Nitrate is widespread in Logan County wells.
1 widespread, 2 rare out of 3 health checks.
From 23 wells tested in Logan County since 2000; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: arsenic (7), uranium (2), lead (2).
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
5 in 10 people 24,838 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
How deep wells go here
Deep wells: fewer surface germs, more minerals from the rock.
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 Logan County compares with Oklahoma and the counties around it.
Each result puts Logan County next to the 7 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in Logan County wells.
Nitrate5 of 21 wells over
Too few tested to show: Noble.
These 2 are rare in Logan County.
Manganese0 of 20 wells over
* Likely overstated, so we don't rank it.
Too few tested to show: Noble, Payne.
Too few Logan County wells were tested for these 3.
Arsenic7 wells tested
Uranium2 wells tested
Lead2 wells tested
Every well needs a bacteria test every year.
No bacteria tests from Logan County wells are in the public data. Test every year anyway.
Iron reached staining levels in 0 of 20 tested wells, and it isn't a health risk.
Iron stains0 of 20 wells had it
Too few tested to show: Noble, Payne.
Most of the 23 wells tested in Logan County were last tested before 2010.
An old result shows the water as it was then, so treat these 23 wells as a starting point and test your own.
Most Logan 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 3 things to check in Logan County.
- Bacteria
- Nitrate
- Arsenic
What Oklahoma offers well owners
- Free testingWe didn't find a free program for all of Oklahoma. Oklahoma's private well page
- Certified labsOklahoma's list of certified labs
- Well recordsOklahoma's well record search
Half the household wells here are shallower than 180 feet.
That comes from 4,393 household wells in Oklahoma's drilling records. Most wells of every kind here are 110 to 200 feet deep. Wells as deep as Logan 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 go deeper than in 62 of the 75 other Oklahoma counties with enough drilling records.
Look up your own well's depth in Oklahoma'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 Logan County.
Logan 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 2 town water systems in Logan County test for PFAS. 1 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 4.3 ng/L of PFOA. No well in Logan 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 Logan County
Is well water in Logan County safe to drink?
5 of 21 wells tested in Logan County had nitrate over the limit, about 1 in 4. Across Oklahoma it's about 1 in 8. That's a bigger share than in 33 of the 39 other Oklahoma counties with 10 or more tested wells. So test your own well for nitrate before you count on it.
Where can I get my well tested in Logan County?
Use a lab Oklahoma has certified for drinking water. Oklahoma's list is linked above, in the box about testing. Ask for bacteria, nitrate and arsenic, the tests that matter most in Logan County.
How deep are wells in Logan County?
Half the household wells here are shallower than 180 feet. Typical household wells here go deeper than in 62 of the 75 other Oklahoma counties with enough drilling records.
How does Logan County compare with the counties around it?
For nitrate, the share of tested wells over the limit: 2 of the 6 neighboring counties with data had a higher share than Logan County, at 24%. Garfield had the most, at 31%. Groundwater doesn't stop at county lines, so Garfield's 31% is worth knowing about if you live near it.
How often should I test my well in Logan County?
Logan County has no public bacteria results for wells, so follow the CDC's advice: 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 Logan County numbers come from
- People on wells: 24,838 in Logan County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 176 well water samples from 23 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2008.
- Well depths: 4,393 Oklahoma drilling records for Logan County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 7 counties that share a border with Logan County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 2 town water systems in Logan County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Logan County is zone 3 on the EPA Map of Radon Zones.
- State programs and links: Department of Environmental Quality, checked November 1, 2026.