Mckinley County, New Mexico: drinking water report. McKinley County spans the high desert of northwestern New Mexico, home to Gallup, Zuni Pueblo, Fort…
McKinley County spans the high desert of northwestern New Mexico, home to Gallup, Zuni Pueblo, Fort Defiance, and dozens of rural communities across the Navajo Nation. Water here comes primarily from deep wells tapping the Gallup Sandstone and Dakota aquifers, along with surface water from the San Juan River system. Many rural households rely on unregulated private wells or community water systems that serve fewer than 3,300 people, leaving gaps in monitoring that affect thousands of residents.
This county sits at the intersection of multiple water quality challenges documented across decades. Uranium mining legacy sites dot the landscape, particularly around Church Rock where the 1979 spill released radioactive waste into the Puerco River. While cleanup efforts continue, abandoned mines still contribute uranium, arsenic, and other heavy metals to groundwater in localized areas. The EPA has identified McKinley County as having some of the highest concentrations of unregulated water systems in the Southwest, meaning many residents lack access to routine testing required under the Safe Drinking Water Act.
Arsenic appears naturally in this region's geology and frequently exceeds the 10 parts per billion federal standard in untreated well water. Nitrate contamination from livestock operations and septic systems affects shallow wells, particularly in areas between Gallup and the Arizona border. The city of Gallup's municipal system generally meets federal standards after treatment, but distribution system issues (aging pipes installed in the 1960s and 1970s) create localized lead exposure risks similar to patterns seen across rural New Mexico. Private wells remain unmonitored by federal authorities.
PFAS testing under the EPA's UCMR5 program likely captured only the largest water systems here, missing the majority of small community supplies and all private wells. Nationwide, the Southwest shows lower PFAS detection rates than industrial regions, but McKinley County's proximity to military installations (Fort Wingate Depot) and firefighting training sites suggests potential hotspots that current data may not reflect. Radium and uranium are the persistent natural contaminants of greater documented concern in this geology.
If you rely on a private well or small community system, annual testing for arsenic, uranium, nitrate, and bacteria is essential since no regulatory oversight exists. Municipal water customers should request their utility's consumer confidence report to understand what contaminants appear in treated water and whether lead service lines connect to their property. Check your water for current data specific to your location, review the water filter guide for systems certified to remove arsenic and uranium, read the detailed report for full contaminant information, or visit the New Mexico state page for broader context on water issues affecting the region.
Drinking water is one exposure route. These federal datasets also cover Mckinley County, NM.
The EPA places Mckinley County, NM in Zone 2 - a moderate-risk category, with a predicted average indoor radon level between 2 and 4 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
45% of homes in Mckinley County, NM were built before 1980, and 7% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Mckinley County, NM averages 4.6 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide