Arizona committee hears legal differences between irrigation non‑expansion areas and active management areas

Dan Jones, a water lawyer who works with the state’s groundwater programs, told the House Committee on Natural Resources, Energy and Water that Arizona currently uses two groundwater‑management frameworks under the Groundwater Code: irrigation non‑expansion areas (INAs) and active management areas (AMAs).

Jones said INAs are narrower in scope: once an INA is formed, existing irrigated acreage may continue to be farmed but no new acres can be brought into irrigation. “An INA really is pretty straightforward,” Jones said, explaining that INAs are formed where groundwater cannot provide a reasonably safe supply for new irrigation at current withdrawal rates, but where the director does not find it necessary to establish an AMA. INAs can be formed either by decision of the director of the Department of Water Resources (DWR) or by petition and vote of local users.

The committee heard that INA irrigation users who are nonexempt (wells pumping more than 35 gallons per minute or using more than 10 acre‑feet per year for non‑domestic uses) must measure and report withdrawals to DWR using an approved method; there are no general withdrawal fees tied to INAs, Jones said.

By contrast, Jones said AMAs are comprehensive regulatory zones originally created under the 1980 Groundwater Code and expand the state’s toolkit. An AMA may be designated if the director determines active management is necessary to preserve groundwater, if subsidence threatens property/storage, or if groundwater use causes or threatens water‑quality problems. Once an AMA designation process starts, irrigated acreage proposed for inclusion is frozen and no new acreage may be irrigated in that basin.

AMAs require nonexempt users to hold groundwater rights or withdrawal permits, to measure and report withdrawals, and to meet mandatory conservation requirements that are sector‑specific. Jones described several classes of grandfathered groundwater rights that apply inside AMAs: irrigation grandfathered rights (based on historic cropping in the five years before designation), Type 1 and Type 2 non‑irrigation grandfathered rights for conversions or non‑irrigation users, and service‑area rights for public water providers. He said AMAs also include well‑spacing rules, well‑impact analyses for new wells, and a 100‑year assured water‑supply requirement for subdivisions.

On well permits, Jones said DWR’s well‑impact analysis evaluates projected drawdown and other impacts. He cited a rule of thumb used in permitting: if a proposed well’s pumping is projected to increase drawdown by more than 10 feet in the first five years at affected locations, the permit application can fail unless the applicant provides additional hydrologic proof or signed consent from affected neighbors. He also noted depth limits used historically in some AMAs (about 1,000 feet below surface except Pinal at about 1,200 feet) that were part of earlier assured‑supply screening.

Committee members questioned how an individual household’s daily use compares to an acre‑foot and how DWR assesses the 100‑year assured water supply. Jones said household estimates are not his primary area and deferred to other staff for an exact household‑to‑acre‑foot conversion, and he described DWR’s use of regional groundwater flow models to evaluate 100‑year supply rather than simple per‑well depth tests. He said the modern approach examines AMA‑wide impacts using regional models, which are expensive and updated irregularly.

Jones declined to get into all technical details during the committee’s packed agenda but offered to answer follow‑up questions and provide additional materials to members.