Three factors that significantly affect the water levels in lakes Powell and Mead are:
As a result of these conditions, the Colorado River users have taken actions to protect Lake Mead’s elevation from dropping to critical levels.
Releases and diversions are made from Lake Mead to meet water deliveries in Arizona, California, Nevada, and Mexico, while Lake Powell is operated to deliver water from the Upper Basin to the Lower Basin. As part of the 2007 Interim Guidelines, water levels in these two reservoirs are coordinated to allow better management of the Colorado River supply.
Lake Mead water levels are important because they determine whether a shortage is declared on the Colorado River. All the states that share the river, the federal government and Mexico previously agreed to shortage "trigger levels" and resulting reduced delivery amounts in the 2007 Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead. These were developed based on data that was available at that time, very early in the Colorado River drought. Now, nearly 10 years later it is apparent that those guidelines are not enough. New river flow projections indicate that Lake Mead levels could drop to the point of seriously impacting power generation and water availability, despite the 2007 Interim Guidelines.
If a shortage is determined in the near future, quantified reductions in deliveries to Arizona, Nevada, and Mexico (pursuant to Minute 323) would be implemented as shown below:
Jan 1, Elevation*
*Projected Jan 1 Elevation from August 24-month study. California takes no shortage