PFOS in Maine well water
In Maine, 11% of 3,567 tested private well samples exceeded the EPA limit for PFOS (4 ng/L).
PFOS is a forever chemical with the same sources as PFOA. It is linked to immune suppression, thyroid disease, liver effects and cancer. Wells near airports, fire training areas, landfills and plating plants are most at risk.
By county, from individual samples
Public monitoring samples against the EPA limit (4 ng/L); counties with at least 30 samples.
| County | Samples | Detected | Above EPA limit | Median | Highest |
|---|---|---|---|---|---|
| Somerset | 576 | 56% | 28% | 0.804 | 17,200 ng/L |
| Lincoln | 110 | 52% | 15% | 0.504 | 64.3 ng/L |
| Washington | 36 | 31% | 14% | 0 | 51 ng/L |
| Aroostook | 113 | 35% | 12% | 0 | 32.5 ng/L |
| Kennebec | 450 | 48% | 12% | 0 | 101 ng/L |
| Knox | 36 | 44% | 11% | 0 | 31.3 ng/L |
| Penobscot | 294 | 41% | 10% | 0 | 96 ng/L |
| Cumberland | 574 | 51% | 9% | 0.485 | 91.8 ng/L |
| York | 386 | 48% | 6% | 0 | 30.6 ng/L |
| Waldo | 401 | 33% | 6% | 0 | 668 ng/L |
| Androscoggin | 215 | 35% | 6% | 0 | 64.1 ng/L |
| Hancock | 58 | 36% | 5% | 0 | 18 ng/L |
| Franklin | 44 | 25% | 5% | 0 | 14.8 ng/L |
| Oxford | 73 | 25% | 4% | 0 | 5.28 ng/L |
| Piscataquis | 30 | 23% | 3% | 0 | 4.84 ng/L |
- Fairfield, Somerset County32% of 466
- Damariscotta, Lincoln County29% of 35
- Benton, Kennebec County29% of 56
- Sidney, Kennebec County26% of 43
- Chelsea, Kennebec County13% of 46
- North Yarmouth, Cumberland County13% of 46
- Windham, Cumberland County13% of 40
- Falmouth, Cumberland County13% of 72
- Vassalboro, Kennebec County12% of 34
- Sabattus, Androscoggin County12% of 34
- Unity, Waldo County10% of 89
- Buxton, York County10% of 60
- Gray, Cumberland County10% of 31
- Pownal, Cumberland County10% of 52
- Brewer, Penobscot County9% of 33
- Corinna, Penobscot County9% of 44
- Arundel, York County8% of 36
- Wells, York County8% of 63
- Gorham, Cumberland County8% of 79
- Dayton, York County7% of 56
Sources
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. PFOS counts and shares are listed on each county and town page with their sources.