Glen Canyon Dam Operations
The monthly release volume for January 2009 is scheduled to be 800,000 acre-feet. Daily average releases during January will be about 13,000 cfs. Monday through Friday releases will peak each afternoon to about 17,000 cfs with early morning releases of approximately 9,000 cfs. Weekend afternoon peak releases will be about 16,750 cfs with morning low releases near 9,000 cfs. The currently scheduled release volume for February 2009 is 600,000 acre-feet which will result in an average daily release of 10,800 cfs. Afternoon peaks will likely be about 13,800 cfs and early morning releases will likely be about 7,800 cfs.
Snowpack conditions in the Upper Colorado River Basin improved significantly during the month of December. On December 1, 2008 the snowpack above Lake Powell measured only 57% of average. By December 31, 2008 this snowpack had improved to 108% of average. As of January 12, 2009 the snowpack measured 110% of average.
The Colorado Basin River Forecast Center has issued the first water supply forecast for 2009. The Lake Powell forecasted unregulated inflow for the period from April through July 2009 is 8.0 million acre-feet (maf) (101% of the average during the period from 1971 to 2000). Based on this forecast, Reclamation is currently projecting a shift in operations from Upper Elevation Balancing to Equalization in April 2009 (see Interim Guidelines Section 6.B.3). For this reason, the January 24-Month Study projects the annual release from Lake Powell during water year 2009 to be 9.236 maf. As forecast conditions change, Reclamation will update these projections monthly.
Upper Colorado River Basin Hydrology
Precipitation rates during October and November 2008 were well below normal at 55% and 80% respectively. In December, however, conditions improved significantly with the estimated precipitation rate of about 180% of average. The overall water year precipitation rate through January 12, 2009 is 105% of average.
The Climate Prediction Center outlook for temperature and precipitation over the next 3 months indicates equal chances for both temperature and precipitation in the Upper Colorado River Basin. This means we can likely expect near average temperatures and near average precipitation over the next 90 days.
Upper Colorado River Basin Drought
The Upper Colorado River Basin is experiencing a protracted multi-year drought. Since 1999, inflow to Lake Powell has been below average in every year except water year 2005 and 2008.
In the summer of 1999, Lake Powell was essentially full with reservoir storage at 23.5 million acre-feet, or 97 percent of capacity. During the next 5 years (2000 through 2004) unregulated inflow to Lake Powell was well below normal. This resulted in Lake Powell storage decreasing during this period to 8.0 million acre-feet (33 percent of capacity) which occurred on April 8, 2005. During 2005 and 2008 drought conditions eased somewhat with net gains in storage to Lake Powell. On September 30, 2008 the storage in Lake Powell was 14.5 million acre-feet (60 percent of capacity) which is still well below desired levels. Reservoir storage in the Colorado River Basin continues to be below desired levels with the overall Colorado River system storage as of January 1, 2009 of 33.3 maf which is 59.4 percent of capacity.