BOARD00101 - Laserfiche WebLink

Home Browse Search

, . . ~ Lake Powell Operations in WY1999 July 23, 1999 Page 3 00 Either trigger implicitly recognizes that there is a significant risk of an uncontrolled spill during the peak of the spring runoff. Regardless of any decision to release a BHBF, releases from Glen Canyon would be 'expected to exceed 25,000 cfs, perhaps for an extended period of time. Lake Powell was full (3695.24 feet or 23,566,000 acre-feet) on July 30,1998. Lake Powell began the water year 1999 with 22,403,000 acre-feet in storage. At the end of April 1999 it had been drawn down to a storage content of20,893,000 acre-feet (3677.48 feet) to prepare for the runoff. The April-July runoff forecast ranged from 67% of normal on January I, 1999 to a low of 62 % of normal on April 7th and to the high of 98 % of normal on July 15th. Lake Powell storage probably peaked on or about July 22,1999 at around 23,500,000 acre-feet (3695 feet) or just 5 feet short of full (3700 feet in elevation). Thus, surplus conditions were declared again as they have been since 1996 because Lake Powell was deemed full, 602(a) storage requirements were met, and there was a need for more than a normal water supply in the lower basin. Under these conditions, spill avoidance became the driving factor for making greater than 8.23 maf releases in a normal year. Please note that Lake Mead was fuller than Lake Powell on September 30th and equalization between Powell and Mead therefore was not an issue in water year 1999 nor likely to be in water year 2000. In some previous years, even with surplus deliveries, Lake Mead flood control operations have caused Mead contents to drop below Powell contents and trigger equalization. Projections for operations in water year 2000 indicate the same scenario should occur again under average water supply conditions. In short, operations at Powell on tlle whole for water year 1999 can be described as the regulated passage of inflow. I hope this adequately addresses you request.