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.
These 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.
By TapWaterData Editorial
Stay Informed About Your Water Quality
Get EPA reports, filter recommendations, and safety alerts for your area.
Join 10,000+ people protecting their families. Unsubscribe anytime.