Nitrate in Vermont well water
In Vermont, <1% of 22,502 private wells tested had nitrate above the Vermont limit (10 mg/L), according to the Vermont Department of Health.
Nitrate reaches wells from fertilizer, septic systems and manure. Above the limit it can cause methemoglobinemia (blue baby syndrome) in infants under six months, and long-term exposure is associated with some cancers. Shallow and dug wells near farmland or dense septic systems are most at risk.
By county, from homeowner tests
Share of private wells above the state guidance level (10 mg/L) in tests homeowners sent to the state lab, to .
| County | Wells tested | Above state level | Highest | |
|---|---|---|---|---|
| Franklin | 3,060 | <1% | 19 mg/L | |
| Washington | 2,979 | <1% | 26 mg/L | |
| Addison | 2,022 | <1% | 17 mg/L | |
| Caledonia | 960 | <1% | 15 mg/L | |
| Orleans | 1,306 | <1% | 32.8 mg/L | |
| Grand Isle | 445 | <1% | 13.4 mg/L | |
| Windham | 1,044 | <1% | 27.6 mg/L | |
| Chittenden | 4,814 | <1% | 51.5 mg/L | |
| Orange | 1,032 | <1% | 33.1 mg/L | |
| Windsor | 1,239 | <1% | 15 mg/L | |
| Lamoille | 1,924 | <1% | 11.6 mg/L | |
| Rutland | 993 | <1% | 13.1 mg/L | |
| Bennington | 515 | 0% | 7.8 mg/L | |
| Essex | 169 | 0% | 7 mg/L |
Towns with the highest share above the state level
- Montpelier, Washington County8% of 66 wells
- Berkshire, Franklin County5% of 150 wells
- Dummerston, Windham County4% of 68 wells
- Bristol, Addison County4% of 187 wells
- Woodbury, Washington County3% of 87 wells
- East Montpelier, Washington County3% of 262 wells
- Salisbury, Addison County3% of 113 wells
- Bolton, Chittenden County3% of 112 wells
- Sheldon, Franklin County3% of 152 wells
- Enosburgh, Franklin County2% of 126 wells
- Franklin, Franklin County2% of 130 wells
- Hartford, Windsor County2% of 93 wells
- Glover, Orleans County2% of 91 wells
- Derby, Orleans County2% of 146 wells
- Underhill, Chittenden County2% of 374 wells
- Hyde Park, Lamoille County2% of 156 wells
- Williamstown, Orange County2% of 112 wells
- Hardwick, Caledonia County2% of 109 wells
- Lyndon, Caledonia County2% of 62 wells
- Groton, Caledonia County2% of 61 wells
- Alburgh, Grand Isle County2% of 133 wells
- St. Johnsbury, Caledonia County1% of 69 wells
- Highgate, Franklin County1% of 315 wells
- Pawlet, Rutland County1% of 75 wells
- Barre, Washington County1% of 198 wells
By county, from individual samples
Public monitoring samples against the EPA limit (10 mg/L); counties with at least 30 samples.
Sources
- Vermont Tracking private well summaries: Town summaries of private well tests reported to the Vermont Department of Health, published through Vermont Environmental Public Health Tracking. Shares are against the limit Vermont applies to each analyte: arsenic 10 ug/L, uranium 20 ug/L (stricter than EPA), fluoride 4 mg/L, nitrate 10 mg/L, gross alpha 15 pCi/L, radon 4,000 pCi/L advisory. Only towns with 20 or more results are published; statistics below the reporting limit show as *. Retrieved September 3, 2026.
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. nitrate counts and shares are listed on each county and town page with their sources.