Water quality by county
in Colorado
EPA sampled public water systems across Colorado for PFAS under its UCMR 5 programme. Of the 64 counties, 9 have a reading above a federal limit and 20 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 |
|---|---|---|---|
| Summit County | 30,882 | 5.5× | PFOS · 22 ng/L |
| El Paso County | 752,772 | 4.0× | PFOS · 15.8 ng/L |
| Adams County | 542,973 | 2.6× | PFOS · 10.6 ng/L |
| San Miguel County | 7,819 | 1.9× | PFOS · 7.5 ng/L |
| Douglas County | 393,995 | 1.4× | PFOA · 5.6 ng/L |
| Larimer County | 374,574 | 1.2× | PFOA · 4.8 ng/L |
| Arapahoe County | 666,918 | 1.1× | PFOA · 4.6 ng/L |
| Gunnison County | 17,310 | 1.1× | PFOS · 4.2 ng/L |
| Otero County | 17,991 | 1.0× | PFOS · 4.1 ng/L |
| Prowers County | 11,957 | under the limit | PFHxS · 3.3 ng/L |
| Weld County | 369,745 | under the limit | PFHxS · 3 ng/L |
| Alamosa County | 16,689 | under the limit | — |
| Archuleta County | 14,112 | under the limit | — |
| Baca County | 3,367 | not sampled | — |
| Bent County | 5,779 | not sampled | — |
| Boulder County | 330,262 | under the limit | — |
| Broomfield County | 78,323 | under the limit | — |
| Chaffee County | 20,780 | under the limit | — |
| Cheyenne County | 1,712 | not sampled | — |
| Clear Creek County | 9,076 | under the limit | — |
| Conejos County | 7,549 | under the limit | — |
| Costilla County | 3,686 | not sampled | — |
| Crowley County | 5,600 | not sampled | — |
| Custer County | 5,553 | not sampled | — |
| Delta County | 32,215 | under the limit | — |
| Denver County | 729,019 | under the limit | — |
| Dolores County | 2,467 | not sampled | — |
| Eagle County | 54,330 | under the limit | — |
| Elbert County | 29,382 | not sampled | — |
| Fremont County | 50,093 | under the limit | — |
| Garfield County | 63,167 | under the limit | — |
| Gilpin County | 5,963 | under the limit | — |
| Grand County | 16,154 | under the limit | — |
| Hinsdale County | 747 | not sampled | — |
| Huerfano County | 6,988 | not sampled | — |
| Jackson County | 1,273 | not sampled | — |
| Jefferson County | 578,533 | under the limit | — |
| Kiowa County | 1,392 | not sampled | — |
| Kit Carson County | 7,080 | under the limit | — |
| La Plata County | 56,823 | under the limit | — |
| Lake County | 7,369 | under the limit | — |
| Las Animas County | 14,518 | under the limit | — |
| Lincoln County | 5,598 | under the limit | — |
| Logan County | 20,755 | under the limit | — |
| Mesa County | 161,260 | under the limit | — |
| Mineral County | 933 | under the limit | — |
| Moffat County | 13,142 | under the limit | — |
| Montezuma County | 26,841 | under the limit | — |
| Montrose County | 44,806 | under the limit | — |
| Morgan County | 30,300 | under the limit | — |
| Ouray County | 5,197 | not sampled | — |
| Park County | 18,316 | not sampled | — |
| Phillips County | 4,488 | not sampled | — |
| Pitkin County | 16,643 | under the limit | — |
| Pueblo County | 169,866 | under the limit | — |
| Rio Blanco County | 6,607 | not sampled | — |
| Rio Grande County | 11,132 | under the limit | — |
| Routt County | 25,243 | under the limit | — |
| Saguache County | 6,670 | not sampled | — |
| San Juan County | 821 | not sampled | — |
| Sedgwick County | 2,257 | not sampled | — |
| Teller County | 24,862 | under the limit | — |
| Washington County | 4,771 | not sampled | — |
| Yuma County | 10,048 | under the limit | — |