Active Management Area (AMA) 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 example are two agreements 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 Avondale: Colorado River water is delivered to the Phoenix Metro Area through the Central Arizona Project’s (CAP) canal system. The city has a contract for 5,416 AF allotment of Colorado River water. Avondale does not physically receive their Colorado River water, instead it is sent to the CAP Hieroglyphic Mountain Recharge facility; 21 miles away 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 recovered water, it is not necessarily healthy for Avondale’s finite aquifer.
Avondale could request the Salt River Project deliver the Colorado River water through its canal system, but transportation costs are too high and too much of the water would evaporate along the way. In other words, too little water at too great an expense.
The IGA with Phoenix, called Treatment and Delivery, offers Avondale the new opportunity to have its Colorado River water delivered and reduce the amount of groundwater it pumps from its aquifer. Here’s how the agreement work:
- Phoenix water treatment plants sit close to canals and can easily receive Colorado River and the Salt 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 boarder 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 started construction on the interconnection to Phoenix’s main pipe that runs along its border. The connection will allow Avondale to receive its Colorado River allotment from the Phoenix distribution line on its boarder and transport the already-treated drinking water into its drinking water system. The connection is estimated to be finished by December 2020!
- Avondale will add additional treatment to polish the Colorado River water to balance its chemistry so it matches Avondale’s delivery system. This prevents corrosion of the system and taste/odor issues common to surface water being introduced into a system primarily serving groundwater.
This new water will help Avondale save more water in its aquifer, keeping the city’s aquifer ready to pump in time of water shortages.
A Solution for Phoenix: In addition to the City of Avondale’s CAP allotment the city receives Salt River Project (SRP) water each year delivered through SRP’s canal system. Avondale’s SRP allotment can change year to year depending on the watershed, but the average amount of SRP stored water delivered to Avondale is about 7,000 AF (An acre-foot is enough water to serve three average Arizona families for a year.) Part of this SRP water 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 and currently 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. SRP has agreed to deliver Phoenix’s Colorado River water through its canals to Avondale.
During a water shortage an exchange would happen. Avondale would pump Phoenix’s stored water and, when needed, retrieve it from the aquifer through Avondale’s existing 16-well system and deliver it to its customers. In exchange, Phoenix would receive and treat 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 also keeps Avondale’s aquifer healthier. Water is recovered in the same general location where it was stored, which is the most sustainable form of underground storage and recovery.
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.