Partnership Protects Water Supplies For Phoenix And Avondale

AMWUA cities routinely build partnerships to make sure they can deliver safe, reliable and affordable water to their residents all day every day. The cities share the cost of building and expanding water and wastewater treatment plants and share underground storage and recharge facilities that replenish aquifers. More recently, cities have been collaborating to make sure they can efficiently bolster their water supplies during times of shortages. The most recent examples are two agreements about to be signed by the Cities of Avondale and Phoenix. This partnership began during an informal brainstorming session after a meeting of the AMWUA Water Resource Advisory Group. It will end by helping to solve a challenge for each city. 

A Solution for Phoenix: The City of Avondale receives an allotment of Salt and Verde River water each year delivered through the Salt River Project ’s (SRP) canal system. The city receives an average of 7,000 acre-feet. (An acre-foot is enough water to serve three average Arizona families for a year.) Part of this water delivered by SRP is captured in a 72-acre wetlands project within the Crystal Gardens residential development. The remainder is transferred through a pipe that bypasses the wetlands and empties into Avondale’s McDowell Recharge Facility near the Agua Fria River. This water collects in four basins where it percolates back into Avondale’s aquifer. The McDowell facility has the capacity to add or “recharge” 20,000 AF of water but Avondale uses only about half of that capacity. 

The City of Phoenix stores some of its allotment of Colorado River water underground, but the city is running out of storage space. Avondale has agreed to store 5,000 AF of Phoenix’s Colorado River water each year in its McDowell Recharge Facility and SRP has agreed to deliver it. 

During a water shortage an exchange would happen. Avondale would pump Phoenix’s stored water from the aquifer through Avondale’s existing 16-well system and deliver it to its customers. In exchange, Phoenix would receive Avondale’s allotted Colorado River water for its customers. This agreement allows each city to quickly respond to future water shortages at a reasonable cost to their residents. An aquifer holds a finite amount of water , so the additional water stored by Phoenix also keeps Avondale’s aquifer healthier. Water would be recovered in the same general location where it was stored, which is the most sustainable form of underground storage and recovery . 

A Solution for Avondale: Colorado River water is delivered to the Phoenix Metro Area through Central Arizona Project ’s (CAP) canal system. In addition to Avondale’s allotment of river water delivered by Salt River Project, the city also has a 5,416 AF allotment of Colorado River water. Avondale does not physically receive its allotment of Colorado River water. The CAP canal that delivers Colorado River water to the Phoenix Metro area is far from Avondale and it is too costly for the city to build infrastructure to move the water. Instead, Avondale stores its Colorado River allotment in a CAP facility known as the Hieroglyphic Mountains Recharge Project, which is 21 miles from Avondale’s city limits. 

In exchange for storing the water in the Hieroglyphics aquifer, state law allows Avondale to pump a similar amount of groundwater from the aquifer beneath the city. While this exchange is legally called “recovered” water, it is not healthy for Avondale’s finite aquifer. Avondale decided it wanted to find an efficient way to have its Colorado River water delivered and reduce the amount of groundwater it pumps from its aquifer. Here’s how its agreement with the City of Phoenix works.

• Phoenix water treatment plants sit close to canals and can easily receive Colorado River water, treat it and distribute it to its customers.
• One of Phoenix’s drinking water distribution pipes runs along 107th Avenue and Indian School Road, which happens to be Phoenix’s border with Avondale.
• Phoenix has agreed to receive Avondale’s 5,416 AF of Colorado River water at its Deer Valley Water Treatment Plant. 
• Avondale has agreed to build a connection to Phoenix’s main distribution pipe that runs along its border. The connection will allow Avondale to receive its Colorado River allotment through the Phoenix distribution line and transport the water into its drinking water system.
• Avondale will further treat the Colorado River water to balance its chemistry to match Avondale’s delivery system. This prevents corrosion of the system and taste or odor issues common to surface or river water when it is introduced into a system delivering primarily groundwater. 

This new water will help Avondale save more water in its aquifer, keeping the city ready to pump, treat and deliver water to its customers in times of shortages. 

Well-planned water supplies fuel desert cities’ economies – and their futures. The water agreements between Avondale and Phoenix are just two examples of the innovative collaborations that protect Phoenix Metro’s water supplies. 

Photo: Jim Painter

For 49 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org .