When the issue is a reliable water supply, water agencies are willing to not only walk the line, but cross it, including the state line.
In November 1999, the Department of the Interior issued a "final rule" that breaks down state lines when it comes to interstate offstream storage programs of Colorado River water. Limited to the lower basin states of Arizona, California and Nevada, the rule establishes a framework that will, in short, allow Nevada and California to store water in Arizona's vast groundwater basins. The rule seeks to increase water supply efficiency and flexibility on the river.
Created in 1996 to protect Arizona's Colorado River interests and to provide for interstate banking opportunities, the Arizona Water Banking Authority (AWBA) goal is to firm up urban supplies for the state to:
- be used during times of shortages on the river or during Central Arizona Project service interruptions
- help meet the water management objectives of the Arizona Groundwater Code
- factor into American Indian water rights claims settlements
To develop long-term storage credits for the state, AWBA pays to deliver and store Arizona's unused river water in the state's western, central and southern groundwater basins. For each acre-foot stored, AWBA receives a credit that can be used during times of shortage.
And with the interstate provision built into the Interior's rule, Nevada and California are working with AWBA to discuss the possibility of further shoring up their own supplies through the potential storage of surplus supplies in Arizona's basins.
California, through the Metropolitan Water District, would also like to store surplus river water to:
- help maintain a full Colorado River Aqueduct
- lessen impacts in years when less than 1.25 maf is available to MWD
- create a more reliable supply
- firm up long-term reliability by making better use of river surpluses
The Department of Interior has limited the annual amount that California or Nevada can reclaim from the Arizona groundwater bank to 100,000 acre-feet.