Arizona has an innovative program called the Underground Water Storage, Savings and Replenishment Program.
This program, which is managed by the Arizona Department of Water Resources, allows surface water and reclaimed water not needed today to be banked – stored underground – for future use.
Water is stored underground through two methods:
Direct Recharge: In this method, water is delivered to specially constructed basins that facilitate the infiltration of water into the ground. The water percolates and eventually reaches the existing groundwater aquifer, storing the water underground for future use.
The Gila River Indian Community, the source of Gila River Water Storage water, is permitted to recharge Central Arizona Project water at the Granite Reef Underground Storage Project, the New River-Agua Fria River Underground Storage Project, and the Superstition Mountains Recharge Project, all of which are located in the Phoenix Active Management Area.
The community is also conducting tests to locate suitable direct recharge facilities on the Gila River Indian Reservation.
Indirect Recharge: Indirect recharge is performed at irrigation districts that are permitted by ADWR as groundwater savings facilities.
The concept is that irrigation districts with legal rights to pump groundwater can use CAP or reclaimed water in lieu of pumping groundwater. Thus, groundwater is "saved," hence the name "groundwater savings facility," and long-term storage credits are issued to the entity that delivered the CAP water or reclaimed water to the irrigation district.