Locations and reports
Radon Levels in Watonwan County, Minnesota
What this means for you
- Your area: EPA rates Watonwan County Zone 1, the highest of its three radon zones. That is a prediction for the whole county, and homes with elevated levels occur in all three zones.
- Local tests: Of 24 radon tests reported to CDC for Watonwan County (2023), 66.7% were at or above 4 pCi/L, EPA's action level.
- Your home: The only way to know your home’s level is to test it.
pCi/L (picocuries per liter) is the unit radon is measured in. EPA recommends fixing a home at 4 pCi/L or above, its action level.
In 2023, 66.7% of the radon tests reported to CDC for Watonwan County, Minnesota came back at or above the EPA action level of 4 pCi/L, and the median result was 6.2 pCi/L. EPA's Map of Radon Zones places the county in Zone 1, highest predicted potential. Radon levels vary from home to home, so only a test measures the level in yours.
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county as a whole.
This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.
USGS geologic potential: Low across 100% of the county's land area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Watonwan County, 2023
- Tests reported
- 24
- At or above 4 pCi/L
- 66.7%
- Median result
- 6.2 pCi/L
Of 24 pre-mitigation tests reported to CDC, not homes in this area. CDC publishes the share in each band, not a count per band, so the per-band counts in the table are calculated by Radon411 and rounded to add up to the published total.
| Result band | Tests Calculated by Radon411 | Share Measured |
|---|---|---|
| Under 2 pCi/L | 3 | 12.5% |
| 2 to 4 pCi/L | 5 | 20.8% |
| 4 pCi/L and above | 16 | 66.7% |
Distribution of tested buildings, not this house. People testing before a sale, or because they suspect a problem, are over-represented in any reported testing data.
Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Watonwan County, In figures
Watonwan County in figures
What the published data says about Watonwan County, in words. A zone and a share of tests describe an area, never the level in any one home.
Predicted
PredictedEPA places Watonwan County in Zone 1, highest predicted potential, as it does 67 other counties of Minnesota's 87.
Of the 5 bordering counties, EPA places Blue Earth County, Brown County, Cottonwood County, Jackson County and Martin County in Zone 1.
Reported tests
MeasuredCDC has annual figures for Watonwan County for 10 years, 2014 to 2023. In 2023, 66.7% of 24 reported tests were at or above 4 pCi/L.
Across those years the share ranged from 37.2% (2021) to 68.6% (2014). Few tests in a year can move it a long way.
Local record
Minnesota's radon program is the MDH Indoor Air Unit, run by MN Dept. of Health; its contacts are under Local resources.
The county's largest incorporated places are St. James, Madelia and Butterfield; the figures here cover them as part of the county.
Watonwan County, Reported testing
Reported testing over time
Measured| Year | Median reported result | Highest reported result | Share of tests at or above 4 pCi/L |
|---|---|---|---|
| 2014 | 6.5 pCi/L | 28.0 pCi/L | 68.6% |
| 2015 | 5.7 pCi/L | 27.5 pCi/L | 61.3% |
| 2016 | 4.6 pCi/L | 38.5 pCi/L | 56.9% |
| 2017 | 5.1 pCi/L | 31.4 pCi/L | 55.6% |
| 2018 | 2.9 pCi/L | 12.2 pCi/L | 47.4% |
| 2019 | 4.0 pCi/L | 20.9 pCi/L | 50.0% |
| 2020 | 3.6 pCi/L | 32.7 pCi/L | 39.1% |
| 2021 | 3.0 pCi/L | 16.8 pCi/L | 37.2% |
| 2022 | 4.5 pCi/L | 26.4 pCi/L | 62.5% |
| 2023 | 6.2 pCi/L | 20.6 pCi/L | 66.7% |
What these figures count
Every percentage here is a share of radon tests reported to CDC for Watonwan County in 2023. It is not a share of homes in Watonwan County, and it is not a random sample: it counts only the tests people chose to run and that were reported.
The shares and the median are calculated from pre-mitigation tests (24 for 2023). CDC also reports the number of buildings tested (14), a different count, so the two totals are not interchangeable.
Watonwan County, State data
Minnesota's own radon test data
MeasuredWhat Minnesota's own agencies publish about radon tests in Watonwan County, with their period. These are not CDC's figures and are never added to them.
What the Minnesota Department of Health reports for Watonwan County
Radon Testing (MN Public Health Data Access Portal): home radon tests reported voluntarily by private laboratories and licensed radon measurement professionals, counted by property. Period: 2016-2025.
Share with one or more tests at or above 4 pCi/L
58.4%
122 properties tested with one or more tests at or above 4 pCi/L
Median result
4.4 pCi/L
Average result
5.8 pCi/L
Tests behind these figures
21 properties tested a year on average
- MDH says these data do not include all of the radon tests conducted in Minnesota.
- Post-mitigation tests are excluded from the averages and the median; the percentages use each property's highest test.
- Each home is unique and can have very different results than a neighbor's home; the only way to know is to test.
- These figures describe tests reported to the Minnesota Department of Health in this area. They count a different set of tests than CDC's figures and are not a reading of any one home.
Measured: Minnesota Department of Health data, 2016-2025.
Watonwan County, Comparison
How Watonwan County compares
MeasuredWatonwan County's own published CDC figures beside those of the counties that border it, for the same period.
Share of reported tests at or above 4 pCi/L
Measured2023, highest first. Each county’s own published CDC figure.
- Watonwan CountyThis page24 tests66.7%
- Brown CountyMN115 tests63.5%
- Jackson CountyMN44 tests52.3%
- Cottonwood CountyMN12 tests50.0%
- Martin CountyMN81 tests43.2%
- Blue Earth CountyMN392 tests32.7%
Median reported result
Measured2023, highest first. Each county’s own published CDC figure.
- Watonwan CountyThis page24 tests6.2 pCi/L
- Brown CountyMN115 tests5.4 pCi/L
- Jackson CountyMN44 tests4.1 pCi/L
- Cottonwood CountyMN12 tests3.5 pCi/L
- Martin CountyMN81 tests3.5 pCi/L
- Blue Earth CountyMN392 tests2.2 pCi/L
Each figure is that county’s own published CDC figure for 2023, counting radon tests reported to CDC, not homes. Watonwan County is this page. Nothing is averaged or combined across counties. The test count beside each county is CDC’s published number of pre-mitigation tests behind its figures. Figures from few tests can swing widely from year to year. Every Minnesota county’s own figure is in the Minnesota county table.
CDC publishes this figure only for counties here, so there is no state or national number to compare Watonwan County, Minnesota with.
Watonwan County, Bordering counties
Counties bordering Watonwan County
Calculated by Radon4115 counties share a boundary with Watonwan County, computed from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county’s report can be worth reading alongside this one.
Watonwan County, Local resources
Local resources in Minnesota
Who to ask in Minnesota: the state's radon program, test kits and professionals.
MDH Indoor Air Unit
MN Dept. of Health
Minnesota’s radon program answers questions about testing, mitigation and the rules where you live.
- Phone
- 651-201-4601
- health.indoorair@state.mn.us
- Licensing of radon professionals
The Radon Licensing Act requires anyone who performs a radon test or radon mitigation, in a building they do not own or lease, must be licensed by MDH.
- Disclosure when a home is sold or rented
The Minnesota Radon Awareness Act requires specific disclosure and education be provided to potential home buyers during residential real estate transactions in Minnesota.
Test kits
Ask the program whether it has free or discounted kits, or compare kits you can buy.
Radon professionals
7 professionals are listed in Minnesota.
Professionals in MinnesotaWatonwan County, Cities and towns
Cities and towns in Watonwan County
The radon figures on this page are for Watonwan County as a whole. They do not differ by city or town.
- St. James
- Madelia
- Butterfield
- Lewisville
- Odin
- Ormsby (part)
- Darfur
- La Salle
8 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county.
Watonwan County, Questions
Questions about radon in Watonwan County
Common questions8 questions, answered from the figures above
Are radon levels high in Watonwan County?
In 2023, 66.7% of the radon tests reported to CDC for Watonwan County, Minnesota were at or above 4 pCi/L, and the median reported pre-mitigation result was 6.2 pCi/L. That is a share of reported tests, not of homes. EPA places Watonwan County in Zone 1, highest predicted potential, a predicted average indoor screening level greater than 4 pCi/L. Homes with elevated levels occur in all three zones, so the figures describe the area, not your house. Testing is the only way to know the radon level in a specific building.
How do I get a radon test in Watonwan County?
EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. No certified tester listed on Radon411 names Watonwan County as a service area yet. The Minnesota radon program is the place to ask about certified testers and any test kit offer it runs.
How to test a homeTest kits comparedFree and low-cost kits by stateMinnesota radon program
Who does radon mitigation in Watonwan County?
No listed mitigator names Watonwan County as a service area yet; the Minnesota directory lists 7 companies. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional. Your state radon program is the place to check whether Minnesota requires one.
How radon mitigation worksWhat mitigation costsMitigators in Minnesota
What EPA radon zone is Watonwan County in?
EPA places Watonwan County, Minnesota in Zone 1, which EPA describes as highest predicted potential for the area. A zone is a prediction for the whole county and never determines whether a particular home should be tested. EPA recommends testing every home regardless of zone.
Should I test my home in Watonwan County?
Yes. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. How to test a home.
When is the best time of year to test?
EPA says short-term tests stay in the home from 2 to 90 days and that all radon tests should run a minimum of 48 hours; long-term tests stay more than 90 days. EPA's guides do not name a best season: they say radon levels tend to vary from day to day and season to season, so a long-term test is more likely than a short-term test to tell you the year-round average.
What does it cost to test?
EPA's Citizen's Guide calls testing easy and inexpensive, and EPA's Home Buyer's and Seller's Guide says passive short-term and long-term devices are generally inexpensive, while active devices may cost more. No national average price is published for this, so Radon411 does not give one. What testing costs.
Which counties border Watonwan County?
Watonwan County borders 5 counties, derived from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county's report can be relevant.
What these figures mean if you own, buy, sell or rent
The reported-test figures on this page describe Watonwan County, Minnesota in 2023. They describe tests other people carried out in other buildings, and none of them measures yours.
- How to test a home
If you own your home
Test the lowest lived-in level; a short-term kit screens in days, a long-term kit reflects the year.
- Buying a house: radon guide
If you are buying
Ask for past results and any system's post-mitigation test, and test during the sale.
- Selling a house: radon guide
If you are selling
Testing before you list puts the timing in your hands; disclosure rules differ by state.
- Radon in rental homes
If you rent, or rent out a home
A tenant can test; a fix is the owner's to make, and duties differ by state.
How long a test has to run, under what conditions, and what EPA says a result means: the testing standard, in full.
Watonwan County, Products
Testing and mitigation products
Whatever the figures for Watonwan County show, only a test tells you about one home.
Testing
- Short-term test kitsPassive detectors exposed for a few days under closed-building conditions, then analyzed by a lab.
- Long-term test kitsDetectors exposed for more than 90 days, for a closer picture of the annual average.
- Continuous monitorsPowered devices that log radon on a repeating cycle, often used for transaction tests.
- Digital detectorsConsumer devices that display a running radon reading without a lab.
- Water radon testsKits for radon dissolved in well water, analyzed by a lab.
Mitigation
- Mitigation fansThe inline fan that keeps a soil depressurization system running, sized by the installer.
- System indicatorsU-tube manometers and fan alarms that show whether a mitigation system is still working.
- Sealing materialsCrack, joint and sump sealing used alongside a mitigation system, not instead of one.
Watonwan County / Next steps
What to do next
Learn
Know what radon is
What radon is, how it gets indoors, and why a county zone is not a reading for your home.
Learn about radonTest
Test the building you live in
Short-term or long-term, where the device goes, and closed-house conditions.
How to testFix
Bring a high level down
How a mitigation system works, and the retest that confirms it.
How mitigation worksFind a pro
Hire a certified professional
Measurement and mitigation professionals by state, with their certifications.
Find a professional
Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.