Colorado River Seven States Agreement
In December 2007, the federal government and the seven states of the Colorado River Basin established guidelines for coordinated operation of Lakes Powell and Mead under low-reservoir conditions and for shortage allocations among the Lower Basin states. An ongoing severe drought and potential for a major shortfall in supplies led to the agreement.
In addition to water supply, there is concern that if Lake Mead were to drop to elevation 1,050 feet, hydroelectric-generation capacity at Hoover Dam would be compromised. Much of Hoover Dam’s power is used by Southern California cities and the Metropolitan Water District to pump supplies from Lake Havasu, through the 242-mile Colorado River Aqueduct, to Lake Mathews.
Another signature component of the Seven States Agreement is the Intentionally Created Surplus Program. It allows Lower Basin entities to create water credits through conservation measures such as importing water, lining canal, land fallowing, and take delivery of those water credits from Lake Mead at a future date. Entities in the Lower Basin states can store up to 2.1 million acre-feet of Intentionally Created Surplus water in Lake Mead for their future use; with 5 percent credited to the overall system. This water could help keep Mead’s elevation higher and it could help prevent the need to declare a shortage – and curtail water deliveries – in the Lower Basin.
Colorado River Seven States Agreement Overview
Under terms of the 2007 Seven States Agreement, the first shortage in the Lower Basin would occur if Lake Mead’s elevation were to drop to 1,075 feet. Arizona’s annual water apportionment would be decreased to 2.48 million acre-feet (normal allocation is 2.8 million acre-feet) while Nevada would receive 287,000 acre-feet (normal allocation is 300,000 acre-feet). If Mead were to drop below 1,050 feet Arizona would get 2.4 million acre-feet and Nevada would get 283,000 acre-feet. And if the reservoir were to drop below 1,025 feet, Arizona would receive 2.32 million acre-feet; Nevada, 280,000 acre-feet. In any of these scenarios California would receive its full 4.4 million acre-feet, but would not be able to take delivery of ICS water during a Lower Basin shortage.
Further, if Lake Powell is higher than Lake Mead, it is required to release additional flows, simplifying the agreed-upon formula used to determine equalization.