Nitrate is widespread in Woodbury County wells.
1 widespread, 2 worth checking, 2 rare out of 5 health checks.
From 39 wells tested in Woodbury 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 8 people 12,509 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)
Likely here. Test your home's air first.
Radon zones: EPA map
Here's how Woodbury County compares with Iowa and the counties around it.
Each result puts Woodbury County next to the 8 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in Woodbury County wells.
Nitrate4 of 18 wells over
Too few tested to show: Crawford, Ida, Union, SD.
These 2 are worth checking in Woodbury County.
Manganese4 of 37 wells over
Too few tested to show: Thurston, NE, Union, SD.
Arsenic3 of 37 wells over
Too few tested to show: Thurston, NE, Union, SD.
These 2 are rare in Woodbury County.
Fluoride0 of 37 wells over
Too few tested to show: Thurston, NE, Union, SD.
Lead0 of 37 wells over
Too few tested to show: Dakota, NE, Thurston, NE, Union, SD.
Coliform bacteria turned up in 1 of 2 tested Woodbury County wells, so test for it every year.
Coliform bacteria1 of 2 wells had it
E. coli0 of 2 wells had it
E. coli means human or animal waste is getting in, so if a test of your Woodbury County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 19 of 37 tested wells, and it isn't a health risk.
Iron stains19 of 37 wells had it
Too few tested to show: Thurston, NE, Union, SD.
Most of the 39 wells tested in Woodbury County were last tested before 2010.
An old result shows the water as it was then, so treat these 39 wells as a starting point and test your own.
Most Woodbury 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 Woodbury County.
- Bacteria
- Nitrate
- Manganese
- Arsenic
What Iowa offers well owners
- Free testingIowa's Private Well Grants program provides free testing for bacteria, nitrate, arsenic, and manganese through participating county environmental health offices. See the program
- Certified labsIowa's list of certified labs
- Well recordsIowa's well record search
Half the household wells here are shallower than 198 feet.
That comes from 680 household wells in Iowa's drilling records. Most wells of every kind here are 67 to 208 feet deep. Wells as deep as Woodbury 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 60 of the 92 other Iowa counties with enough drilling records.
Look up your own well's depth in Iowa'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 Woodbury County.
Woodbury County is in the EPA's highest radon zone. Radon from well water adds to the radon in your indoor air, so test your air first, and your water too if the air is high. Radon guide
Between 2023 and 2025 the EPA had 2 town water systems in Woodbury 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 6.0 ng/L of PFOA. No well in Woodbury 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 Woodbury County
Is well water in Woodbury County safe to drink?
4 of 18 wells tested in Woodbury County had nitrate over the limit, about 2 in 10. Across Iowa it's about 1 in 12. That's a bigger share than in 32 of the 36 other Iowa counties with 10 or more tested wells, leaving out 1 county whose results are likely overstated. So test your own well for nitrate before you count on it.
Can I get my well tested for free in Woodbury County?
Iowa's Private Well Grants program provides free testing for bacteria, nitrate, arsenic, and manganese through participating county environmental health offices. If not, use a lab Iowa has certified for drinking water. Ask for bacteria, nitrate, manganese and arsenic, the tests that matter most in Woodbury County.
How deep are wells in Woodbury County?
Half the household wells here are shallower than 198 feet. Typical household wells here go deeper than in 60 of the 92 other Iowa counties with enough drilling records.
How does Woodbury County compare with the counties around it?
For nitrate, the share of tested wells over the limit: 2 of the 5 neighboring counties with data had a higher share than Woodbury County, at 22%. Plymouth had the most, at 31%. Groundwater doesn't stop at county lines, so Plymouth's 31% is worth knowing about if you live near it.
How often should I test my well in Woodbury County?
In Woodbury County, 1 of 2 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 Woodbury County numbers come from
- People on wells: 12,509 in Woodbury County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 248 well water samples from 39 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2016.
- Well depths: 680 Iowa drilling records for Woodbury County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 8 counties that share a border with Woodbury County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 2 town water systems in Woodbury County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Woodbury County is zone 1 on the EPA Map of Radon Zones.
- State programs and links: Iowa Department of Natural Resources, checked November 1, 2026.