Nitrate is widespread in Dakota County wells.
1 widespread, 1 worth checking, 4 rare out of 6 health checks.
From 158 wells tested in Dakota County since 2000; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: radon (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
1 in 11 people 39,861 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 Dakota County compares with Minnesota and the counties around it.
Each result puts Dakota County next to the 7 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in Dakota County wells.
Nitrate32 of 154 wells over
Too few tested to show: Ramsey, Rice.
This one is worth checking in Dakota County.
Manganese13 of 128 wells over
Too few tested to show: Pierce, WI, Scott.
These 4 are rare in Dakota County.
Arsenic0 of 123 wells over
Too few tested to show: Goodhue, Pierce, WI, Scott.
Uranium0 of 10 wells over
Too few tested to show: Goodhue, Pierce, WI, Ramsey, Rice, Scott, Washington.
Lead0 of 123 wells over
Too few tested to show: Goodhue, Pierce, WI, Scott.
Fluoride0 of 138 wells over
Too few tested to show: Pierce, WI, Ramsey, Scott.
Too few Dakota County wells were tested for this one.
Radon in water2 wells tested
Coliform bacteria turned up in 13 of 23 tested Dakota County wells, so test for it every year.
Coliform bacteria13 of 23 wells had it
Too few tested to show: Goodhue, Hennepin, Pierce, WI, Ramsey, Rice.
E. coli9 of 22 wells had it
Too few tested to show: Goodhue, Hennepin, Pierce, WI, Ramsey, Rice.
E. coli means human or animal waste is getting in, so if a test of your Dakota County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 72 of 128 tested wells, and it isn't a health risk.
Iron stains72 of 128 wells had it
Too few tested to show: Pierce, WI, Scott.
About 8 in 10 of the 158 wells tested in Dakota County have a test from 2020 or later.
With 123 wells tested since 2020, age matters less here than who did the testing and why.
Most Dakota 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 Dakota County.
- Bacteria
- Nitrate
- Manganese
- Arsenic
What Minnesota offers well owners
- Free testingWe didn't find a free program for all of Minnesota. Minnesota's private well page
- Certified labsMinnesota's list of certified labs
- Well recordsMinnesota's well record search
- New wellsThe well contractor must collect an initial water sample after construction to test for coliform bacteria, nitrate, and arsenic before the well is used.
Half the household wells here are shallower than 260 feet.
That comes from 6,663 household wells in Minnesota's drilling records. Most wells of every kind here are 160 to 320 feet deep. Wells as deep as Dakota 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 83 of the 86 other Minnesota counties with enough drilling records.
Look up your own well's depth in Minnesota'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 Dakota County.
Dakota 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 9 town water systems in Dakota County test for PFAS. 2 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 24 ng/L of PFOA. Only 13 wells in Dakota County have 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 Dakota County
Is well water in Dakota County safe to drink?
32 of 154 wells tested in Dakota County had nitrate over the limit, about 2 in 10. Across Minnesota it's about 1 in 14. That's a bigger share than in 49 of the 53 other Minnesota 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 Dakota County?
Use a lab Minnesota has certified for drinking water. Minnesota's list is linked above, in the box about testing. Ask for bacteria, nitrate, manganese and arsenic, the tests that matter most in Dakota County.
How deep are wells in Dakota County?
Half the household wells here are shallower than 260 feet. Typical household wells here go deeper than in 83 of the 86 other Minnesota counties with enough drilling records.
How does Dakota County compare with the counties around it?
For nitrate, the share of tested wells over the limit: 1 of the 5 neighboring counties with data had a higher share than Dakota County, at 21%. Pierce, WI had the most, at 23%. Groundwater doesn't stop at county lines, so Pierce, WI's 23% is worth knowing about if you live near it.
How often should I test my well in Dakota County?
In Dakota County, 13 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 Dakota County numbers come from
- People on wells: 39,861 in Dakota County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 1,807 well water samples from 158 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2025.
- Well depths: 6,663 Minnesota drilling records for Dakota County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 7 counties that share a border with Dakota County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 9 town water systems in Dakota County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Dakota County is zone 1 on the EPA Map of Radon Zones.
- State programs and links: Minnesota Department of Health, checked November 1, 2026.