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Radon Levels in Eau Claire County, Wisconsin

EPA puts Eau Claire County in Zone 2, its middle radon zone, and 32.7% of its 474 reported radon tests (2023) were 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

    32.7%

    3.0 pts below WI

    Eau Claire
    32.7%
    Wisconsin
    35.7%

    474 tests, 2023

  • Median result

    2.8pCi/L

    Below action level

    Eau Claire
    2.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    474

    8th of 69 by tests

    Eau Claire
    474
    Dane
    2,887

    Reported to CDC before any fix, 2023

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in Wisconsin

    47 of 69

    Middle half

    Eau Claire
    32.7%
    Langlade
    65.8%

    By share, of 69 with 30+ tests

Read a result for Eau Claire County

Starts at Eau Claire County's median, 2.8 pCi/L

2.8pCi/L

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

EPA’s reading of 2.8 pCi/L

Between 2 and 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Eau Claire County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Eau Claire County, At a glance

Eau Claire County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Eau Claire County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Moderate across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Eau Claire County, 2023

Share of reported tests at or above 4 pCi/L, by year, Eau Claire County
Share of reported tests at or above 4 pCi/L, by year, Eau Claire County
YearShare of reported tests at or above 4 pCi/L
201441.9%
201546.9%
201637.0%
201738.2%
201926.7%
202033.2%
202131.5%
202242.0%
202332.7%

2023: 32.7%. Across these years the share ran from 26.7% to 46.9%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 474 tests reported to CDC for Eau Claire 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

Eau Claire County, Compared

Eau Claire County radon figures, compared

Calculated by Radon411

In Eau Claire County, about 3 in 10 reported tests in 2023 (155 of 474) were at or above EPA's action level. Against the national pool of 33.4%, the gap is 0.7 points lower. Across 72 Wisconsin counties pooled together, 35.7% of tests reached that level, so Eau Claire County runs 3.0 points below its state.

Of 7 neighbours with a figure, 5 reported a larger share at or above 4 pCi/L and 2 a smaller one; the spread is 15.4% (Pepin County) to 53.6% (Buffalo County). By share, Eau Claire County is 47th of 69 Wisconsin counties with 30 or more tests for the same period.

Year by year, 2014 opened at 41.9% and 2023 closed at 32.7% (down 9.2 points), with 2015 the high at 46.9%. Half the tests came in under 2.8 pCi/L and half over it; the single highest reached 156.6 pCi/L. Below the action level, 166 tests (35.0%) came in under 2 pCi/L, against 41.4% statewide, and 153 tests (32.3%) fell between 2 and 4, against 23.0% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 32.7% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential. CDC also counts 24 tests taken after mitigation in Eau Claire County for the same period: tests in homes where a fix was already in.

The busiest year on file was 2023, with 474 tests reported; the quietest, 2021, had 216.

Share of reported tests at or above 4 pCi/L by year, Eau Claire County against Wisconsin2014 to 2023, years with 30 or more tests: Eau Claire County 41.9% to 32.7%, the state's pooled share 35.7% in 2023.
Eau Claire CountyWisconsin, pooled
Share of reported tests at or above 4 pCi/L by year, Eau Claire County against Wisconsin: data table
YearTestsEau Claire County, at or above 4 pCi/LWisconsin, pooled
201427041.9%51.1%
201537346.9%51.6%
201634137.0%45.2%
201735138.2%44.8%
201926226.7%42.9%
202026233.2%27.0%
202121631.5%39.9%
202233342.0%42.9%
202347432.7%35.7%
Eau Claire County against Wisconsin, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Eau Claire County
Eau Claire County47432.7%2.8 pCi/LThis county
Wisconsin, pooled72 counties, pooled20,87935.7%Not pooled+3.0 points
United States, pooled642 counties, pooled128,74033.4%Not pooled+0.7 points
Langlade Countyhighest in the state22565.8%6.0 pCi/L+33.1 points
Bayfield Countylowest in the state355.7%1.5 pCi/L−27.0 points
Buffalo County, WIborders it5653.6%4.4 pCi/L+20.9 points
Trempealeau County, WIborders it11242.0%3.3 pCi/L+9.3 points
Jackson County, WIborders it9338.7%3.2 pCi/L+6.0 points
Dunn County, WIborders it17137.4%2.9 pCi/L+4.7 points
Chippewa County, WIborders it31135.7%2.5 pCi/L+3.0 points
Clark County, WIborders it7525.3%2.2 pCi/L−7.4 points
Pepin County, WIborders it6515.4%1.2 pCi/L−17.3 points
Where Eau Claire County's reported results fell, 2023, beside Wisconsin and the United States
ResultEau Claire County testsEau Claire County shareWisconsin shareU.S. shareAgainst Wisconsin
Under 2 pCi/L16635.0%41.4%41.4%−6.4 points
2 to 4 pCi/L15332.3%23.0%25.2%+9.3 points
4 pCi/L and above15532.7%35.7%33.4%−3.0 points
Eau Claire County ranked among the 69 Wisconsin counties with 30 or more tests, by share at or above 4 pCi/L, 2023
CountyRankTestsAt or above 4 pCi/LMedian
Dane County42 of 692,88734.9%2.5 pCi/L
Barron County43 of 6919934.7%2.5 pCi/L
Green County44 of 6923533.6%2.1 pCi/L
Polk County45 of 6912233.6%2.8 pCi/L
Richland County46 of 694833.3%2.9 pCi/L
Eau Claire County47 of 6947432.7%2.8 pCi/L
La Crosse County48 of 6977131.4%2.7 pCi/L
Manitowoc County49 of 6920931.1%2.2 pCi/L
Pierce County50 of 6913630.9%2.7 pCi/L
Ashland County51 of 694129.3%2.3 pCi/L
Columbia County52 of 6916328.8%2.0 pCi/L
Eau Claire County radon tests by year, against Wisconsin's pooled share
YearTestsAt or above 4 pCi/LMedianHighestWisconsin, pooledChange from the row before
202347432.7%2.8 pCi/L156.6 pCi/L35.7%−9.3 points
202233342.0%3.4 pCi/L41.4 pCi/L42.9%+10.5 points
202121631.5%2.9 pCi/L68.2 pCi/L39.9%−1.7 points
202026233.2%2.6 pCi/L39.0 pCi/L27.0%+6.5 points
201926226.7%2.6 pCi/L43.8 pCi/L42.9%−11.5 points
201735138.2%3.1 pCi/L193.5 pCi/L44.8%+1.2 points
201634137.0%3.2 pCi/L74.7 pCi/L45.2%−9.9 points
201537346.9%3.6 pCi/L52.7 pCi/L51.6%+5.0 points
201427041.9%3.7 pCi/L62.8 pCi/L51.1%First on file

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

Eau Claire County, Geology

The ground under Eau Claire County

Predicted

USGS's geologic map puts all of Eau Claire County's mapped land in one class: moderate radon potential. The map puts 94.6% of Eau Claire County in the area it calls Central Plain/Northern Highland and 5.4% in Driftless Area. USGS gives both a radon index of 10, in the moderate band (9 to 11).

USGS's geologic areas under Eau Claire County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Central Plain/Northern HighlandPre-Late Wisconsinan glacial deposits derived from sandstone and carbonate rocks.Moderate1094.6%
Driftless AreaCambrian sandstone.Moderate105.4%

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

Eau Claire County beside the ground around it

Across Wisconsin 34.8% of the land is rated high; none of Eau Claire County's is. Of the 7 counties that border it, 5 have more high-potential ground, Buffalo County the most at 84.2%.

Share of land by USGS radon potential: Eau Claire County, the 7 counties bordering it and Wisconsin
AreaEPA zoneLow potentialModerate potentialHigh potential
Eau Claire CountyZone 2None100%None
Chippewa CountyZone 2None100%None
Trempealeau CountyZone 2None65.7%34.3%
Clark CountyZone 2None97.5%2.5%
Dunn CountyZone 2None90.3%9.7%
Buffalo CountyZone 1None15.8%84.2%
Jackson CountyZone 2None100%None
Pepin CountyZone 1None44.8%55.2%
Wisconsin72 counties, pooled by land areaVaries1.4%63.5%34.8%

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

Local help

Eau Claire County, Local resources

Radon testing and mitigation in Eau Claire County

What Wisconsin's program says
Phone
1-888-569-7236
Email
DHSRadon@dhs.wisconsin.gov
Licensing of radon professionals
The State of Wisconsin does not require contractors performing radon measurement or mitigation work to be state licensed or nationally certified.

What it means

Eau Claire County, Questions

Questions about radon in Eau Claire County

Are radon levels high in Eau Claire County?

In 2023, 32.7% of the radon tests reported to CDC for Eau Claire County, Wisconsin were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.8 pCi/L. Of 69 Wisconsin counties with 30 or more tests for the same period, 46 reported a higher share; pooled, the state comes to 35.7%.

Which counties border Eau Claire County?

Eau Claire County borders 7 counties: Chippewa County, Trempealeau County, Clark County, Dunn County, Buffalo County, Jackson County and Pepin County.

Products

Eau Claire County, Products

Testing a home in Eau Claire County

In Eau Claire County, 32.7% of 474 tests reported to CDC in 2023 reached 4 pCi/L, against 35.7% pooled across Wisconsin. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Eau Claire County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Eau Claire County homes, compared

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Eau Claire County, Bordering counties

Counties bordering Eau Claire County

Calculated by Radon411

Eau Claire County, Cities and towns

Cities and towns in Eau Claire County

The Census Bureau estimates 109,033 residents in Eau Claire County for July 1, 2025, 3,135 more than in 2020 (+3.0%). That works out to 171 people per square mile of land. Eau Claire, the largest place on its list (72,465 residents in all), extends beyond Eau Claire County, so no share of the total is worked out for it. CDC's 474 reported tests for 2023 work out to 4.3 per 1,000 residents (2025 estimate), close to Wisconsin's 3.5.

From Eau Claire to Fairchild, CDC publishes no figure by town: each reads Eau Claire County's.

The cities and towns in Eau Claire County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Eau Claireextends beyond Eau Claire County72,465+4.3%Counted whole
Altoona9,376+11.4%8.6%
Augusta1,483−5.7%1.4%
Fall Creek1,390−2.5%1.3%
Fairchild435−3.1%0.4%

5 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 Eau Claire County is counted whole, so it has no share.

Eau Claire County, Homes

Homes in Eau Claire County

Of Eau Claire County's 45,818 homes, 62% are detached houses, against 66% across Wisconsin; 16% are in buildings of five or more homes. Half of its homes were built before 1977, close to Wisconsin's 1975: 31% date from before 1960 and 20% from 2000 or later. 63% of occupied homes are lived in by their owner (Wisconsin: 68%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Eau Claire County, Wisconsin, 2019 to 2023
HomesEau Claire CountyWisconsin
Housing units45,8182,750,750
Detached houses62%66%
In buildings of 5 or more16%17%
Mobile homes3%3%
Built before 196031%34%
Built since 200020%20%
Middle year built19771975
Owner-occupied63%68%

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