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 Clay County, Minnesota
EPA puts Clay County in Zone 1, its highest radon zone, and high results are common there: 65.0% of the 100 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
Share at 4+ pCi/L
65.0%
30.4 pts above MN
- Clay
- 65.0%
- Minnesota
- 34.6%
100 tests, 2023
Median result
5.5pCi/L
Action level reached
- Clay
- 5.5 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
100
34th of 62 by tests
- Clay
- 100
- Hennepin
- 6,545
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 Minnesota
6 of 62
Top quarter
- Clay
- 65.0%
- Renville
- 75.7%
By share, of 62 with 30+ tests
Read a result for Clay County
Starts at Clay County's median, 5.5 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 5.5 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. Clay County's median reported result, 2023.
The data
Clay County, At a glance
Clay County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Clay 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 Clay County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 65.3% |
| 2015 | 62.7% |
| 2016 | 64.0% |
| 2017 | 62.4% |
| 2018 | 64.6% |
| 2019 | 60.0% |
| 2020 | 44.1% |
| 2021 | 54.9% |
| 2022 | 41.8% |
| 2023 | 65.0% |
2023: 65.0%. Across these years the share ran from 41.8% to 65.3%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 100 tests reported to CDC for Clay 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).
Clay County, Compared
Clay County radon figures, compared
Calculated by Radon411More than half: 65.0% of the 100 radon tests reported to CDC for Clay County in 2023 read at least 4 pCi/L. That places it 6th of 62 Minnesota counties with 30 or more tests for the same period. That is 30.4 points above the 34.6% pooled from 86 Minnesota counties.
The median result, 5.5 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 31.3 pCi/L. The rest split 20.0% under 2 pCi/L and 15.0% from 2 to 4 (Minnesota: 36.6% and 28.9%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 65.0% share point the same way here.
No bordering county with a figure for the same period reported a higher share; the closest is Otter Tail County at 61.4%, the lowest Becker County at 52.2%. 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 2018, with 554 tests reported; the quietest, 2023, had 100.
Over 10 years of annual figures the share held within 2 points, from 65.3% in 2014 to 65.0% in 2023; its peak was 65.3% in 2014. Nationally, every county with a figure for the same period pools to 33.4%; Clay County sits 31.6 points above it.
Clay CountyMinnesota, pooled
65.0% % of tests34.6% % of tests
| Year | Tests | Clay County, at or above 4 pCi/L | Minnesota, pooled |
|---|---|---|---|
| 2014 | 202 | 65.3% | 42.9% |
| 2015 | 225 | 62.7% | 43.6% |
| 2016 | 161 | 64.0% | 37.0% |
| 2017 | 165 | 62.4% | 38.2% |
| 2018 | 554 | 64.6% | 38.3% |
| 2019 | 125 | 60.0% | 36.1% |
| 2020 | 111 | 44.1% | 31.8% |
| 2021 | 164 | 54.9% | 33.1% |
| 2022 | 201 | 41.8% | 31.6% |
| 2023 | 100 | 65.0% | 34.6% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Clay County, State data
Minnesota's own radon test data
MeasuredWhat Minnesota's own agencies publish about radon tests in Clay 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 Clay 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
59.4%
1,241 properties tested with one or more tests at or above 4 pCi/L
Median result
4.7 pCi/L
Average result
6.4 pCi/L
Tests behind these figures
209 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.
Clay County, Geology
The ground under Clay County
PredictedUSGS's geologic map puts all of Clay County's mapped land in one class: high radon potential. The map puts 71.9% of Clay County in the area it calls Lake Agassiz Plain and 27.9% in Central Lowland-Till Prairie. USGS gives the first a radon index of 15 and the second 14, both in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Lake Agassiz Plain | Silt and clay deposits of Glacial Lake Agassiz derived from Cretaceous shales containing higher than average amounts of uranium. | High | 15 | 71.9% |
| Central Lowland-Till Prairie | Silty and clayey till derived from shale and sandstone. | High | 14 | 27.9% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Clay County beside the ground around it
Clay County has more high-potential ground than Minnesota as a whole: 100% of its land against 61.1%. Of the 6 counties that border it, none has as large a share of high-potential ground; Becker County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Clay County, Local resources
Radon testing and mitigation in Clay County
Listed radon businesses with an address in Clay 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.
Listed radon professionals by town: Moorhead
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
Clay County, Questions
Questions about radon in Clay County
Are radon levels high in Clay County?
In 2023, 65.0% of the radon tests reported to CDC for Clay County, Minnesota were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.5 pCi/L. Of 62 Minnesota counties with 30 or more tests for the same period, 5 reported a higher share; pooled, the state comes to 34.6%.
Which counties border Clay County?
Clay County borders 6 counties: Norman County, MN, Cass County, ND, Becker County, MN, Wilkin County, MN, Otter Tail County, MN and Richland County, ND.
Products
Clay County, Products
Testing a home in Clay County
In Clay County, 65.0% of 100 tests reported to CDC in 2023 reached 4 pCi/L, against 34.6% pooled across Minnesota. In Zone 1 the year-round level in Clay 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
Monitor
RM-63Pro rechargeable radon monitor with a touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
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
Clay County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Clay County
Explore
Clay County, Bordering counties
Counties bordering Clay County
Calculated by Radon411- Radon levels in Otter Tail County, MNEPA zone 1
61.4%at or above 4 pCi/L
Median 4.8 pCi/L · 171 tests · 3.6 points below Clay County
- Radon levels in Becker County, MNEPA zone 1
52.2%at or above 4 pCi/L
Median 4.1 pCi/L · 46 tests · 12.8 points below Clay County
- Radon levels in Wilkin County, MNEPA zone 1
48.1%at or above 4 pCi/L
Median 3.6 pCi/L · 27 tests · 16.9 points below Clay County
- Radon levels in Norman County, MNEPA zone 1
37.5%at or above 4 pCi/L
Median 3.0 pCi/L · 8 tests · 27.5 points below Clay County
- Radon levels in Cass County, NDEPA zone 1
No CDC figure for 2023; its page reads it against its own neighbours.
- Radon levels in Richland County, NDEPA zone 1
No CDC figure for 2023; its page reads it against its own neighbours.
Clay County, Cities and towns
Cities and towns in Clay County
The Census Bureau estimates 67,734 residents in Clay County for July 1, 2025, 2,376 more than in 2020 (+3.6%). That works out to 65 people per square mile of land. Moorhead alone is home to 46,533 of them, 68.7% of the total. Together its 11 incorporated places hold 87.7% of those residents; the other 12.3% live outside any of them. Reported testing is thin here: 100 tests over 2023, or 1.5 for every 1,000 residents (2025 estimate), where Minnesota as a whole comes to 3.9.
From Moorhead to Georgetown, CDC publishes no figure by town: each reads Clay County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Moorhead | 46,533 | +4.5% | 68.7% |
| Dilworth | 4,823 | +4.6% | 7.1% |
| Barnesville | 2,767 | +0.2% | 4.1% |
| Hawley | 2,285 | +2.1% | 3.4% |
| Glyndon | 1,393 | +6.3% | 2.1% |
| Sabin | 601 | −2.6% | 0.9% |
| Ulen | 473 | −1.0% | 0.7% |
| Hitterdal | 204 | +1.0% | 0.3% |
| Felton | 169 | −2.9% | 0.2% |
| Comstock | 102 | +2.0% | 0.2% |
| Georgetown | 86 | −3.4% | 0.1% |
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).
Clay County, Homes
Homes in Clay County
Of Clay County's 27,241 homes, 60% are detached houses, against 66% across Minnesota; 25% are in buildings of five or more homes. Half of its homes were built before 1981, close to Minnesota's 1978: 24% date from before 1960 and 31% from 2000 or later. 67% of occupied homes are lived in by their owner (Minnesota: 72%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Clay County | Minnesota |
|---|---|---|
| Housing units | 27,241 | 2,519,538 |
| Detached houses | 60% | 66% |
| In buildings of 5 or more | 25% | 19% |
| Mobile homes | 2% | 3% |
| Built before 1960 | 24% | 29% |
| Built since 2000 | 31% | 22% |
| Middle year built | 1981 | 1978 |
| Owner-occupied | 67% | 72% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.