Grand Isle County Water Quality

Grand Isle County, Vermont has a drinking-water quality grade of C with a score of 51.8/100, 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.

Grand Isle 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 469 measurements from 8 monitoring sites in Grand Isle County over the past five years. The most frequently measured characteristic groups are Nutrient, Biological, Algae, Phytoplankton, Physical. 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.

Grand Isle County's SDWIS water quality score of 51.8/100 is higher than the Vermont state average of 45.6. The average water quality grade across Vermont is D, based on data from 14 counties with available SDWIS data.

Based on EPA SDWIS data, Grand Isle County has a water quality grade of C (51.8/100). This indicates moderate compliance. Some violations have been recorded but overall standards are maintained. 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).

Grand Isle County has 1 health-based drinking water violation according to EPA records. With a water quality score of 51.8/100 and grade C, 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.

Grand Isle County ranks #4 out of 14 counties in Vermont by SDWIS water quality score (1 = best). With a score of 51.8/100, 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.