Recharge and Water Reliability

On June 25, 2026, the Arizona Department of Water Resources published the“Recharge and Water Reliability Project Report,” a three-year study by Arizona’s three public universities on increasing groundwater recharge and improving water-supply reliability. Its main findings:

• More than 95% of Arizona’s precipitation returns to the atmosphere through evaporation and plant transpiration. Reducing a small portion of those losses could increase available supply.
• Total water storage statewide is declining, closely associated with hotter, drier conditions.
• The Mogollon Rim/Transition Zone offers the greatest potential for capturing and storing substantial water volumes because precipitation is relatively high compared with evapotranspiration.
• Development and land management can support recharge through better stormwater capture, flood-flow management, forest thinning, fire management, and infrastructure design.

The article does not quantify how many additional acre-feet could be recovered, or establish that all evaporation and plant water use could be converted into usable supply.

Nonetheless, the report’s main implication for Nevada is that groundwater recharge, river flow, and available water must be evaluated together, as required by NRS 533.024 and SB 150.  

These are implications to investigate, rather than Nevada-specific conclusions from the report:

The USGS describes the Muddy–Coyote Springs connection as a regional groundwater system spanning Nevada valleys and documents spring and shallow-groundwater contributions to the Muddy River.  Therefore, a local basin boundary does not necessarily define the full area affected by pumping or recharge. U.S. Geological Survey

For Lake Mead, “captured water” and “additional water” are different accounting questions since stormwater already travels through the Las Vegas Wash toward Mead; SNWA separately returns treated wastewater and earns return-flow credits. A capture project therefore needs to identify the water’s source and existing destination before claiming a benefit. clarkcountynv.gov

Two cautions from the report matter:

• Infiltration is not necessarily aquifer recharge. Water may remain above the water table, support vegetation, or take a long time to reach recoverable groundwater.
• Arizona’s statewide percentages are not Nevada estimates. Its evapotranspiration and recharge figures should not be inserted into Basin 222 or Coyote Springs budgets without local analysis.