A team of researchers from Arizona’s three public universities has released a report outlining where the state can capture water that would otherwise evaporate or transpire before recharging groundwater. Along with the report, the team also delivered tools and methods that state water managers can use to act on that information.
The final report comes as Arizona confronts uncertainty over its Colorado River supply.
The effort, dubbed the Arizona Tri-University Recharge and Water Reliability Project (ATUR), brought together the University of Arizona (U of A), which led the research, along with Arizona State University (ASU) and Northern Arizona University (NAU). The project was launched at the request of the Arizona Department of Water Resources (ADWR) and funded by the Arizona Board of Regents (ABOR) through the Technology and Research Initiative Fund (TRIF).
More than 95% of Arizona’s precipitation never reaches a stream or replenishes groundwater, the researchers found, evaporating or passing through plants first. They note that capturing even a small percentage of that water could add meaningful supply for the state.
As part of their work, the team modeled the water budget for each of Arizona’s 51 groundwater basins. They found that total water storage is declining statewide, a trend they associate with hotter conditions and rising evaporative demand.
The team also projected statewide water supply through the end of the century. Among those findings, the report identifies the Mogollon Rim as the area best positioned to produce large volumes of capturable water, which it attributes to higher precipitation there relative to evapotranspiration.
To further help water managers, the team built three companion tools for the report. The first, dubbed the Decision Support Framework, is a step-by-step screening tool that walks users through 10 questions. These range from water management goals to mapping out implementation and are meant to help them decide whether a given location is worth a closer look.
The second tool, a Recharge Opportunities Matrix, catalogs water capture and recharge strategies organized by landscape type. In urban areas, for example, it lists stormwater capture tools such as drywells and retention and detention basins, along with smart subdivision design.
The matrix also lists green stormwater infrastructure systems such as roof-runoff harvesting, rock detention structures and permeable pavement. For more natural or higher-elevation landscapes, the strategies shift toward land management, including forest thinning and flood and fire management.
The third tool is a set of Groundwater Basin Profiles, delivering analysis down to the local level. The team composed profiles for each of Arizona’s 51 groundwater basins, covering current and projected precipitation, recharge, runoff and temperature. The tool includes maps showing where recharge potential is highest within a given basin, along with projections of future water supply conditions.
The report notes that it is meant as an advisory tool, using a scientific foundation to help guide a user to making a decision. It stops short of recommending specific sites or techniques.
The primary theme is what the report calls Opportunistic Recharge Enhancement. The idea is to fold recharge work into already-running projects, typically at lower total cost. For example, a water basin retention pond in a new subdivision, or smart street planning to mitigate and capture floodwaters.
The report cites a Phoenix-area example where they estimate drywells, along with retention and detention basins, already capture about 94,000 acre-feet of stormwater a year. They also estimate that number will grow to about 165,000 acre-feet by 2058 under expected growth.
Flood control is listed as a top candidate for water capture as well. The report notes that Arizona’s flood control districts already hold the authority to build recharge into their facilities, but mostly have not. The report goes on to note that the next logical step is securing partnerships.
Citing the fact that watersheds span jurisdictions, the report frames collaboration with federal land agencies, flood-control districts, transportation officials, tribes and private landowners as essential. It also notes that the common factor stopping water capture projects from moving forward is funding, while noting that combining stormwater mitigation with recharge infrastructure might open the pool of potential partners.
The project has been extended into 2027, with the team’s focus shifting from mapping where Arizona can capture water to helping water managers decide where to begin.
Photo by Mark Stebnicki from Pexels
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