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 Portage County, Wisconsin
EPA puts Portage County in Zone 1, its highest radon zone, and 35.6% of its 334 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
35.6%
0.1 pts below WI
- Portage
- 35.6%
- Wisconsin
- 35.7%
334 tests, 2023
Median result
3.0pCi/L
Below action level
- Portage
- 3.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
334
19th of 69 by tests
- Portage
- 334
- Dane
- 2,887
Reported to CDC before any fix, 2023
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Wisconsin
41 of 69
Middle half
- Portage
- 35.6%
- Langlade
- 65.8%
By share, of 69 with 30+ tests
Read a result for Portage County
Starts at Portage County's median, 3.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.0 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. Portage County's median reported result, 2023.
The data
Portage County, At a glance
Portage County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Portage County in
USGS geologic potential: High across 76% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Portage County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 51.2% |
| 2015 | 55.8% |
| 2016 | 45.2% |
| 2017 | 32.7% |
| 2019 | 54.3% |
| 2020 | 43.3% |
| 2021 | 55.3% |
| 2022 | 44.6% |
| 2023 | 35.6% |
2023: 35.6%. Across these years the share ran from 32.7% to 55.8%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 334 tests reported to CDC for Portage 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).
Portage County, Compared
Portage County radon figures, compared
Calculated by Radon411In Portage County, about 4 in 10 reported tests in 2023 (119 of 334) were at or above EPA's action level. Against the national pool of 33.4%, the gap is 2.2 points higher. Across 72 Wisconsin counties pooled together, 35.7% of tests reached that level, so Portage County runs 0.1 points below its state.
Of 6 neighbours with a figure, 3 reported a larger share at or above 4 pCi/L and 3 a smaller one; the spread is 18.3% (Wood County) to 57.0% (Shawano County). By share, Portage County is 41st of 69 Wisconsin counties with 30 or more tests for the same period.
Year by year, 2014 opened at 51.2% and 2023 closed at 35.6% (down 15.6 points), with 2015 the high at 55.8%. Half the tests came in under 3.0 pCi/L and half over it; the single highest reached 61.1 pCi/L. Below the action level, 119 tests (35.6%) came in under 2 pCi/L, against 41.4% statewide, and 96 tests (28.7%) fell between 2 and 4, against 23.0% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 35.6% share point the same way here. USGS geology rates 76% of the county's land high radon potential. CDC also counts 7 tests taken after mitigation in Portage County for the same period: tests in homes where a fix was already in.
The busiest year on file was 2023, with 334 tests reported; the quietest, 2020, had 150.
Portage CountyWisconsin, pooled
| Year | Tests | Portage County, at or above 4 pCi/L | Wisconsin, pooled |
|---|---|---|---|
| 2014 | 201 | 51.2% | 51.1% |
| 2015 | 163 | 55.8% | 51.6% |
| 2016 | 230 | 45.2% | 45.2% |
| 2017 | 226 | 32.7% | 44.8% |
| 2019 | 199 | 54.3% | 42.9% |
| 2020 | 150 | 43.3% | 27.0% |
| 2021 | 235 | 55.3% | 39.9% |
| 2022 | 204 | 44.6% | 42.9% |
| 2023 | 334 | 35.6% | 35.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Portage County, Geology
The ground under Portage County
PredictedMost of the ground under Portage County is one class on USGS's geologic map: 76.0% of its land is high radon potential, with 24.0% moderate. The map puts 76.0% of Portage County in the area it calls Wolf River Batholith and 12.2% in Green Bay Lobe, with one smaller area beside them. USGS gives the first a radon index of 13, in the high band (12 to 17), and the second 10, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Wolf River Batholith | Plutonic granitic rocks including quartz monzonite, syenite, monzonite, anorthosite. | High | 13 | 76.0% |
| Green Bay Lobe | Glacial deposits derived from carbonate and igneous rocks. | Moderate | 10 | 12.2% |
| Central Plain/Northern Highland | Pre-Late Wisconsinan glacial deposits derived from sandstone and carbonate rocks. | Moderate | 10 | 11.8% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Portage County beside the ground around it
Portage County has more high-potential ground than Wisconsin as a whole: 76.0% of its land against 34.8%. Of the 6 counties that border it, 1 has more high-potential ground, Marathon County the most at 84.0%.
The map rates the ground, not the air in any home.
Local help
Portage County, Local resources
Radon testing and mitigation in Portage 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
Portage County, Questions
Questions about radon in Portage County
Are radon levels high in Portage County?
In 2023, 35.6% of the radon tests reported to CDC for Portage County, Wisconsin were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.0 pCi/L. Of 69 Wisconsin counties with 30 or more tests for the same period, 40 reported a higher share; pooled, the state comes to 35.7%.
Which counties border Portage County?
Portage County borders 6 counties: Waushara County, Waupaca County, Wood County, Adams County, Marathon County and Shawano County.
Products
Portage County, Products
Testing a home in Portage County
In Portage County, 35.6% of 334 tests reported to CDC in 2023 reached 4 pCi/L, against 35.7% pooled across Wisconsin. In Zone 1 the year-round level in Portage 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
MonitorForensics Detectors
FD-65-RADON rechargeable radon detector with a color screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
Short-term kitempowerDX
Standard Radon Test short-term mail-in radon test kit
- Lab fee included
Method: Passive sampler
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Portage County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Portage County
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Portage County, Bordering counties
Counties bordering Portage County
Calculated by Radon411- Radon levels in Shawano CountyEPA zone 1
57.0%at or above 4 pCi/L
Median 5.0 pCi/L · 114 tests · 21.4 points above Portage County
- Radon levels in Waupaca CountyEPA zone 1
52.8%at or above 4 pCi/L
Median 4.3 pCi/L · 127 tests · 17.2 points above Portage County
- Radon levels in Marathon CountyEPA zone 1
51.9%at or above 4 pCi/L
Median 4.3 pCi/L · 349 tests · 16.3 points above Portage County
- Radon levels in Waushara CountyEPA zone 2
25.4%at or above 4 pCi/L
Median 1.9 pCi/L · 71 tests · 10.2 points below Portage County
- Radon levels in Adams CountyEPA zone 2
20.8%at or above 4 pCi/L
Median 1.7 pCi/L · 48 tests · 14.8 points below Portage County
- Radon levels in Wood CountyEPA zone 1
18.3%at or above 4 pCi/L
Median 1.4 pCi/L · 208 tests · 17.3 points below Portage County
Portage County, Cities and towns
Cities and towns in Portage County
The Census Bureau estimates 71,943 residents in Portage County for July 1, 2025, 1,520 more than in 2020 (+2.2%). That works out to 90 people per square mile of land. Its largest town, Stevens Point, has 26,377 residents, 36.7% of the total. CDC's 334 reported tests for 2023 work out to 4.6 per 1,000 residents (2025 estimate), close to Wisconsin's 3.5.
From Stevens Point to Nelsonville, CDC publishes no figure by town: each reads Portage County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Stevens Point | 26,377 | +2.7% | 36.7% |
| Plover | 14,274 | +5.3% | 19.8% |
| Whiting | 1,649 | +2.9% | 2.3% |
| Amherst | 1,119 | +0.6% | 1.6% |
| Park Ridge | 545 | +3.4% | 0.8% |
| Rosholt | 465 | −2.5% | 0.6% |
| Junction City | 449 | +7.7% | 0.6% |
| Almond | 414 | −2.6% | 0.6% |
| Amherst Junction | 376 | −2.1% | 0.5% |
| Milladoreextends beyond Portage County | 263 | −1.5% | Counted whole |
| Nelsonville | 169 | +0.6% | 0.2% |
11 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 Portage County is counted whole, so it has no share.
Portage County, Homes
Homes in Portage County
Of Portage County's 31,496 homes, 69% are detached houses, against 66% across Wisconsin; 14% are in buildings of five or more homes. Half of its homes were built before 1979, close to Wisconsin's 1975: 25% date from before 1960 and 20% from 2000 or later. 69% 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 | Portage County | Wisconsin |
|---|---|---|
| Housing units | 31,496 | 2,750,750 |
| Detached houses | 69% | 66% |
| In buildings of 5 or more | 14% | 17% |
| Mobile homes | 4% | 3% |
| Built before 1960 | 25% | 34% |
| Built since 2000 | 20% | 20% |
| Middle year built | 1979 | 1975 |
| Owner-occupied | 69% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.