The Arizona Supreme Court has declined to mandate Governor Katie Hobbs to direct the state's Department of Water Resources (ADWR) to investigate potential groundwater management needs along the upper San Pedro River. This decision upholds a lower appellate court ruling against environmental groups who argued state law requires periodic reviews for "active management areas" (AMAs) to limit groundwater pumping.
In a brief order, the justices did not provide specific reasons for their decision. This leaves intact the Arizona Court of Appeals' conclusion that Governor Hobbs and ADWR are not legally compelled to perform such a study. Appellate Judge Kent Cattani, writing for the unanimous three-judge panel, acknowledged the legal requirement for ADWR to "periodically review" areas for AMA designation. He did not dispute that over two decades have passed since the San Pedro Basin was last reviewed for this purpose. However, Judge Cattani found that the law does not specify the frequency of these reviews or define the term "periodically," thereby granting the department discretion in determining how often to conduct them.
This interpretation contrasts with the view expressed by Attorney General Kris Mayes. Prior to the environmentalists' lawsuit, Mayes communicated with ADWR Director Tom Buschatzke, emphasizing the statutory requirements. Mayes criticized the department's lack of action, noting that "Two studies of a single basin in a 40-year period does not satisfy the statutory duty." She inquired why ADWR had been unable to comply. Governor Hobbs responded to Mayes's letter, suggesting direct communication with her office regarding concerns about agencies under her oversight. Following the Supreme Court's decision, an aide to Mayes, Richie Taylor, indicated that there is a need for legislators to update the statutory definition of "periodically." Taylor stressed the importance of understanding statewide water supplies, particularly in light of Colorado River cuts.
The lawsuit, filed in 2024 by the Center for Biological Diversity and the San Pedro Alliance, contended that ADWR failed its "mandatory duty" to conduct a review to ensure "long-term, reliable groundwater supplies" in the San Pedro basin. It also argued the governor violated her constitutional duty to "take care that the laws be faithfully executed" by not ordering the review. Such a study would assess whether the basin should be designated an AMA, which imposes limits on groundwater pumping. Arizona's 1990 groundwater code initially established four AMAs, now expanded to eight, with some formed by resident votes and others by ADWR studies based on water use and quality issues.
The San Pedro River is noted as the last undammed, free-flowing river in the desert Southwest, making its ecosystem particularly fragile. Groundwater serves as the sole water source for communities within the basin, including Sierra Vista, Benson, Bisbee, Tombstone, Huachuca City, and the Fort Huachuca Military Reservation. Century-long public and private water use has contributed to the degradation of the river's ecosystem and altered its flow. The basin also encompasses the San Pedro Riparian National Conservation Area, established by Congress in 1988 to protect its unique resources, with Congress having reserved water to fulfill the area's purposes.
Appellate Judge Cattani concluded that the challengers were not entitled to "mandamus" relief, which is a court order compelling an official to perform a specific, non-discretionary act. He determined that the law's use of "periodically" allows for departmental discretion, thus not meeting the "ministerial" act standard required for such relief. Robin Silver, a co-founder and board member of the Center for Biological Diversity, declined immediate comment on the Supreme Court's decision. Previously, Silver had criticized Governor Hobbs for not directing a study, questioning why a governor who professes to care about water would fight an active management area for an "area whose central area is going dry and whose aquifer is over-allocated." A gubernatorial press aide, Christian Slater, did not address questions about directing a study but stated that Governor Hobbs has funded water conservation and recharge measures and collaborated with Mexico through the Arizona-Mexico Commission.