California

Recharge refers to the replenishment of an aquifer's groundwater. An aquifer is a layer of underground sand, gravel, or spongy rock where water collects. Natural recharge takes place when rainfall, streamflow, or melting snow percolates into the ground.

Artificial recharge occurs when water is put into special basins or is directed into modified stream channels and allowed to sink into the ground. Artificial recharge also can take place when water is pumped directly in the aquifer through special wells.

Recharge takes advantage of water supplies available now and stores them for future use. Recharge also allows the slow introduction of new water supplies into our drinking water system by blending the new source with existing groundwater. Pilot recharge studies are done in advance of developing large-scale recharge facilities to determine recharge rates and quantities, water quality changes, the ability of the aquifer to store and release recharged water, and costs of recharging the water and pumping it for use.

The City has several recharge projects using CAP water. The Clearwater Renewable Resource Facility consists of two large recharge and recovery sites in central and southern Avra Valley. These projects are capable of recharging up to 140,000 acre-feet (46 billion gallons) of Colorado River water, nearly all of Tucson Water's current annual allocation.