Water Quality · Oregon
Best Water Quality Counties in Oregon 2026
Ranked by EPA drinking water health violations.
Top 10 — Water Quality in Oregon
Score reflects water quality only — not overall county quality.
All Oregon Counties — Water Quality Rankings
36 counties ranked by water quality score. Overall Score shown for context.
| # | County | Water Quality Score | Overall Score |
|---|---|---|---|
| 1 | Gilliam County, OR | 86 | 44.9 |
| 2 | Harney County, OR | 86 | 55.5 |
| 3 | Jefferson County, OR | 86 | 48.1 |
| 4 | Sherman County, OR | 86 | 55.3 |
| 5 | Union County, OR | 86 | 43.2 |
| 6 | Wallowa County, OR | 86 | 63.9 |
| 7 | Wheeler County, OR | 86 | 55.3 |
| 8 | Washington County, OR | 67.7 | 41.2 |
| 9 | Multnomah County, OR | 66.8 | 44.4 |
| 10 | Deschutes County, OR | 60.1 | 44.3 |
| 11 | Linn County, OR | 53.8 | 35 |
| 12 | Marion County, OR | 50.4 | 30.4 |
| 13 | Klamath County, OR | 50.1 | 36.7 |
| 14 | Hood River County, OR | 49.3 | 48.2 |
| 15 | Umatilla County, OR | 45.9 | 33.1 |
| 16 | Polk County, OR | 45.5 | 43.3 |
| 17 | Lake County, OR | 42.7 | 65.3 |
| 18 | Clackamas County, OR | 37.6 | 36.5 |
| 19 | Crook County, OR | 35 | 48 |
| 20 | Yamhill County, OR | 34 | 40.9 |
| 21 | Morrow County, OR | 33.9 | 45.1 |
| 22 | Clatsop County, OR | 32.7 | 37.4 |
| 23 | Grant County, OR | 29.4 | 64.1 |
| 24 | Lane County, OR | 29 | 30.8 |
| 25 | Douglas County, OR | 28.5 | 36.8 |
| 26 | Baker County, OR | 28.4 | 36.2 |
| 27 | Lincoln County, OR | 27.8 | 34.2 |
| 28 | Tillamook County, OR | 27.3 | 43.5 |
| 29 | Benton County, OR | 21.6 | 35.8 |
| 30 | Jackson County, OR | 19.6 | 31.4 |
| 31 | Josephine County, OR | 16.9 | 35.7 |
| 32 | Wasco County, OR | 15.9 | 32.3 |
| 33 | Coos County, OR | 14 | 29.2 |
| 34 | Columbia County, OR | 13.9 | 43 |
| 35 | Curry County, OR | 13.9 | 41.9 |
| 36 | Malheur County, OR | 11.4 | 37.8 |