Short-term kit
PicoCan short-term charcoal canister radon test
- Lab fee included
Method: Charcoal
In home: 48 to 96 hours
Locations and reports
Radon Levels in Columbia County, Wisconsin
EPA puts Columbia County in Zone 2, its middle radon zone, and 28.8% of its 163 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
Share at 4+ pCi/L
28.8%
6.9 pts below WI
- Columbia
- 28.8%
- Wisconsin
- 35.7%
163 tests, 2023
Median result
2.0pCi/L
Below action level
- Columbia
- 2.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
163
33rd of 69 by tests
- Columbia
- 163
- Dane
- 2,887
Reported to CDC before any fix, 2023
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Rank in Wisconsin
52 of 69
Middle half
- Columbia
- 28.8%
- Langlade
- 65.8%
By share, of 69 with 30+ tests
Read a result for Columbia County
Starts at Columbia County's median, 2.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.0 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 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. Columbia County's median reported result, 2023.
The data
Columbia County, At a glance
Columbia County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Columbia County is a
USGS geologic potential: Moderate across 64% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Columbia County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 37.8% |
| 2015 | 60.9% |
| 2016 | 39.7% |
| 2017 | 40.5% |
| 2019 | 50.7% |
| 2020 | 43.2% |
| 2021 | 31.1% |
| 2022 | 44.6% |
| 2023 | 28.8% |
2023: 28.8%. Across these years the share ran from 28.8% to 60.9%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 163 tests reported to CDC for Columbia 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).
Columbia County, Compared
Columbia County radon figures, compared
Calculated by Radon411Columbia County's 163 reported tests in 2023 had a middle value of 2.0 pCi/L and a maximum of 56.4 pCi/L, and 28.8% reached 4 pCi/L. Wisconsin as a whole (72 Wisconsin counties, pooled) comes to 35.7%: 6.9 points higher than here.
Among its state's counties it ranks 52nd of 69 Wisconsin counties with 30 or more tests for the same period. Statewide for the same period, Langlade County reported the highest share (65.8%) and Bayfield County the lowest (5.7%).
Below the action level, 78 tests (47.9%) came in under 2 pCi/L, against 41.4% statewide, and 38 tests (23.3%) fell between 2 and 4, against 23.0% statewide. The busiest year on file was 2023, with 163 tests reported; the quietest, 2021, had 61.
EPA's 1993 zone map puts Columbia County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 64% of the county's land moderate radon potential.
Next door, the shares run from 10.0% in Juneau County to 54.9% in Dodge County, with Adams County, Marquette County and Juneau County below Columbia County. Over 9 years of annual figures the share fell 9.0 points, from 37.8% in 2014 to 28.8% in 2023; its peak was 60.9% in 2015.
Columbia CountyWisconsin, pooled
| Year | Tests | Columbia County, at or above 4 pCi/L | Wisconsin, pooled |
|---|---|---|---|
| 2014 | 127 | 37.8% | 51.1% |
| 2015 | 87 | 60.9% | 51.6% |
| 2016 | 68 | 39.7% | 45.2% |
| 2017 | 79 | 40.5% | 44.8% |
| 2019 | 73 | 50.7% | 42.9% |
| 2020 | 95 | 43.2% | 27.0% |
| 2021 | 61 | 31.1% | 39.9% |
| 2022 | 74 | 44.6% | 42.9% |
| 2023 | 163 | 28.8% | 35.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Columbia County, Geology
The ground under Columbia County
PredictedUSGS's geologic map splits Columbia County: 64.1% of its land is moderate radon potential and 35.9% high. The map puts 61.4% of Columbia County in the area it calls Green Bay Lobe and 35.9% in Eastern Ridges and Lowlands, with one smaller area beside them. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 12, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Green Bay Lobe | Glacial deposits derived from carbonate and igneous rocks. | Moderate | 10 | 61.4% |
| Eastern Ridges and Lowlands | Glacial deposits derived from Ordovician carbonate rocks. | High | 12 | 35.9% |
| Driftless Area | Cambrian sandstone. | Moderate | 10 | 2.7% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Columbia County beside the ground around it
On high-potential ground Columbia County is close to Wisconsin as a whole: 35.9% of its land against 34.8%. Of the 7 counties that border it, 3 have more high-potential ground, Dodge County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Columbia County, Local resources
Radon testing and mitigation in Columbia County
- Wisconsin's radon programWisconsin Department of Health ServicesWisconsin's radon program does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Wisconsin.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
We recommend starting with your regional Radon Information Center since many centers provide test kits for free or reduced cost, and often with laboratory fees covered.
- Compare kits
- Professionals in Wisconsin19 professionals are listed in Wisconsin.
What Wisconsin's program says
- Phone
- 1-888-569-7236
- 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
Columbia County, Questions
Questions about radon in Columbia County
Are radon levels high in Columbia County?
In 2023, 28.8% of the radon tests reported to CDC for Columbia County, Wisconsin were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.0 pCi/L. Of 69 Wisconsin counties with 30 or more tests for the same period, 51 reported a higher share; pooled, the state comes to 35.7%.
Which counties border Columbia County?
Columbia County borders 7 counties: Green Lake County, Marquette County, Sauk County, Dodge County, Dane County, Adams County and Juneau County.
Products
Columbia County, Products
Testing a home in Columbia County
In Columbia County, 28.8% of 163 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 Columbia County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
Monitor
RM-65 rechargeable radon detector with a color screen and alarm
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Columbia County, Bordering counties
Counties bordering Columbia County
Calculated by Radon411- Radon levels in Dodge CountyEPA zone 1
54.9%at or above 4 pCi/L
Median 4.8 pCi/L · 257 tests · 26.1 points above Columbia County
- Radon levels in Sauk CountyEPA zone 2
41.1%at or above 4 pCi/L
Median 3.3 pCi/L · 241 tests · 12.3 points above Columbia County
- Radon levels in Green Lake CountyEPA zone 1
40.5%at or above 4 pCi/L
Median 3.4 pCi/L · 79 tests · 11.7 points above Columbia County
- Radon levels in Dane CountyEPA zone 1
34.9%at or above 4 pCi/L
Median 2.5 pCi/L · 2,887 tests · 6.1 points above Columbia County
- Radon levels in Adams CountyEPA zone 2
20.8%at or above 4 pCi/L
Median 1.7 pCi/L · 48 tests · 8.0 points below Columbia County
- Radon levels in Marquette CountyEPA zone 2
15.0%at or above 4 pCi/L
Median 1.3 pCi/L · 40 tests · 13.8 points below Columbia County
- Radon levels in Juneau CountyEPA zone 2
10.0%at or above 4 pCi/L
Median 1.1 pCi/L · 50 tests · 18.8 points below Columbia County
Columbia County, Cities and towns
Cities and towns in Columbia County
About 58,132 people live in Columbia County by the Census Bureau's estimate for July 1, 2025, 402 fewer than in 2020 (−0.7%). That works out to 76 people per square mile of land. No town dominates: Portage, the largest, has 9,956 residents, 17.1% of the total. CDC's 163 reported tests for 2023 work out to 2.8 per 1,000 residents (2025 estimate), close to Wisconsin's 3.5.
From Portage to Doylestown, CDC publishes no figure by town: each reads Columbia County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Portage | 9,956 | −5.9% | 17.1% |
| Columbusextends beyond Columbia County | 5,400 | −2.4% | Counted whole |
| Lodi | 3,190 | −0.1% | 5.5% |
| Wisconsin Dellsextends beyond Columbia County | 3,149 | +4.5% | Counted whole |
| Poynette | 2,924 | +12.5% | 5.0% |
| Pardeeville | 2,248 | +8.4% | 3.9% |
| Fall River | 1,853 | −0.1% | 3.2% |
| Randolphextends beyond Columbia County | 1,771 | −1.3% | Counted whole |
| Rio | 1,123 | −0.4% | 1.9% |
| Arlington | 860 | +1.3% | 1.5% |
| Cambria | 765 | −0.9% | 1.3% |
| Wyocena | 733 | −3.6% | 1.3% |
- Friesland
- Doylestown
14 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 Columbia County is counted whole, so it has no share.
Columbia County, Homes
Homes in Columbia County
Columbia County is a place of houses on their own lots: 77% of its 26,826 homes are detached single-family houses, against 66% across Wisconsin. Half of its homes were built before 1976, close to Wisconsin's 1975: 35% date from before 1960 and 21% from 2000 or later. Owners live in 77% of the occupied homes (Wisconsin: 68%), so for most households a test and a fix are their own to order.
| Homes | Columbia County | Wisconsin |
|---|---|---|
| Housing units | 26,826 | 2,750,750 |
| Detached houses | 77% | 66% |
| In buildings of 5 or more | 9% | 17% |
| Mobile homes | 3% | 3% |
| Built before 1960 | 35% | 34% |
| Built since 2000 | 21% | 20% |
| Middle year built | 1976 | 1975 |
| Owner-occupied | 77% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.