Water quality by county
in Wisconsin
EPA sampled public water systems across Wisconsin for PFAS under its UCMR 5 programme. Of the 72 counties, 18 have a reading above a federal limit and 17 have not been sampled at all — which is not a clean result, only an absence of one. Each county below shows what was found, at what concentration, and at which utility.
| county | Population | Worst result | Compound |
|---|---|---|---|
| Ozaukee County | 93,956 | 7.8× | PFOS · 31 ng/L |
| Waukesha County | 417,029 | 6.9× | PFHxS · 69 ng/L |
| Lincoln County | 28,461 | 5.3× | PFOA · 21 ng/L |
| Washington County | 138,727 | 3.8× | PFOA · 15 ng/L |
| Wood County | 73,943 | 3.5× | PFOS · 14 ng/L |
| Marathon County | 139,091 | 3.3× | PFOS · 13 ng/L |
| Crawford County | 16,008 | 2.8× | PFOS · 11 ng/L |
| Pierce County | 43,380 | 2.5× | PFOA · 9.9 ng/L |
| Sawyer County | 18,835 | 2.1× | PFOA · 8.5 ng/L |
| Oneida County | 38,175 | 1.7× | PFOA · 6.8 ng/L |
| Jefferson County | 86,245 | 1.6× | PFOS · 6.2 ng/L |
| La Crosse County | 121,060 | 1.4× | PFOS · 5.5 ng/L |
| Door County | 30,512 | 1.3× | PFHxS · 13 ng/L |
| Sheboygan County | 118,331 | 1.2× | PFHxS · 12 ng/L |
| Walworth County | 106,029 | 1.2× | PFOA · 4.7 ng/L |
| Eau Claire County | 108,830 | 1.1× | PFHxS · 11 ng/L |
| Waupaca County | 51,171 | 1.1× | PFOS · 4.3 ng/L |
| Taylor County | 20,167 | 1.0× | PFOA · 4.1 ng/L |
| Columbia County | 58,113 | under the limit | PFHxS · 8.1 ng/L |
| Dane County | 588,347 | under the limit | PFHxS · 7.3 ng/L |
| Monroe County | 46,370 | under the limit | PFHxS · 5.7 ng/L |
| Sauk County | 66,486 | under the limit | PFHxS · 4.4 ng/L |
| Adams County | 21,352 | not sampled | — |
| Ashland County | 16,196 | under the limit | — |
| Barron County | 46,810 | under the limit | — |
| Bayfield County | 16,838 | under the limit | — |
| Brown County | 273,909 | under the limit | — |
| Buffalo County | 13,464 | not sampled | — |
| Burnett County | 17,187 | not sampled | — |
| Calumet County | 53,602 | under the limit | — |
| Chippewa County | 67,323 | under the limit | — |
| Clark County | 34,801 | not sampled | — |
| Dodge County | 88,635 | under the limit | — |
| Douglas County | 44,276 | under the limit | — |
| Dunn County | 46,135 | under the limit | — |
| Florence County | 4,673 | not sampled | — |
| Fond du Lac County | 104,269 | under the limit | — |
| Forest County | 9,506 | not sampled | — |
| Grant County | 52,330 | under the limit | — |
| Green County | 37,183 | under the limit | — |
| Green Lake County | 19,370 | under the limit | — |
| Iowa County | 23,963 | under the limit | — |
| Iron County | 6,235 | not sampled | — |
| Jackson County | 21,027 | under the limit | — |
| Juneau County | 26,590 | under the limit | — |
| Kenosha County | 168,754 | under the limit | — |
| Kewaunee County | 20,751 | not sampled | — |
| Lafayette County | 17,306 | under the limit | — |
| Langlade County | 19,535 | under the limit | — |
| Manitowoc County | 81,513 | under the limit | — |
| Marinette County | 42,343 | under the limit | — |
| Marquette County | 15,743 | not sampled | — |
| Menominee County | 4,286 | not sampled | — |
| Milwaukee County | 924,740 | under the limit | — |
| Oconto County | 40,037 | under the limit | — |
| Outagamie County | 195,390 | under the limit | — |
| Pepin County | 7,555 | under the limit | — |
| Polk County | 45,831 | not sampled | — |
| Portage County | 72,040 | under the limit | — |
| Price County | 14,087 | not sampled | — |
| Racine County | 198,651 | under the limit | — |
| Richland County | 17,123 | under the limit | — |
| Rock County | 165,461 | under the limit | — |
| Rusk County | 14,168 | not sampled | — |
| Shawano County | 41,299 | under the limit | — |
| St. Croix County | 97,954 | under the limit | — |
| Trempealeau County | 30,801 | not sampled | — |
| Vernon County | 31,351 | under the limit | — |
| Vilas County | 23,948 | not sampled | — |
| Washburn County | 16,982 | not sampled | — |
| Waushara County | 25,079 | not sampled | — |
| Winnebago County | 173,307 | under the limit | — |