Your county health department
Oregon doesn't run a statewide free testing program that we know of. Some county health departments test wells or sell kits, so call yours first.
Oregon's private well pageNitrate in Oregon well water, by county
Nitrate is widespread, over the limit in 15% or more of tested wells, in 4 of the 29 Oregon counties with 10 or more tested wells. 1 more look high, but those results likely overstate it. A county's share tells you how likely a problem is nearby. Only a test of your own well tells you what's in it.
How Oregon compares with the rest of the country
Across Oregon, about 1 in 9 tested wells had nitrate over the EPA limit of 10 mg/L (341 of 3,072). Across all tested wells in the US it's about 1 in 12. So nitrate turns up somewhat more often in Oregon than in the country as a whole. Check your county below.
Why it matters: It's dangerous for babies under 6 months, because it keeps their blood from carrying enough oxygen.
Nitrate soaks down into groundwater from fertilizer, manure and septic systems.
Nitrate in tested wells, county by county
Share of each county's tested wells with at least one result over the EPA limit of 10 mg/L. Counties need 10 or more tested wells to be listed. Widespread means 15% or more, worth checking 5 to 15%, rare under 5%.
| County | Wells tested | Wells over the limit | Level |
|---|---|---|---|
| Malheur County | 49 | Widespread | |
| Morrow County | 121 | Widespread | |
| Union County | 16 | Widespread | |
| Umatilla County | 272 | Widespread | |
| Lane County | 273 | Widespread | |
| Benton County | 135 | Worth checking | |
| Deschutes County | 557 | Worth checking | |
| Curry County | 12 | Worth checking | |
| Linn County | 346 | Worth checking | |
| Jackson County | 168 | Rare | |
| Multnomah County | 46 | Rare | |
| Lincoln County | 27 | Rare | |
| Clatsop County | 82 | Rare | |
| Washington County | 30 | Rare | |
| Klamath County | 201 | Rare | |
| Marion County | 90 | Rare | |
| Douglas County | 159 | Rare | |
| Harney County | 153 | Rare | |
| Yamhill County | 69 | Rare | |
| Tillamook County | 40 | Rare | |
| Josephine County | 37 | Rare | |
| Clackamas County | 36 | Rare | |
| Wasco County | 35 | Rare | |
| Coos County | 28 | Rare | |
| Polk County | 21 | Rare | |
| Columbia County | 14 | Rare | |
| Lake County | 13 | Rare | |
| Gilliam County | 12 | Rare | |
| Crook County | 11 | Rare |
* Likely overstated. These shares come from a narrow set of wells, so they probably run high for the county as a whole:
- Malheur County: All of these tests come from Oregon's environment department in one small part of the county, so this likely overstates it.
6 more Oregon counties have 1 to 9 tested wells for nitrate, too few to rate.
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Where to get your well tested for nitrate in Oregon
A lab Oregon certifies
Ask for nitrate by name. Results from a certified lab count for a home sale or a loan.
Labs certified by OregonA mail-in kit
Fill the bottles at your kitchen tap and mail them back. We mark the kits that include nitrate.
Compare kitsKeep reading about wells in Oregon
- Well water testing in Oregon: how to get tested and what turns up statewide
- Nitrate in well water: where it comes from, what it does and how to remove it
- Arsenic in Oregon wells, by county
- Uranium in Oregon wells, by county
- Manganese in Oregon wells, by county
- Lead in Oregon wells, by county
Questions people ask about nitrate in Oregon
Is there nitrate in Oregon well water?
Nitrate is widespread, over the limit in 15% or more of tested wells, in 4 of the 29 Oregon counties with 10 or more tested wells. 1 more look high, but those results likely overstate it. Across Oregon, about 1 in 9 tested wells had nitrate over the EPA limit of 10 mg/L (341 of 3,072). Across all tested wells in the US it's about 1 in 12. So nitrate turns up somewhat more often in Oregon than in the country as a whole. Check your county below.
Where can I get my well tested for nitrate in Oregon?
Use a lab certified by Oregon for drinking water, or a mail-in kit that includes nitrate from a certified lab. Some county health departments test wells too, so call yours first.
See Oregon's list of certified labs, or compare mail-in kits.
Where these numbers come from
- Lab tests: Water Quality Portal (USGS and EPA), well samples since 2000. A well counts as over if any of its tests was over the EPA limit of 10 mg/L. Wells tested for studies and monitoring, not a random sample of homes.
- Likely overstated: our own check of who tested the wells, when and where. How we check.
- State programs and links: Oregon Health Authority.