Private Well Water Testing in Oregon
County-by-county USGS area-risk estimates for private wells across Oregon — arsenic exceedance probability and private-well population — plus how to test your own well at a Oregon-certified laboratory.
Oregon private-well risk summary
Counties covered
36
Oregon counties with modeled risk data.
People on private wells
area estimate521,584
estimated across covered Oregon counties.
Average arsenic risk
area estimate7%
average modeled chance a well exceeds 10 µg/L arsenic across covered counties.
Oregon counties
- Clackamas County3% arsenic exceedance (area estimate)56,315 people on private wells
- Lane County4% arsenic exceedance (area estimate)55,479 people on private wells
- Marion County4% arsenic exceedance (area estimate)47,623 people on private wells
- Jackson County4% arsenic exceedance (area estimate)44,699 people on private wells
- Linn County3% arsenic exceedance (area estimate)41,834 people on private wells
- Josephine County3% arsenic exceedance (area estimate)37,949 people on private wells
- Washington County16% arsenic exceedance (area estimate)22,145 people on private wells
- Deschutes County5% arsenic exceedance (area estimate)21,859 people on private wells
- Douglas County3% arsenic exceedance (area estimate)20,617 people on private wells
- Umatilla County14% arsenic exceedance (area estimate)18,834 people on private wells
- Klamath County8% arsenic exceedance (area estimate)18,265 people on private wells
- Yamhill County8% arsenic exceedance (area estimate)16,710 people on private wells
- Benton County2% arsenic exceedance (area estimate)16,167 people on private wells
- Malheur County21% arsenic exceedance (area estimate)13,204 people on private wells
- Columbia County4% arsenic exceedance (area estimate)12,241 people on private wells
- Coos County3% arsenic exceedance (area estimate)11,084 people on private wells
- Crook County7% arsenic exceedance (area estimate)9,705 people on private wells
- Multnomah County4% arsenic exceedance (area estimate)6,822 people on private wells
- Union County7% arsenic exceedance (area estimate)5,905 people on private wells
- Polk County3% arsenic exceedance (area estimate)5,715 people on private wells
- Lincoln County3% arsenic exceedance (area estimate)4,435 people on private wells
- Wasco County6% arsenic exceedance (area estimate)4,060 people on private wells
- Curry County2% arsenic exceedance (area estimate)3,990 people on private wells
- Lake County11% arsenic exceedance (area estimate)3,980 people on private wells
- Morrow County18% arsenic exceedance (area estimate)3,783 people on private wells
- Baker County6% arsenic exceedance (area estimate)3,521 people on private wells
- Harney County13% arsenic exceedance (area estimate)2,540 people on private wells
- Wallowa County5% arsenic exceedance (area estimate)2,378 people on private wells
- Tillamook County2% arsenic exceedance (area estimate)2,279 people on private wells
- Jefferson County9% arsenic exceedance (area estimate)2,032 people on private wells
- Clatsop County3% arsenic exceedance (area estimate)1,738 people on private wells
- Grant County5% arsenic exceedance (area estimate)1,612 people on private wells
- Hood River County3% arsenic exceedance (area estimate)650 people on private wells
- Gilliam County19% arsenic exceedance (area estimate)549 people on private wells
- Sherman County19% arsenic exceedance (area estimate)532 people on private wells
- Wheeler County7% arsenic exceedance (area estimate)333 people on private wells
Find a Oregon-certified testing lab
Get your well tested at a Oregon-certified laboratory. We list certification programs by state.
Already tested your well? Get a free plain-English reading
Upload your well water lab report (PDF or a photo) and our team will email you a full, plain-English reading of every result — free. Educational only, never medical advice.
Your upload also helps us keep local water data accurate — we only ever share anonymized, area-level summaries.
Upload my well testThese figures are USGS area estimates: statistical groundwater models describing how likely elevated contaminant levels are across a county. They are not designed to predict the concentration in any single well. Only testing your own well reveals its water quality.
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