Well water in Grand Isle County, Vermont
In Grand Isle County, <1% of 445 private wells tested had nitrate above the Vermont limit (10 mg/L), according to the Vermont Department of Health.
445 private wells tested in state summaries. Data refreshed September 15, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
An estimated 2,304 people in Grand Isle County get their drinking water from a private well, per USGS 2015 county water use. That is about 34% of residents.
Separately, the USGS national arsenic model estimates that 2% of the 2,304 people on private wells in Grand Isle County draw water above 10 ug/L (the model's range is 1% to 2%), from geology and well depth rather than local tests.
What homeowner tests found
Vermont Tracking private well summaries: private wells tested and reported to the state. Shares are against the level the state applies to each contaminant, named in the last column; several are stricter than EPA. County and state figures combine the town summaries, weighted by wells tested; medians are not combined.
| Contaminant | Above state level | Wells tested | Median | 95th pct | Highest | State level |
|---|---|---|---|---|---|---|
| Gross alpha Gross Alpha | 201 | 23.5 | 15 pCi/L | |||
| Nitrate | 445 | 13.4 | 10 mg/L | |||
| Uranium | 339 | 44 | 20 ug/L | |||
| Fluoride | 377 | 9.74 | 4 mg/L | |||
| Arsenic | 349 | 9 | 10 ug/L |
Closer than the county
See the sampled wells near your address
The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.
Check my addressWhat this means
Among homeowners in Grand Isle County who sent a sample to the state lab, the health-based limits most often exceeded were nitrate (<1% of 445 wells), uranium (<1% of 339 wells), and fluoride (<1% of 377 wells). These are ordinary wells tested by their owners, so the shares are the best available picture of a typical well here, with one caveat: people test more often when they suspect a problem.
What to test for in Grand Isle County
- 1Nitrate<1% of 445 local wells tested were above the Vermont limit.
- 2Uranium<1% of 339 local wells tested were above the Vermont limit.
- 3Fluoride<1% of 377 local wells tested were above the Vermont limit.
- 4Coliform bacteriaRecommended for every private well, every year.
- 5Gross alpha<1% of 201 local wells tested were above the Vermont limit.
- 6Volatile organic compounds (VOCs)49 leaking underground storage tank sites on record locally.
- 7PFAS5 unlined landfills on record locally.
- 8Metals panel9 hazardous waste sites on record locally.
Test your Grand Isle County well for nitrate, uranium and fluoride
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.
Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.
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Where to get a well tested in Vermont: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Grand Isle County numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Grand Isle County
887 domestic wells in Grand Isle County are on record with the state since 1970. 88% are drilled into bedrock, and the typical well is 261 feet deep (one in ten goes past 500 feet).
In a typical Grand Isle County well, bedrock starts about 11 feet down, the median yield is 7 gallons per minute, 24% of wells yield under 3 gallons per minute and usually need a storage tank.
Bedrock wells are where arsenic, uranium and radon come from: the water sits in fractures in granite and metamorphic rock and picks up whatever the rock carries. That is why testing for those three matters more here than in a dug or gravel well.
The rock under Grand Isle County
New York and New England carbonate-rock aquifers
Carbonate-rock. Limestone and dolomite move water through cracks and solution channels, sometimes very fast. Bacteria and nitrate can travel from the surface to a well in days, so annual bacteria testing matters more here than most places; hardness is a given.
Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the county centroid. A single well can sit in a different unit, especially near a boundary.
Official help in Vermont
Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.
- Drinking Water, Vermont Department of Health
- Certification Programs for Other Labs, Vermont Department of Health
Contamination sources on record in Grand Isle County
Vermont ANR records 49 leaking underground storage tank sites, 5 unlined landfills, 9 hazardous waste sites, and 3 reported spills and releases in Grand Isle County, among 98 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.
- 49
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 5
- unlined landfillsOlder unlined landfills are a leading source of PFAS, VOCs and metals in nearby wells.
- 9
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 3
- reported spills and releasesMost spills are fuel; a few are solvents or chemicals that reach the water table.
- 32
- registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
Free, no obligation
Get on the list for a free in-home water test in Grand Isle County
No water treatment company serves Grand Isle County through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Grand Isle County, and you get an email naming it first.
Common questions
How deep are wells in Grand Isle County?
The typical domestic well in Grand Isle County is 261 feet deep, based on 887 wells reported to the state since 1970. One in ten is deeper than 500 feet. 88% are drilled into bedrock.
How often should I test a private well in Grand Isle County?
Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.
Towns in Grand Isle County
Counties near Grand Isle County
Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.
Want the numbers themselves? Download the Vermont dataset as CSV, every county and town, with the sources named.
Sources
- Vermont Tracking private well summaries: summaries for 5 contaminants in Grand Isle County, up to 445 wells each. 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.
- USGS national arsenic model (Ayotte 2017): estimated share of 2,304 people on private wells in Grand Isle County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
- Vermont ANR well completion reports: 926 well records in Grand Isle County, 887 domestic. Well completion reports filed with the Vermont Agency of Natural Resources since 1966. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 3, 2026.
- Vermont ANR regulated sites: 98 regulated sites located in Grand Isle County. Hazardous waste sites, landfills and underground storage tanks from the Vermont Agency of Natural Resources. Retrieved September 3, 2026.
Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.