BOULDER CITY, Nev. – Based on the August 24-Month Study, which is the Bureau of Reclamation’s monthly operational study, the water release from Lake Powell to Lake Mead for water year 2015 will be 8.23 million acre-feet (maf). This is an increase from the 2014 release of 7.48 maf, which was the lowest release since Lake Powell filled in the 1960s.
Based on the August 24-Month Study, Lake Mead will operate under normal conditions in calendar year 2015, with water users in the Lower Colorado River Basin and Mexico receiving their full water orders.
The August 24-Month Study projections are used in accordance with the 2007 Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead (2007 Interim Guidelines) to determine the amount of water released from Lake Powell to Lake Mead for each water year (October 1 to September 30).
The 2007 Interim Guidelines allow water managers to plan ahead for varying Colorado River reservoir levels, with a greater degree of certainty about annual water deliveries. The 2007 Interim Guidelines also define the reservoir levels that would trigger delivery shortages and specify the reduced delivery amounts in the Lower Colorado River Basin.
The Upper Colorado River Basin runoff in 2014 was 94% of average, compared to only 47% in 2013 and 45% in 2012. Despite this near-average runoff, Lake Mead is currently at elevation 1,080 feet, its lowest elevation since the lake filled in the 1930s, due to the 15-year drought that began in 2000.
Under the 2007 Interim Guidelines, another review of the conditions at Lake Powell and Lake Mead will occur in April 2015. Based on an analysis of those projections in the April 24-Month Study, Lake Powell’s water releases could be increased to 9.0 maf for water year 2015.
Despite a greater release of 8.23 maf from Lake Powell, the elevation of Lake Mead is projected to continue to decrease in 2015. Currently the longer-term projections from Reclamation’s hydrologic models show the first chance of reduced water deliveries in the Lower Basin in 2016. These updated projections will be available later in August.
Reclamation is the largest wholesale water supplier and the second largest producer of hydroelectric power in the United States, with operations and facilities in the 17 Western States. Its facilities also provide substantial flood control, recreation, and fish and wildlife benefits. Visit our website at www.usbr.gov.