Navy expands PFAS testing to private wells near MCAS Yuma

The Navy and Marine Corps are offering expanded PFAS sampling for private drinking-water wells near MCAS Yuma and plan to resample wells tested in 2023. The agencies say PFAS has been detected above their interim action levels in groundwater at the air station. That finding does not establish that nearby private wells are contaminated. The official MCAS Yuma sampling page gives the program details and the results posted so far.

Which wells may qualify

The Navy and Marine Corps are seeking permission to sample private drinking-water wells inside the areas shown on Figure 2 of the official program page. KAWC described the expanded area as extending from La Mesa Linda southwest to Padre Ranchitos and east of Avenue 3E. That broad description cannot determine whether an individual parcel qualifies; residents should check the official map and contact the program. KAWC’s October 5 report provides the local description. The Navy says households served by the City of Yuma’s Main Street or Aqua Viva treatment facilities do not need this private-well sampling.

Private-well owners can ask about eligibility or an appointment by calling 800-374-7843 or emailing [email protected]. The page lists appointments from 8 a.m. to 6 p.m. September 30 through October 7, 2026, with additional times available upon request. As of October 8, it does not give a new cutoff date, so residents should contact the program directly to confirm whether a late appointment can be arranged. Questions can also be sent to [email protected].

Why the sampling area is expanding

NAVFAC says certain PFAS have been detected in groundwater at MCAS Yuma above the Department of War’s interim action levels for private drinking-water wells. The Navy and Marine Corps established sampling areas in the direction groundwater flows from those detections. The original private-well sampling began in May 2023 in an area about one mile downgradient from a known release area. The agencies now say the area should be expanded and that the 2023 wells should be sampled again because laboratory methods have improved. NAVFAC identifies historical use of firefighting foam for testing, training, firefighting and emergency response as the most common activity that could have released PFAS at the air station.

The thresholds are different for private and public wells

The September 2026 Navy fact sheet lists DoW interim action levels for private wells of 12 parts per trillion (ppt) for PFOA and PFOS, and 30 ppt for PFNA, PFHxS and GenX (HFPO-DA). For a mixture containing at least two of PFHxS, PFNA, HFPO-DA and PFBS, the listed hazard-index action level is 3. The same table lists EPA drinking-water standards for public systems separately: 4 ppt for PFOA and PFOS, 10 ppt for PFNA, PFHxS and GenX, and a hazard index of 1. The standards for public systems and DoW’s action levels for private wells are not interchangeable. NAVFAC says it will review and update DoW policy if EPA changes applicable requirements. Read the September 2026 fact sheet

What the existing results show

The latest results posted on the program page are from five private wells sampled in 2023. The Navy reports that one had no PFAS detections, four had detections below the current DoW interim action levels, and none had detections at or above those levels. The published table says its sample numbers do not identify specific properties. These five results do not establish the condition of other wells in the expanded area.

No 2026 private-well results were posted on the Navy page as of October 8. The agencies say preliminary results are expected about 30 days after collection. After independent third-party quality review, validated results are expected to be provided to property owners and tenants about three months after sampling.

What happens if a well exceeds an action level

The Navy and Marine Corps say they will address private-well PFAS at or above DoW interim action levels under department policy and work with property owners on a longer-term solution. Options listed by NAVFAC include connecting a property to public water or installing a drinking-water treatment system. For wells with PFOA or PFOS individually or combined above 70 ppt, the agencies say they can provide bottled water for drinking and cooking until a longer-term solution is in place. Final remedial actions are to address drinking-water wells to EPA public-system standards or background levels under the federal cleanup process.

A separate local PFAS question

YumaInformed’s existing PFAS and biosolids explainer covers a separate set of research and local questions. The MCAS Yuma sampling materials reviewed for this story do not establish a connection between PFAS at the air station and AgTech biosolids. The Navy’s program is focused on groundwater findings at MCAS Yuma and testing private wells in the mapped study areas.