Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Watonwan County, Minnesota
EPA puts Watonwan County in Zone 1, its highest radon zone, and only 24 radon tests from it are on file with CDC (2023). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
62.7%
19.3 pts above MN
- Watonwan
- 62.7%
- Minnesota
- 43.4%
292 tests, 2008 to 2017
Median result
5.3pCi/L
Action level reached
- Watonwan
- 5.3 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
292
58th of 85 by tests
- Watonwan
- 292
- Hennepin
- 35,213
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Minnesota
31 of 85
Middle half
- Watonwan
- 62.7%
- Rock
- 83.8%
By share, of 85 with 30+ tests
Read a result for Watonwan County
Starts at Watonwan County's median, 5.3 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 5.3 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Watonwan County's median reported result, 2008 to 2017.
The data
Watonwan County, At a glance
Watonwan County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Watonwan County in
USGS geologic potential: High across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Watonwan County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 68.6% |
| 2015 | 61.3% |
| 2016 | 56.9% |
| 2017 | 55.6% |
| 2018 | 47.4% |
| 2019 | 50.0% |
| 2020 | 39.1% |
| 2021 | 37.2% |
| 2022 | 62.5% |
| 2023 | 66.7% |
2023: 66.7%. Across these years the share ran from 37.2% to 68.6%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
Only 24 tests were reported to CDC for Watonwan County over 2023, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.
Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Watonwan County, Compared
Watonwan County radon figures, compared
Calculated by Radon411More than half: 62.7% of the 292 radon tests reported to CDC for Watonwan County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 31st of 85 Minnesota counties with 30 or more tests for the same period. That is 19.3 points above the 43.4% pooled from 87 Minnesota counties.
The newest figure, in 2023, counts only 24 tests (66.7% at or above 4 pCi/L), too few to compare, so this reading uses the 292-test figure.
The median result, 5.3 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 47.9 pCi/L. The rest split 15.8% under 2 pCi/L and 21.6% from 2 to 4 (Minnesota: 27.4% and 29.2%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 62.7% share point the same way here.
All 5 of its bordering counties with figures ran higher, led by Brown County at 73.7%; the lowest of them, Blue Earth County, reported 64.8%. Statewide for the same period, Rock County reported the highest share (83.8%) and Anoka County the lowest (17.4%).
The busiest year on file was 2015, with 93 tests reported; the quietest, 2019, had 12.
Over 6 years of annual figures the share fell 6.1 points, from 68.6% in 2014 to 62.5% in 2022; its peak was 68.6% in 2014. Nationally, every county with a figure for the same period pools to 35.7%; Watonwan County sits 27.0 points above it. CDC also counts 63 tests taken after mitigation in Watonwan County for the same period: tests in homes where a fix was already in.
Watonwan CountyMinnesota, pooled
62.5% % of tests31.6% % of tests
| Year | Tests | Watonwan County, at or above 4 pCi/L | Minnesota, pooled |
|---|---|---|---|
| 2014 | 51 | 68.6% | 42.9% |
| 2015 | 93 | 61.3% | 43.6% |
| 2016 | 58 | 56.9% | 37.0% |
| 2020 | 64 | 39.1% | 31.8% |
| 2021 | 43 | 37.2% | 33.1% |
| 2022 | 48 | 62.5% | 31.6% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
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.
MeasuredState figures, not CDC's
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, Geology
The ground under Watonwan County
PredictedUSGS's geologic map puts all of Watonwan County's mapped land in one class: high radon potential. The map puts 70.3% of Watonwan County in the area it calls Central Lowland-Till Prairie and 29.7% in Glacial Lake Deposits. USGS gives both a radon index of 14, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Central Lowland-Till Prairie | Silty and clayey till derived from shale and sandstone. | High | 14 | 70.3% |
| Glacial Lake Deposits | Silt and clay glacial lake deposits. | High | 14 | 29.7% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Watonwan County beside the ground around it
Watonwan County has more high-potential ground than Minnesota as a whole: 100% of its land against 61.1%. Of the 5 counties that border it, none has as large a share of high-potential ground; Blue Earth County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Watonwan County, Local resources
Radon testing and mitigation in Watonwan County
- MDH Indoor Air UnitMDH Indoor Air Unit, run by MN Dept. of Health, licenses or certifies radon professionals and states the rule for disclosing radon when a home is sold, and answers questions about testing and mitigation in Minnesota.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsAsk the program whether it has free or discounted kits, or compare kits you can buy.
- Compare kits
- Professionals in Minnesota255 professionals are listed in Minnesota.
What Minnesota's program says
- 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.
What it means
Watonwan County, Questions
Questions about radon in Watonwan County
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. Of 85 Minnesota counties with 30 or more tests for the same period, 30 reported a higher share; pooled, the state comes to 43.4%.
Which counties border Watonwan County?
Watonwan County borders 5 counties: Martin County, Brown County, Blue Earth County, Cottonwood County and Jackson County.
Products
Watonwan County, Products
Testing a home in Watonwan County
In Watonwan County, 62.7% of 292 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 43.4% pooled across Minnesota. In Zone 1 the year-round level in Watonwan County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.
Test kits and monitors3
See every kit and monitor
MonitorAranet
Radon One battery digital radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- Alarm
- Screen, app
Method: Ion chamber
First reading: Within 10 minutes
Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Watonwan County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Watonwan County
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Watonwan County, Bordering counties
Counties bordering Watonwan County
Calculated by Radon411- Radon levels in Brown CountyEPA zone 1
73.7%at or above 4 pCi/L
Median 6.7 pCi/L · 1,476 tests · 11.0 points above Watonwan County
- Radon levels in Jackson CountyEPA zone 1
69.8%at or above 4 pCi/L
Median 6.8 pCi/L · 394 tests · 7.1 points above Watonwan County
- Radon levels in Cottonwood CountyEPA zone 1
68.1%at or above 4 pCi/L
Median 6.3 pCi/L · 427 tests · 5.4 points above Watonwan County
- Radon levels in Martin CountyEPA zone 1
64.9%at or above 4 pCi/L
Median 5.2 pCi/L · 405 tests · 2.2 points above Watonwan County
- Radon levels in Blue Earth CountyEPA zone 1
64.8%at or above 4 pCi/L
Median 5.6 pCi/L · 1,884 tests · 2.1 points above Watonwan County
Watonwan County, Cities and towns
Cities and towns in Watonwan County
The Census Bureau estimates 11,459 residents in Watonwan County for July 1, 2025, 223 more than in 2020 (+2.0%). That works out to 26 people per square mile of land. Its largest town, St. James, has 4,863 residents, 42.4% of the total. CDC's 292 reported tests for 2008 to 2017 work out to 25.5 per 1,000 residents (2025 estimate), close to Minnesota's 22.5.
From St. James to La Salle, CDC publishes no figure by town: each reads Watonwan County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| St. James | 4,863 | +1.2% | 42.4% |
| Madelia | 2,488 | +3.7% | 21.7% |
| Butterfield | 611 | +1.8% | 5.3% |
| Lewisville | 208 | +1.5% | 1.8% |
| Odin | 127 | +1.6% | 1.1% |
| Ormsbyextends beyond Watonwan County | 122 | +2.5% | Counted whole |
| Darfur | 84 | Level | 0.7% |
| La Salle | 75 | +1.4% | 0.7% |
8 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Watonwan County is counted whole, so it has no share.
Watonwan County, Homes
Homes in Watonwan County
Watonwan County is a place of houses on their own lots: 79% of its 4,904 homes are detached single-family houses, against 66% across Minnesota. The homes are older than Minnesota's as a whole: half were built before 1961 (1978 for Minnesota), and 48% date from before 1960. Owners live in 78% of the occupied homes (Minnesota: 72%), so for most households a test and a fix are their own to order.
| Homes | Watonwan County | Minnesota |
|---|---|---|
| Housing units | 4,904 | 2,519,538 |
| Detached houses | 79% | 66% |
| In buildings of 5 or more | 10% | 19% |
| Mobile homes | 5% | 3% |
| Built before 1960 | 48% | 29% |
| Built since 2000 | 10% | 22% |
| Middle year built | 1961 | 1978 |
| Owner-occupied | 78% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.