Correction: This article was corrected to remove a misleading quote, add an accurate reflection of the number of public comments provided to the ADWR and clarify that only new groundwater expansion is suspended in the Ranegras Plain while it is under consideration for an Active Management Area designation. Further clarity was also added through the addition of groundwater statute. We apologize for the errors.

Key Points:

• The Ranegras Plain Groundwater Basin could be designated an active management area
• The deadline for the ADWR to decide on the Ranegras Plain becoming an active management area is Jan. 17
• Agricultural pumping in the Ranegras Plain basin has averaged about 40,000 acre-feet per year since 2016

The Arizona Department of Water Resources is currently moving forward with a process to legally regulate groundwater pumping in the Ranegras Plain. 

The ADWR is examining the Ranegras Plain groundwater basin to designate it as the next Active Management Area, which would give it the ability to control the amount of water being pumped. A public hearing on Dec. 18 will be the next step toward finalizing the Ranegras Plain’s AMA status, according to an ADWR spokesperson.

“It is significant that we are seeing groundwater subsidence in that basin. We are seeing severe groundwater overdraft,” said Ben Bryce, the special adviser to the director at the ADWR. “Much more water is coming out of the groundwater basin than is going in.”

An area with heavy reliance on mined groundwater is usually subject to becoming an AMA. If it does become one, the state will regulate water based on that area’s specific conditions. 

Located in both Yuma and La Paz Counties, the Ranegras Plain Groundwater Basin covers 912 square miles and has a sparse, widespread population. According to an ADWR memorandum on the basin, United States Geological Survey data from 2022 says agricultural pumping in the Ranegras Plain basin has averaged an unsustainable 40,000 acre-feet per year since 2016. 

On Nov. 5, ADWR instituted a prohibition on new irrigation systems in the Ranegras Plain basin to limit groundwater loss before the possible AMA designation. The department has until Jan. 17 — 30 days after its Dec. 18 public hearing — to decide on the future of the Ranegras Plain’s groundwater usage. 

If the ADWR director ultimately decides against an AMA, then irrigation will go back to normal without further regulation. If it decides to make the Ranegras Plain an AMA, the prohibition on irrigation expansion will continue, and the ADWR will work to develop a groundwater goal and management plan, Bryce said. 

“The Ranegras Plain Basin has been experiencing significant groundwater level declines since the 1940s. The rate of decline has increased over time,” the Ranegras Plain memorandum from ADWR reads. “As the widespread decline in water levels indicates, the aquifer system’s outflows far exceed its inflows.”

Bryce specifically mentioned agricultural pumping uses the most groundwater, but if the area were designated an AMA it would see regulation on all non-exempt wells whether they are agricultural, industrial or municipal.  

Areas under consideration for an AMA must meet one of three requirements to qualify, as spelled out in statute: (1) Active management practices are necessary to preserve the existing supply of groundwater for future needs; (2) Land subsidence or fissuring is endangering property or potential groundwater storage capacity; or (3) Use of groundwater is resulting in actual or threatened water quality degradation. 

After the announcement of the ADWR’s decision to move forward with the AMA process for the Ranegras plain, they were met with dozens of public comments concerning the regulation of groundwater, with many saying unregulated pumping is necessary for business and farming in the area. 

Bryce also said he understands the people’s requests, as rural areas may be less used to government regulations. 

“There’s plenty of folks out there who aren’t sure what something like this looks like, and want to be informed,” Bryce said. “So we’ve been trying to be responsive when we can be and responding to emails and to questions that folks have presented to us.”