AMWUA Blog

Feb 22 2021Share

Improving Recovery of Stored Water for a Drier Future

By Warren Tenney

Over a month into the 2021 legislative session, Arizona’s lawmakers have introduced a record number of bills – more than 1,700. Included in those bills is legislation proposed by AMWUA that strives to better prepare Arizona for Colorado River shortages by making a technical yet important change to an Arizona water law.

Senate Bill 1147 relates to the retrieval of water stored underground by the Arizona Water Banking Authority (AWBA). The AWBA was created in 1996 to take Colorado River water diverted through the Central Arizona Project (CAP) canal and store it underground in the Maricopa, Pinal, and Pima counties. In the mid-’90s, Arizona was not utilizing its full legal entitlement to Colorado River water, so the Water Bank was created to recharge that unused water in Central Arizona aquifers for use in times of drought and shortage. Over the past two and half decades, AWBA has stored over 3.6 million acre-feet of Colorado River water.

Today, water users from Central Arizona utilize far greater volumes of Colorado River supplies delivered by CAP. Additionally, decades of drought and overallocation have strained the River’s ability to meet all water demands throughout the Colorado River Basin. As a result, there is far less excess Colorado River water available for AWBA to recharge into aquifers.

For some time, Arizona’s water community has anticipated these changes and adjusted from prioritizing Colorado River water storage to focusing on retrieving, or recovering, the water stored underground by AWBA. The majority of water stored underground was purchased by AWBA with property tax revenues from Maricopa, Pinal, and Pima counties. That stored water is intended to serve as a backup supply to the municipal water providers with high-priority Municipal and Industrial subcontracts for Colorado River water in a shortage.

Every acre-foot of water stored by the Water Bank generates a long-term storage credit that can be used to pump an equivalent amount of water later on. In the statutes, AWBA is required to transfer its long-term storage credits to the Central Arizona Water Conservation District (CAWCD), the entity that oversees the Central Arizona Project. CAWCD was made responsible for recovering Water Bank credits for delivery to the municipal water providers when their Colorado River supplies are cut during shortage. At the time, it was assumed that CAWCD could utilize those credits to pump the stored water and deliver it through the CAP canal to the municipal water providers.

In recent efforts to improve the implementation plan for recovering water stored by AWBA, stakeholders identified that it would be useful if AWBA could distribute its credits directly to the municipal water providers. In some instances, those providers can add the long-term storage credits to their water supply portfolio and recover the water themselves through existing infrastructure or partnerships with other water users.

SB 1147 would add statutory language to make this concept possible and allow AWBA to distribute its long-term storage credits to municipal water users or CAWCD. This would increase AWBA’s flexibility to decide the most effective way to distribute its credits to recover the water on those entities’ behalf. Many municipal water providers operate groundwater wells capable of recovering water stored underground. In near-term shortages, it is anticipated that receiving credits directly from the Water Bank will be an efficient way to distribute the stored water and will lead to cost-savings as municipalities can utilize existing infrastructure. Now is the time to make this change and assist recovery planning efforts. It will be important to have this an option with the Colorado River projected to enter into a Tier One Shortage in 2022. Deeper shortages could trigger a need to recover Water Bank supplies to support municipal water providers.

The creation and pursuit of this legislation have been a collaborative and transparent process. The initial concept of directly distributing the Water Bank’s credits to municipal providers came out of the Recovery Planning Advisory Group – a collection of water stakeholders who meet regularly to plan for recovery implementation. AMWUA worked with AWBA, CAWCD, Arizona Department of Water Resources (ADWR), and other water stakeholders to draft legislative language. Once stakeholders agreed to the draft language, the legislative proposal was brought before several public bodies and groups, including the AWBA Commission, CAWCD Board of Directors, AMWUA Board of Directors, and at the Vetting Forum for Water before it was officially introduced as legislation.

This focus on transparency and consensus has proven to be beneficial. In 2020, this legislation passed the Arizona State Senate unanimously before the legislative session was interrupted due to the COVID-19 pandemic. This year, the proposal passed the Senate unanimously again and is moving through the State’s House of Representatives' legislative process. As the AMWUA cities and other municipal water providers continue to prepare for eventual shortages on the Colorado River, SB 1147 presents an opportunity to add another tool for enhancing the reliability and security of their water supplies.


The water world is complex, diverse, and deep in terminology. So we’re here to help translate with the AMWUA Water Glossary


For over 50 years, the Arizona Municipal Water Users Association has helped protect our member cities’ ability to provide assured, safe, and sustainable water supplies to their communities. For more information, visit www.amwua.org.

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