In 1983, the Hoover Dam spillways were open to release some
of Lake Mead's water.
Each year, the Secretary of the Interior decides whether or not to declare a surplus of Colorado River water.
Surpluses have historically been limited to "flood control" surpluses, which allow the Lower Basin states to use excess water released from Lake Mead to control potential flooding along the Colorado River system.
Every year, the Bureau of Reclamation issues its "Annual Operating Plan for Colorado River Reservoirs" and determines whether or not a surplus condition is expected to exist for the upcoming year.
If additional water is available and demands are greater than 7.5 million acre-feet in the Lower Basin, then the Secretary of the Interior can declare a surplus.
A flood control surplus on the Colorado River was first declared in 1996 and subsequent years through 2002, because of the high storage content in Colorado River reservoirs.
The Water Resource Plan does not assume the availability of flood control surplus during the planning horizon. However, the Southern Nevada Water Authority will use flood control surplus water when it is available and needed to meet demands.
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