elevation of Lake Powell is 3,630 feet (70 feet from full pool). Current storage is approximately 14.9 million acre-feet (61 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