Manganese is widespread in St. Louis County wells.
1 widespread, 4 rare out of 5 health checks.
From 195 wells tested in St. Louis County since 2009; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: uranium (1), radon (1).
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 62,498 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)
Possible here. A home air test is inexpensive.
Radon zones: EPA map
Here's how St. Louis County compares with Minnesota and the counties around it.
Each result puts St. Louis County next to the 6 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in St. Louis County wells.
Manganese48 of 189 wells over
Too few tested to show: Douglas, WI, Koochiching.
These 4 are rare in St. Louis County.
Arsenic5 of 195 wells over
Too few tested to show: Douglas, WI, Itasca, Koochiching.
Nitrate0 of 194 wells over
Too few tested to show: Douglas, WI, Koochiching.
Lead0 of 195 wells over
Too few tested to show: Douglas, WI, Itasca, Koochiching.
Fluoride0 of 195 wells over
Too few tested to show: Douglas, WI, Itasca, Koochiching.
Too few St. Louis County wells were tested for these 2.
Uranium1 well tested
Radon in water1 well tested
None of the 1 St. Louis County wells tested for bacteria had it, but every well needs a yearly test.
Coliform bacteria0 of 1 wells had it
E. coli0 of 1 wells had it
E. coli means human or animal waste is getting in, so if a test of your St. Louis County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 80 of 195 tested wells, and it isn't a health risk.
Iron stains80 of 195 wells had it
Too few tested to show: Douglas, WI, Koochiching.
About 10 in 10 of the 195 wells tested in St. Louis County have a test from 2020 or later.
With 188 wells tested since 2020, age matters less here than who did the testing and why.
Most St. Louis 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 St. Louis 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 108 feet.
That comes from 18,666 household wells in Minnesota's drilling records. Most wells of every kind here are 71 to 259 feet deep. Wells as deep as St. Louis 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 57 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 St. Louis County.
St. Louis County is in the EPA's middle radon zone. An indoor air test is cheap and tells you whether to look at your water. Radon guide
Between 2023 and 2025 the EPA had 9 town water systems in St. Louis County test for PFAS. 1 found some PFAS, all below the new limits. Only 9 wells in St. Louis 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 St. Louis County
Is well water in St. Louis County safe to drink?
48 of 189 wells tested in St. Louis County had manganese over the limit, about 1 in 4. Across Minnesota it's about 2 in 10. That's a bigger share than in 25 of the 44 other Minnesota counties with 10 or more tested wells, leaving out 1 county 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 St. Louis 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 St. Louis County.
How deep are wells in St. Louis County?
Half the household wells here are shallower than 108 feet. Typical household wells here are shallower than in 57 of the 86 other Minnesota counties with enough drilling records.
How does St. Louis County compare with the counties around it?
For manganese, the share of tested wells over the limit: 2 of the 4 neighboring counties with data had a higher share than St. Louis County, at 25%. Carlton had the most, at 32%. Groundwater doesn't stop at county lines, so Carlton's 32% is worth knowing about if you live near it.
How often should I test my well in St. Louis County?
None of the 1 wells tested for bacteria in St. Louis County had it, but the CDC still says to 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 St. Louis County numbers come from
- People on wells: 62,498 in St. Louis County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 1,702 well water samples from 195 wells in the Water Quality Portal, run by the USGS and EPA, 2009 to 2025.
- Well depths: 18,666 Minnesota drilling records for St. Louis County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 6 counties that share a border with St. Louis County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 9 town water systems in St. Louis County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: St. Louis County is zone 2 on the EPA Map of Radon Zones.
- State programs and links: Minnesota Department of Health, checked November 1, 2026.