BY: Warren Tenney

Multiple Water Sources Ensure Sustainability for Cities

Published Sep 02, 2019

How can so many people live in the middle of the desert? Well it’s because we are acutely aware that we must continually plan and invest to ensure safe, reliable, and sustainable water supplies for today and the future. That is precisely why the cities understand the importance of a diverse water portfolio and have invested in multiple sources of supply rather than relying on just one, like many areas across the country.

Here in the Valley the water we utilize is not just from the Colorado River, which represents only a portion of your city’s water portfolio. The AMWUA member cities also receive water from the Salt and Verde Rivers, and utilize reclaimed water as well as a small portion of groundwater. By having multiple sources of supply, the cities are better prepared for the long-term, as well as any short-term challenges that may arise. The wellbeing of our communities and economies depends on the reliability of water, especially when living in a desert.

Although each city’s individual portfolio may slightly differ from that of their neighbor’s, most utilize the following water sources.

Salt and Verde Rivers

  • Each city has an agreement to receive water from the Salt River Project (SRP) , which is the largest provider of water to the Phoenix Metropolitan area.
  • SRP operates eight dams, seven reservoirs and 131 miles of canals that bring water from the Salt and Verde rivers to the Valley.  Roosevelt Lake is the largest reservoir in SRP’s system.
  • Reservoir water can be blended with groundwater and Colorado River water to meet the region’s full need. This redundancy in supply enhances water reliability.

Colorado River

  • Each city has an allocation for Colorado River water, which is delivered by the Central Arizona Project (CAP) .
  • CAP is a 336-mile engineering marvel that brings Colorado River water to central and southern Arizona, where 80 percent of the state’s population resides.
  • With 14 pumping plants, CAP lifts Colorado River from Lake Havasu, which is at sea level, to an elevation of 2,800 feet at the end of the canal in Tucson.

Reclaimed Water

  • All AMWUA cities clean and re-use their wastewater . Nearly 100 percent of what was once wastewater is treated by the cities and put to beneficial use. 
  • In addition to water sent to the Palo Verde Nuclear Generating Station, cities also use treated wastewater to irrigate parks, create fishing lakes and wetlands, or to recharge their aquifers.
  • Wastewater is a renewable water source, most often called recycled water or reclaimed water.
  • All reclaimed water used in parks, golf courses, HOA common areas, school playgrounds or church campuses is treated to what the State deems as A+ quality.
  • Grade A+ quality means the water is treated and disinfected until there are no routine, detectable disease-causing bacteria and has removed nitrogen compounds, which can contaminate groundwater. 


  • The AMWUA cities understand the importance of preserving groundwater and have been stalwart supporters of the 1980 Groundwater Management Act.
  • The goal of the landmark Groundwater Management Act is to achieve "safe-yield," meaning that no more groundwater is pumped than is replenished annually.
  • Groundwater remains the ultimate backup for a dire extended drought and water shortage.

Since Arizona leaders made tough decisions early on with the 1980 Groundwater Management Act and requiring the 100-year Assured Water Supply designation, and because Valley cities have diligently prepared for life in the desert through strong water policy, we are able to prosper and enjoy our way of life here in the Valley.

As we plan for a drier future, the AMWUA cities will continue wise water stewardship by investing, protecting and enhancing our water supplies which will ensure viability into the future. Because in the end, having more than one source of water means a stronger economy for the Valley and a more sustainable way of life for all of us here in the desert.

For 50 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 .

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