countyscore

Best Water Quality Counties in Oregon

EPA drinking water health violations and safety grades Compare rankings across all 36 counties.

Average Water Quality Score
45/100
Top County
Gilliam County
Counties Ranked
36

Top 10

#1
Gilliam County
OR
86/100
#2
Harney County
OR
86/100
#3
Jefferson County
OR
86/100
#4
Sherman County
OR
86/100
#5
Union County
OR
86/100
#6
Wallowa County
OR
86/100
#7
Wheeler County
OR
86/100
#8
Washington County
OR
68/100
#9
Multnomah County
OR
67/100
#10
Deschutes County
OR
60/100

All Oregon Counties Ranked

#CountyWater Quality ScoreOverall Score
1Gilliam County, OR
86
44.9
2Harney County, OR
86
55.6
3Jefferson County, OR
86
48.1
4Sherman County, OR
86
55.3
5Union County, OR
86
43.2
6Wallowa County, OR
86
63.9
7Wheeler County, OR
86
55.3
8Washington County, OR
67.7
41.2
9Multnomah County, OR
66.8
44.4
10Deschutes County, OR
60.1
44.3
11Linn County, OR
53.8
35
12Marion County, OR
50.4
30.4
13Klamath County, OR
50.1
36.7
14Hood River County, OR
49.3
48.2
15Umatilla County, OR
45.9
33.2
16Polk County, OR
45.5
43.3
17Lake County, OR
42.7
65.3
18Clackamas County, OR
37.6
36.5
19Crook County, OR
35
48.1
20Yamhill County, OR
34
40.9
21Morrow County, OR
33.9
45.1
22Clatsop County, OR
32.7
37.4
23Grant County, OR
29.4
64.1
24Lane County, OR
29
30.8
25Douglas County, OR
28.5
36.8
26Baker County, OR
28.4
36.3
27Lincoln County, OR
27.8
34.2
28Tillamook County, OR
27.3
43.5
29Benton County, OR
21.6
35.8
30Jackson County, OR
19.6
31.5
31Josephine County, OR
16.9
35.7
32Wasco County, OR
15.9
32.3
33Coos County, OR
14
29.2
34Columbia County, OR
13.9
43
35Curry County, OR
13.9
41.9
36Malheur County, OR
11.4
37.8

Data Source

Water Quality data from WaterByCounty. See full details at WaterByCounty. Data updated February 2026.