countyscore

Water Quality · Colorado

Best Water Quality Counties in Colorado 2026

Ranked by EPA drinking water health violations.

Top 10 — Water Quality in Colorado

Score reflects water quality only — not overall county quality.

1Cheyenne County, CO
86
2Crowley County, CO
86
3Custer County, CO
86
4Gilpin County, CO
86
5Hinsdale County, CO
86
6Jackson County, CO
86
7Lake County, CO
86
8Mineral County, CO
86
9San Juan County, CO
86
10Denver County, CO
71.8

All Colorado Counties — Water Quality Rankings

64 counties ranked by water quality score. Overall Score shown for context.

#CountyWater Quality ScoreOverall Score
1Cheyenne County, CO
86
66.3
2Crowley County, CO
86
51.8
3Custer County, CO
86
63.1
4Gilpin County, CO
86
47.9
5Hinsdale County, CO
86
72.1
6Jackson County, CO
86
60.2
7Lake County, CO
86
60.3
8Mineral County, CO
86
69.2
9San Juan County, CO
86
69.1
10Denver County, CO
71.8
33.8
11Arapahoe County, CO
69.8
43
12Mesa County, CO
68
38.5
13Broomfield County, CO
64.6
45.5
14Adams County, CO
60.4
30.4
15Boulder County, CO
56.1
43.4
16Weld County, CO
55.2
38.4
17Montezuma County, CO
54.6
42.4
18Jefferson County, CO
54
40
19Summit County, CO
54
49.6
20Douglas County, CO
52.5
47.8
21Las Animas County, CO
51.8
40.1
22El Paso County, CO
51.3
35.2
23Eagle County, CO
49.9
49.5
24Pitkin County, CO
49.7
57.5
25Moffat County, CO
47.7
42.8
26Larimer County, CO
46.6
40.5
27Grand County, CO
43.5
56
28Yuma County, CO
41.5
55.2
29Fremont County, CO
39.1
45.2
30Lincoln County, CO
37.4
60
31Elbert County, CO
37
60.3
32Chaffee County, CO
36.9
56
33La Plata County, CO
34
45.4
34Saguache County, CO
33.8
58
35Archuleta County, CO
33.3
57.4
36Kit Carson County, CO
33.1
51.7
37Logan County, CO
27.7
38
38Rio Blanco County, CO
27.1
65.1
39Gunnison County, CO
26.5
58.2
40Montrose County, CO
25.8
43
41Rio Grande County, CO
23.9
40.6
42Pueblo County, CO
22.2
32.6
43Morgan County, CO
20.1
37.9
44Washington County, CO
19.7
53.6
45Phillips County, CO
19
59.9
46Routt County, CO
18
54.6
47Conejos County, CO
17.7
64.2
48Sedgwick County, CO
16.3
61.2
49Garfield County, CO
16.2
43.7
50Costilla County, CO
14.2
62.6
51San Miguel County, CO
10.7
64.6
52Clear Creek County, CO
10.3
49.9
53Delta County, CO
10.3
40.8
54Ouray County, CO
8.3
67.3
55Alamosa County, CO
7.2
37
56Park County, CO
7.2
57.7
57Teller County, CO
6.1
51.2
58Dolores County, CO
5.2
60.8
59Huerfano County, CO
4.9
56.6
60Kiowa County, CO
4.3
48.5
61Bent County, CO
2.7
43.1
62Baca County, CO
1.6
63.7
63Prowers County, CO
0.8
54.8
64Otero County, CO
0.5
40.3

Explore More

Best overall counties in ColoradoFull Water Quality data on WaterByCounty