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Radon Levels in Otter Tail County, Minnesota

EPA puts Otter Tail County in Zone 1, its highest radon zone, and high results are common there: 61.4% of the 171 radon tests reported to CDC (2023) came back at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    61.4%

    26.8 pts above MN

    Otter Tail
    61.4%
    Minnesota
    34.6%

    171 tests, 2023

  • Median result

    4.8pCi/L

    Action level reached

    Otter Tail
    4.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    171

    17th of 62 by tests

    Otter Tail
    171
    Hennepin
    6,545

    Reported to CDC before any fix, 2023

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Minnesota

    11 of 62

    Top quarter

    Otter Tail
    61.4%
    Renville
    75.7%

    By share, of 62 with 30+ tests

Read a result for Otter Tail County

Starts at Otter Tail County's median, 4.8 pCi/L

4.8pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 4.8 pCi/L

At or above 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 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. Otter Tail County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Otter Tail County, At a glance

Otter Tail County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Otter Tail County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

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 Otter Tail County, 2023

Share of reported tests at or above 4 pCi/L, by year, Otter Tail County
Share of reported tests at or above 4 pCi/L, by year, Otter Tail County
YearShare of reported tests at or above 4 pCi/L
201460.1%
201549.4%
201658.1%
201761.7%
201867.0%
201948.2%
202050.5%
202145.6%
202252.9%
202361.4%

2023: 61.4%. Across these years the share ran from 45.6% to 67.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 171 tests reported to CDC for Otter Tail County over 2023, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.

Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Otter Tail County, Compared

Otter Tail County radon figures, compared

Calculated by Radon411

More than half: 61.4% of the 171 radon tests reported to CDC for Otter Tail County in 2023 read at least 4 pCi/L. That places it 11th of 62 Minnesota counties with 30 or more tests for the same period. That is 26.8 points above the 34.6% pooled from 86 Minnesota counties.

The median result, 4.8 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 25.7 pCi/L. The rest split 16.4% under 2 pCi/L and 22.2% from 2 to 4 (Minnesota: 36.6% and 28.9%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 61.4% share point the same way here.

1 of its 4 bordering counties with figures ran higher, led by Clay County at 65.0%; Todd County reported 23.8%. Statewide for the same period, Renville County reported the highest share (75.7%) and Lake County the lowest (3.8%).

The busiest year on file was 2015, with 330 tests reported; the quietest, 2019, had 114.

Over 10 years of annual figures the share held within 2 points, from 60.1% in 2014 to 61.4% in 2023; its peak was 67.0% in 2018. Nationally, every county with a figure for the same period pools to 33.4%; Otter Tail County sits 28.0 points above it.

Share of reported tests at or above 4 pCi/L by year, Otter Tail County against Minnesota2014 to 2023, years with 30 or more tests: Otter Tail County 60.1% to 61.4%, the state's pooled share 34.6% in 2023.
Otter Tail CountyMinnesota, pooled
Share of reported tests at or above 4 pCi/L by year, Otter Tail County against Minnesota: data table
YearTestsOtter Tail County, at or above 4 pCi/LMinnesota, pooled
201424860.1%42.9%
201533049.4%43.6%
201624658.1%37.0%
201712861.7%38.2%
201818567.0%38.3%
201911448.2%36.1%
202022250.5%31.8%
202125945.6%33.1%
202213652.9%31.6%
202317161.4%34.6%
Otter Tail County against Minnesota, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Otter Tail County
Otter Tail County17161.4%4.8 pCi/LThis county
Minnesota, pooled86 counties, pooled22,44934.6%Not pooled−26.8 points
United States, pooled642 counties, pooled128,74033.4%Not pooled−28.0 points
Renville Countyhighest in the state3775.7%6.3 pCi/L+14.3 points
Lake Countylowest in the state783.8%1.3 pCi/L−57.6 points
Grant County, MNborders it1172.7%7.6 pCi/L+11.3 points
Clay County, MNborders it10065.0%5.5 pCi/L+3.6 points
Becker County, MNborders it4652.2%4.1 pCi/L−9.2 points
Douglas County, MNborders it14548.3%3.7 pCi/L−13.1 points
Wilkin County, MNborders it2748.1%3.6 pCi/L−13.3 points
Wadena County, MNborders it1540.0%2.8 pCi/L−21.4 points
Todd County, MNborders it6323.8%2.0 pCi/L−37.6 points
Where Otter Tail County's reported results fell, 2023, beside Minnesota and the United States
ResultOtter Tail County testsOtter Tail County shareMinnesota shareU.S. shareAgainst Minnesota
Under 2 pCi/L2816.4%36.6%41.4%−20.2 points
2 to 4 pCi/L3822.2%28.9%25.2%−6.7 points
4 pCi/L and above10561.4%34.6%33.4%+26.8 points
Otter Tail County ranked among the 62 Minnesota counties with 30 or more tests, by share at or above 4 pCi/L, 2023
CountyRankTestsAt or above 4 pCi/LMedian
Clay County6 of 6210065.0%5.5 pCi/L
Lyon County6 of 628065.0%6.1 pCi/L
Brown County8 of 6211563.5%5.4 pCi/L
Dodge County9 of 6215563.2%4.7 pCi/L
Le Sueur County10 of 6213562.2%5.1 pCi/L
Otter Tail County11 of 6217161.4%4.8 pCi/L
Waseca County12 of 626360.3%5.0 pCi/L
Polk County13 of 629060.0%4.7 pCi/L
Sibley County13 of 625560.0%5.0 pCi/L
Nobles County15 of 624158.5%4.7 pCi/L
McLeod County16 of 6213155.7%4.7 pCi/L
Otter Tail County radon tests by year, against Minnesota's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMinnesota, pooledChange from the row before
202317161.4%4.8 pCi/L25.7 pCi/L34.6%+8.5 points
202213652.9%4.1 pCi/L37.5 pCi/L31.6%+7.3 points
202125945.6%3.6 pCi/L27.9 pCi/L33.1%−4.9 points
202022250.5%4.1 pCi/L22.1 pCi/L31.8%+2.3 points
201911448.2%3.9 pCi/L15.7 pCi/L36.1%−18.8 points
201818567.0%5.3 pCi/L22.0 pCi/L38.3%+5.3 points
201712861.7%5.7 pCi/L26.8 pCi/L38.2%+3.6 points
201624658.1%4.6 pCi/L28.5 pCi/L37.0%+8.7 points
201533049.4%3.8 pCi/L63.4 pCi/L43.6%−10.7 points
201424860.1%5.0 pCi/L29.2 pCi/L42.9%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Otter Tail County, State data

Minnesota's own radon test data

Measured

What Minnesota's own agencies publish about radon tests in Otter Tail 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 Otter Tail 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

59.9%

845 properties tested with one or more tests at or above 4 pCi/L

Median result

4.5 pCi/L

Average result

6.1 pCi/L

Tests behind these figures

141 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.

Otter Tail County, Geology

The ground under Otter Tail County

Predicted

USGS's geologic map puts all of Otter Tail County's mapped land in one class: high radon potential. The map puts 51.0% of Otter Tail County in the area it calls Central Lowland-Western Lake Section and 49.0% in Central Lowland-Till Prairie. USGS gives both a radon index of 14, in the high band (12 to 17).

USGS's geologic areas under Otter Tail County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Central Lowland-Western Lake SectionSandy calcareous till derived from carbonate rocks.High1451.0%
Central Lowland-Till PrairieSilty and clayey till derived from shale and sandstone.High1449.0%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Otter Tail County beside the ground around it

Otter Tail County has more high-potential ground than Minnesota as a whole: 100% of its land against 61.1%. Of the 7 counties that border it, none has as large a share of high-potential ground; Becker County comes nearest at 100%.

Share of land by USGS radon potential: Otter Tail County, the 7 counties bordering it and Minnesota
AreaEPA zoneLow potentialModerate potentialHigh potential
Otter Tail CountyZone 1NoneNone100%
Becker CountyZone 1NoneNone100%
Wadena CountyZone 1None0.9%99.1%
Wilkin CountyZone 1NoneNone100%
Grant CountyZone 1NoneNone100%
Clay CountyZone 1NoneNone100%
Douglas CountyZone 1NoneNone100%
Todd CountyZone 1None22.7%77.3%
Minnesota87 counties, pooled by land areaVariesNone38.9%61.1%

The map rates the ground, not the air in any home.

Local help

Otter Tail County, Local resources

Radon testing and mitigation in Otter Tail County

Listed radon businesses with an address in Otter Tail County:

Listed radon professionals by town: Fergus Falls, Perham, Pelican Rapids, Battle Lake

What Minnesota's program says
Phone
651-201-4601
Email
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

Otter Tail County, Questions

Questions about radon in Otter Tail County

Are radon levels high in Otter Tail County?

In 2023, 61.4% of the radon tests reported to CDC for Otter Tail County, Minnesota were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.8 pCi/L. Of 62 Minnesota counties with 30 or more tests for the same period, 10 reported a higher share; pooled, the state comes to 34.6%.

Which counties border Otter Tail County?

Otter Tail County borders 7 counties: Becker County, Wadena County, Wilkin County, Grant County, Clay County, Douglas County and Todd County.

Products

Otter Tail County, Products

Testing a home in Otter Tail County

In Otter Tail County, 61.4% of 171 tests reported to CDC in 2023 reached 4 pCi/L, against 34.6% pooled across Minnesota. In Zone 1 the year-round level in Otter Tail 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

Otter Tail County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Otter Tail County

Explore

Otter Tail County, Bordering counties

Counties bordering Otter Tail County

Calculated by Radon411

Otter Tail County, Cities and towns

Cities and towns in Otter Tail County

The Census Bureau estimates 61,041 residents in Otter Tail County for July 1, 2025, 943 more than in 2020 (+1.6%). That works out to 31 people per square mile of land. Its largest town, Fergus Falls, has 14,246 residents, 23.3% of the total. CDC's 171 reported tests for 2023 work out to 2.8 per 1,000 residents (2025 estimate), close to Minnesota's 3.9.

From Fergus Falls to Urbank, CDC publishes no figure by town: each reads Otter Tail County's.

The 12 largest cities and towns in Otter Tail County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Fergus Falls14,246+1.0%23.3%
Wadenaextends beyond Otter Tail County4,341−0.4%Counted whole
Perham3,746+6.3%6.1%
Pelican Rapids2,608+0.5%4.3%
New York Mills1,481+9.5%2.4%
Parkers Prairie1,031+1.1%1.7%
Battle Lake930+8.4%1.5%
Henning859+0.2%1.4%
Ottertail734+14.5%1.2%
Rothsayextends beyond Otter Tail County486−2.6%Counted whole
Vergas370+7.9%0.6%
Underwood362+1.4%0.6%
  • Deer Creek
  • Dalton
  • Bluffton
  • Dent
  • Elizabeth
  • Erhard
  • Richville
  • Clitherall
  • Vining
  • Urbank

22 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Otter Tail County is counted whole, so it has no share.

Otter Tail County, Homes

Homes in Otter Tail County

Otter Tail County is a place of houses on their own lots: 81% of its 36,669 homes are detached single-family houses, against 66% across Minnesota. Half of its homes were built before 1978, close to Minnesota's 1978: 28% date from before 1960 and 25% from 2000 or later. Owners live in 79% of the occupied homes (Minnesota: 72%), so for most households a test and a fix are their own to order.

Homes in Otter Tail County, Minnesota, 2019 to 2023
HomesOtter Tail CountyMinnesota
Housing units36,6692,519,538
Detached houses81%66%
In buildings of 5 or more8%19%
Mobile homes6%3%
Built before 196028%29%
Built since 200025%22%
Middle year built19781978
Owner-occupied79%72%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.