countyscore

Best Water Quality Counties in Washington

EPA drinking water health violations and safety grades Compare rankings across all 39 counties.

Average Water Quality Score
59/100
Top County
Asotin County
Counties Ranked
39

Top 10

#1
Asotin County
WA
86/100
#2
Columbia County
WA
86/100
#3
Douglas County
WA
86/100
#4
Jefferson County
WA
86/100
#5
Lincoln County
WA
86/100
#6
Pacific County
WA
86/100
#7
Pend Oreille County
WA
86/100
#8
Snohomish County
WA
86/100
#9
Wahkiakum County
WA
86/100
#10
Whitman County
WA
86/100

All Washington Counties Ranked

#CountyWater Quality ScoreOverall Score
1Asotin County, WA
86
45
2Columbia County, WA
86
44.8
3Douglas County, WA
86
45.1
4Jefferson County, WA
86
48.6
5Lincoln County, WA
86
60.9
6Pacific County, WA
86
45.7
7Pend Oreille County, WA
86
54.7
8Snohomish County, WA
86
41.7
9Wahkiakum County, WA
86
69.1
10Whitman County, WA
86
49.8
11King County, WA
71.1
39.5
12Clark County, WA
69.5
38.2
13Chelan County, WA
68
42
14Kitsap County, WA
67.5
40.1
15Cowlitz County, WA
66.4
36
16Kittitas County, WA
66.4
41.8
17Skagit County, WA
65.3
37.3
18Spokane County, WA
63.8
36.8
19Clallam County, WA
63
40.4
20Yakima County, WA
62.8
30.4
21Mason County, WA
62.2
40.1
22Adams County, WA
60.1
37.4
23Franklin County, WA
58.1
34.4
24Pierce County, WA
57.1
33.7
25Skamania County, WA
54
57.8
26Grays Harbor County, WA
53.6
36.2
27Klickitat County, WA
53.5
52.7
28Walla Walla County, WA
53.3
37
29Thurston County, WA
50.8
37.7
30Lewis County, WA
49.9
37.2
31Okanogan County, WA
49.7
45.9
32Whatcom County, WA
45.3
38
33Grant County, WA
42.5
32.8
34Benton County, WA
41
36.8
35Stevens County, WA
40.7
55.1
36Island County, WA
8.2
50.7
37San Juan County, WA
4.1
55.5
38Garfield County, WA
3.6
54.4
39Ferry County, WA
2
58

Data Source

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