St. Lawrence County Water Quality

St. Lawrence County, New York has a drinking-water quality grade of B with a score of 68.6/100, based on EPA SDWIS compliance data. The county has 1 health-based drinking water violation over the past 5 years. Watershed health, monitoring records, and live streamflow are reported separately on this page.

St. Lawrence County has 1 health-based drinking water violation recorded by the EPA over the past 5 years. Health-based violations indicate instances where contaminant levels exceeded EPA Maximum Contaminant Levels (MCLs). Violations may have been resolved — check with your local water utility for current status.

EPA's Water Quality Portal records 74,002 measurements from 46 monitoring sites in St. Lawrence County over the past five years. The most frequently measured characteristic groups are Physical, Organics, Pesticide, Organics, Other. Each measurement is a single sample analyzed for one characteristic (E. coli, pH, dissolved oxygen, etc.). High monitoring density means more scientific evidence behind any reported signal — it does not by itself indicate water quality.

St. Lawrence County's SDWIS water quality score of 68.6/100 is higher than the New York state average of 40.1. The average water quality grade across New York is D, based on data from 57 counties with available SDWIS data.

Based on EPA SDWIS data, St. Lawrence County has a water quality grade of B (68.6/100). 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).

St. Lawrence County has 1 health-based drinking water violation according to EPA records. With a water quality score of 68.6/100 and grade B, the county's drinking water has had some compliance issues but continues to be monitored. 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.

St. Lawrence County ranks #7 out of 57 counties in New York by SDWIS water quality score (1 = best). With a score of 68.6/100, 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.