Manganese is widespread in Linn County wells.
1 widespread, 1 worth checking, 4 rare out of 6 health checks.
From 352 wells tested in Linn County since 2000; your own well needs its own test. How to read this
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
1 in 3 people 51,436 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
How deep wells go here
Middle depth: some shelter from the surface, not complete.
Well depths: US Groundwater Well Database
Radon risk (a gas from rock)
Less likely, but the EPA still says test your air.
Radon zones: EPA map
Here's how Linn County compares with Oregon and the counties around it.
Each result puts Linn County next to the 6 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in Linn County wells.
Manganese9 of 52 wells over
Too few tested to show: Jefferson.
This one is worth checking in Linn County.
Nitrate22 of 346 wells over
Too few tested to show: Jefferson.
These 4 are rare in Linn County.
Lead2 of 50 wells over
Too few tested to show: Jefferson.
Arsenic0 of 45 wells over
Too few tested to show: Jefferson.
Uranium0 of 19 wells over
Too few tested to show: Jefferson.
Fluoride0 of 10 wells over
Too few tested to show: Benton, Jefferson, Lane, Marion, Polk.
Coliform bacteria turned up in 4 of 23 tested Linn County wells, so test for it every year.
Coliform bacteria4 of 23 wells had it
Too few tested to show: Jefferson.
E. coli1 of 24 wells had it
Too few tested to show: Jefferson.
E. coli means human or animal waste is getting in, so if a test of your Linn County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 15 of 51 tested wells, and it isn't a health risk.
Iron stains15 of 51 wells had it
Too few tested to show: Jefferson.
Most of the 352 wells tested in Linn County were last tested before 2010.
An old result shows the water as it was then, so treat these 352 wells as a starting point and test your own.
Most Linn County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).
One mail-in lab test covers the 4 things to check in Linn County.
- Bacteria
- Nitrate
- Manganese
- Arsenic
What Oregon offers well owners
- Free testingWe didn't find a free program for all of Oregon. Oregon's private well page
- Certified labsOregon's list of certified labs
- Well recordsOregon's well record search
- New wellsUnder the Domestic Well Testing Act, sellers must test the well for arsenic, nitrate and total coliform bacteria during a real estate transaction and send the results to the buyer and OHA within 90 days.
Half the household wells here are shallower than 100 feet.
That comes from 16,363 household wells in Oregon's drilling records. Most wells of every kind here are 48 to 175 feet deep. Wells as deep as Linn County's are usually better protected from fertilizer and bacteria at the surface, but they can pick up more of what's in the rock, like arsenic and uranium. Typical household wells here are shallower than in 33 of the 35 other Oregon counties with enough drilling records.
Look up your own well's depth in Oregon's well record search, or see how to find it.
Well depths: US Groundwater Well Database
Here's what we know about radon and PFAS in Linn County.
Linn County is in the EPA's lowest radon zone, so radon from well water is unlikely to be a problem. Radon guide
Between 2023 and 2025 the EPA had 4 town water systems in Linn County test for PFAS. None found any. No well in Linn County has public PFAS results, so the town systems are the best clue to what's in the groundwater nearby. PFAS guide
Radon zones: EPA Map of Radon Zones. PFAS: EPA tests of town water systems, 2023 to 2025
Questions people ask about well water in Linn County
Is well water in Linn County safe to drink?
9 of 52 wells tested in Linn County had manganese over the limit, about 2 in 10. Across Oregon it's about 2 in 10. That's a smaller share than in 13 of the 25 other Oregon counties with 10 or more tested wells, leaving out 2 counties whose results are likely overstated. So test your own well for manganese before you count on it.
Where can I get my well tested in Linn County?
Use a lab Oregon has certified for drinking water. Oregon's list is linked above, in the box about testing. Ask for bacteria, nitrate, manganese and arsenic, the tests that matter most in Linn County.
How deep are wells in Linn County?
Half the household wells here are shallower than 100 feet. Typical household wells here are shallower than in 33 of the 35 other Oregon counties with enough drilling records.
How does Linn County compare with the counties around it?
For manganese, the share of tested wells over the limit: 2 of the 5 neighboring counties with data had a higher share than Linn County, at 17%. Marion had the most, at 47%. Groundwater doesn't stop at county lines, so Marion's 47% is worth knowing about if you live near it.
How often should I test my well in Linn County?
In Linn County, 4 of 23 tested wells had coliform bacteria, so the CDC's advice matters here: test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.
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Where the Linn County numbers come from
- People on wells: 51,436 in Linn County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 1,636 well water samples from 352 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2026.
- Well depths: 16,363 Oregon drilling records for Linn County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 6 counties that share a border with Linn County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 4 town water systems in Linn County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Linn County is zone 3 on the EPA Map of Radon Zones.
- State programs and links: Oregon Health Authority, checked November 1, 2026.