Los Alamos County Water Quality

Los Alamos County, New Mexico has a drinking-water quality grade of A with a score of 86.0/100, based on EPA SDWIS compliance data. The county has 0 health-based drinking water violations over the past 5 years. Watershed health, monitoring records, and live streamflow are reported separately on this page.

Los Alamos County has 0 health-based drinking water violations recorded by the EPA over the past 5 years. Health-based violations indicate instances where contaminant levels exceeded EPA Maximum Contaminant Levels (MCLs). Zero violations is an excellent record indicating consistent compliance with federal drinking water standards.

EPA ATTAINS assessments under Clean Water Act §303(d) indicate 35.7% of Los Alamos County's 115 assessed water bodies are classified as impaired (41 impaired). The top reported causes are POLYCHLORINATED BIPHENYLS (PCBS), ALPHA PARTICLES, ALUMINUM, TOTAL. Impairment means the water body fails to meet state quality standards for at least one designated use — drinking water source, recreation, aquatic life, or fish consumption. Note: watershed impairment doesn't always translate to tap-water issues; treatment plants can remove most regulated contaminants.

Los Alamos County's SDWIS water quality score of 86.0/100 is higher than the New Mexico state average of 21.7. The average water quality grade across New Mexico is F, based on data from 32 counties with available SDWIS data.

Based on EPA SDWIS data, Los Alamos County has a water quality grade of A (86.0/100). This indicates good to excellent water quality with strong SDWIS compliance. The grade speaks to the public water system, not the watershed — for watershed-level concerns, see the Watershed Health zone. For the most up-to-date information, contact your local water utility or review your Consumer Confidence Report (CCR).

Los Alamos County has 0 health-based drinking water violations according to EPA records. With a water quality score of 86.0/100 and grade A, the county's drinking water meets EPA standards with no recorded health violations. Note: drinking-water compliance speaks to the public water system, not necessarily to the watershed itself — check the Watershed Health zone for ATTAINS §303(d) data.

Los Alamos County ranks #2 out of 32 counties in New Mexico by SDWIS water quality score (1 = best). With a score of 86.0/100, it falls in the top third of counties statewide. The ranking reflects EPA SDWIS compliance only — not watershed impairment, monitoring density, or streamflow, which are tracked separately on this page.