Arizona Water Bank

The Water Authority approved an agreement in December 2004 with Arizona that allows Nevada to store water in Arizona's groundwater aquifer.

Under the agreement, Nevada will pay Arizona to store unused Colorado River water for future use.

An amendment to a 2001 groundwater banking agreement, this pact solidifies the quantity of water to be stored, guaranteeing Nevada access to the entire 1.25 million acre-feet (more than 400 billion gallons of water). Under the terms of the agreement, SNWA can recover 20,000 acre-feet of water in 2007 and 2008 and 30,000 acre-feet of water in 2009 and 2010. Beginning in 2011, the parties agreed to a maximum recovery rate of 40,000 acre-feet per year until the bank reserves have been fully exhausted.

Because the withdrawals will be taken from Lake Mead, Nevada also will receive return-flow credits for the portion of water used indoors, further extending the value of this pact.

Under the terms of the agreement, SNWA paid Arizona $100 million in 2005, and will make 10 annual installments of $23 million beginning in 2009.

How the banking works

As part of the water banking agreement, Arizona stores available Colorado River water in an underground aquifer. Nevada receives "credits" for the water stored in this groundwater "bank."

When Nevada needs to recover some of this banked water, it uses its storage credits and withdraws a portion of Arizona's Colorado River water directly from Lake Mead. Arizona then withdraws the same amount of water from its groundwater aquifer.