SRP stores water for tomorrow

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SRP, working with partnering cities, has developed two groundwater recharge facilities to ensure a reliable and adequate water supply for the Phoenix metropolitan region.

The Granite Reef Underground Storage Project (GRUSP) and the New River-Agua Fria River Underground Storage Project (NAUSP) are designed to store water underground for future use.

How it works


GRUSP (top) and NAUSP allow SRP to store excess CAP and surface water underground for use during dry years.

Through artificial groundwater recharge, water is retained in huge, porous earthen basins and allowed to seep into the natural underground aquifer below. View a diagram that illustrates how water is captured and stored.

An aquifer is the porous material in which water is contained underground. It can consist of gravel, fractured rock, sand, silt or a blend of such materials and vary in thickness from a few feet to 1,000 feet or more.

Water is stored in the aquifer and withdrawn by well-pumping when needed.

GRUSP and NAUSP enable Arizona to maximize the use of its Colorado River entitlement and help the state reach its "safe yield" goal. Safe yield is the equilibrium between the amount of groundwater pumped from an aquifer and the amount recharged into it.

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GRUSP facts

Construction: Original four basins completed in 1994; additional basins completed in 1999, 2000 and 2005
Partners: Operated by SRP; owned by SRP, Chandler, Gilbert, Phoenix, Mesa, Scottsdale and Tempe
Water sources: Water from the Salt and Verde rivers, Central Arizona Project water via the South Canal, and reclaimed water via pipeline from Mesa water reclamation facility
Number of basins: Seven
Surface area (approximate): 217 acres
Storage capacity: 93,000 acre-feet per year permitted
Location: On Salt River Pima-Maricopa Indian Community land, in the Salt River bed just west of SRP's Granite Reef Diversion Dam
Distinction: First major recharge facility in the state, and one of the largest of its kind in the U.S.

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NAUSP facts

Construction: Completed in 2007
Partners: Operated by SRP; owned by SRP and Avondale, Chandler, Glendale and Peoria
Water source: Water from the Salt and Verde rivers, Central Arizona Project water via the Grand Canal, and reclaimed water via pipelines from Glendale and Peoria water reclamation facilities
Number of basins: Six off-channel basins
Surface area (approximate): 125 acres
Storage capacity: 75,000 acre-feet per year permitted
Location: In Glendale, about one mile west of University of Phoenix Stadium
Distinction: First major recharge facility in the West Valley

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