Las Vegas Sun

June 17, 2018

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Nevada to store water in Arizona

Southern Nevada water officials have struck a deal to store up to 1.2 million acre-feet of Colorado River water underground in Arizona to help ensure the Las Vegas Valley has enough water over the next 50 years.

The Southern Nevada Water Authority and the Colorado River Commission are expected to approve the historic agreement on Tuesday at a special joint meeting. A formal signing ceremony for the interstate water savings contract will be scheduled in July.

The deal allows the water authority to bank any unneeded portion of its annual allotment of Colorado River water in Arizona wells, water authority General Manager Pat Mulroy said. The water can be withdrawn in the future if there is a shortage -- natural or manmade -- on the river.

This first interstate agreement lasts until June 1, 2050, water authority spokesman J.C. Davis said.

Nevada this year was given rights equal to California and Arizona -- the other Lower Colorado River Basin states -- in claiming a portion of the river's surplus, when one is declared. This year a 625,000 acre-feet surplus was divided between Nevada and California. Arizona officials said the state did not need the extra water.

An acre-foot is enough water to supply a family of four to five for a year. Nevada's annual allotment of Colorado River water is 300,000 acre-feet a year, compared with 4.4 million acre-feet for California and 2.3 million acre-feet for Arizona.

Under the pending storage agreement, Nevada would not actually draw water out of the Arizona wells. In times of shortage, Arizona would use the stored water, and Nevada would draw a portion of Arizona's share from the Colorado River.

Arizona officials will decide by Nov. 1 each year how much water can be stored for Nevada. Nevada cannot store any water until Arizona's needs are met, according to the agreement. The most water Nevada can store in any year is 100,000 acre-feet. How much water authority customers will pay for storage will be determined annually.

The water authority will pay all of Arizona's costs to store and recover the water.

A proposal to store water in Arizona has been in the works since 1991, when the water authority became the regional agency to distribute water from Lake Mead to the area's cities and Clark County.

In February 1993 the water authority board authorized a demonstration project for underground storage of the Colorado's water in Arizona. A total of 50,000 acre-feet was put in place.

The Bureau of Reclamation allowed the banking of unused river water in a rule adopted in November 1999, leading to negotiations between Arizona and Nevada.