Skip to content
RADON411

Locations and reports

Radon Levels in Walsh County, North Dakota

EPA puts Walsh County in Zone 1, its highest radon zone, and high results are common there: 79.5% of the 132 radon tests reported to CDC (2008 to 2017, laboratory totals) 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

    79.5%

    20.2 pts above ND

    Walsh
    79.5%
    ND
    59.3%

    132 tests, 2008 to 2017

  • Median result

    9.8pCi/L

    Action level reached

    Walsh
    9.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    132

    11th of 29 by tests

    Walsh
    132
    Burleigh
    1,558

    Reported to CDC before any fix, 2008 to 2017

  • 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 ND

    2 of 29

    Top quarter

    Walsh
    79.5%
    Pembina
    82.5%

    By share, of 29 with 30+ tests

Read a result for Walsh County

Starts at Walsh County's median, 9.8 pCi/L

9.8pCi/L

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

EPA’s reading of 9.8 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. Walsh County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Walsh County, At a glance

Walsh County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Walsh 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 Walsh County, 2008 to 2017, laboratory

Reported results by concentration band, Walsh County, 2008 to 2017, laboratory
Under 2 pCi/L: 11%2 to 4 pCi/L: 10%4 pCi/L and above: 79%

Of 132 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Walsh County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L1410.6%
2 to 4 pCi/L139.8%
4 pCi/L and above10579.5%
What these figures count

These are the 132 tests reported to CDC for Walsh County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Walsh County, Compared

Walsh County radon figures, compared

Calculated by Radon411

More than half: 79.5% of the 132 radon tests reported to CDC for Walsh County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 2nd of 29 North Dakota counties with 30 or more tests for the same period. That is 20.2 points above the 59.3% pooled from 53 North Dakota counties.

The median result, 9.8 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 102.9 pCi/L. The rest split 10.6% under 2 pCi/L and 9.8% from 2 to 4 (North Dakota: 18.3% and 22.4%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 79.5% share point the same way here.

1 of its 4 bordering counties with figures ran higher, led by Pembina County at 82.5%; Marshall County, MN reported 55.6%. Statewide for the same period, Pembina County reported the highest share (82.5%) and Williams County the lowest (33.8%).

CDC's ten-year totals for Walsh County went from 145 tests (2005 to 2014) to 132 (2008 to 2017), the share going from 76.6% to 79.5%.

Nationally, every county with a figure for the same period pools to 35.7%; Walsh County sits 43.8 points above it. CDC also counts 10 tests taken after mitigation in Walsh County for the same period: tests in homes where a fix was already in.

Walsh County against North Dakota, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Walsh County
Walsh County13279.5%9.8 pCi/LThis county
North Dakota, pooled53 counties, pooled6,60759.3%Not pooled−20.2 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−43.8 points
Benson Countyhighest in the state3177.4%6.2 pCi/L−2.1 points
Williams Countylowest in the state20433.8%2.9 pCi/L−45.7 points
Pembina County, NDborders it5782.5%9.3 pCi/L+3.0 points
Ramsey County, NDborders it13476.9%6.9 pCi/L−2.6 points
Grand Forks County, NDborders it68075.9%8.8 pCi/L−3.6 points
Nelson County, NDborders it1963.2%5.7 pCi/L−16.3 points
Marshall County, MNborders it9955.6%5.4 pCi/L−23.9 points
Cavalier County, NDborders it2850.0%3.9 pCi/L−29.5 points
Where Walsh County's reported results fell, 2008 to 2017, laboratory, beside North Dakota and the United States
ResultWalsh County testsWalsh County shareNorth Dakota shareU.S. shareAgainst North Dakota
Under 2 pCi/L1410.6%18.3%39.6%−7.7 points
2 to 4 pCi/L139.8%22.4%24.7%−12.6 points
4 pCi/L and above10579.5%59.3%35.7%+20.2 points
Walsh County ranked among the 29 North Dakota counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Pembina County1 of 295782.5%9.3 pCi/L
Walsh County2 of 2913279.5%9.8 pCi/L
Benson County3 of 293177.4%6.2 pCi/L
Ramsey County4 of 2913476.9%6.9 pCi/L
Grand Forks County5 of 2968075.9%8.8 pCi/L
Dunn County6 of 293574.3%7.1 pCi/L
Stutsman County7 of 2935173.5%5.8 pCi/L
McIntosh County8 of 293271.9%7.0 pCi/L
Bowman County9 of 293571.4%5.8 pCi/L
LaMoure County10 of 294470.5%5.2 pCi/L
Barnes County11 of 298367.5%5.6 pCi/L
Walsh County ten-year laboratory totals, against North Dakota's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestNorth Dakota, pooledChange from the row before
2008 to 201713279.5%9.8 pCi/L102.9 pCi/L59.3%+1.7 points
2007 to 201615377.8%9.5 pCi/L102.9 pCi/L58.7%−0.5 points
2006 to 201515778.3%9.7 pCi/L81.0 pCi/L56.3%+1.7 points
2005 to 201414576.6%8.7 pCi/L81.0 pCi/L54.0%First on file

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

Walsh County, Geology

The ground under Walsh County

Predicted

USGS's geologic map puts all of Walsh County's mapped land in one class: high radon potential. The map puts 58.9% of Walsh County in the area it calls Glacial Lakes and 41.0% in Great Plains (Glaciated). USGS gives the first a radon index of 14 and the second 13, both in the high band (12 to 17).

USGS's geologic areas under Walsh County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Glacial LakesSilt and clay deposits of Glacial Lake Agassiz derived from Cretaceous shales containing higher than average amounts of uranium.High1458.9%
Great Plains (Glaciated)Glacial deposits derived from Cretaceous shales containing higher than average amounts of uranium.High1341.0%

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

Walsh County beside the ground around it

On high-potential ground Walsh County is close to North Dakota as a whole: 100% of its land against 98.9%. Of the 6 counties that border it, none has as large a share of high-potential ground; Grand Forks County comes nearest at 100%.

Share of land by USGS radon potential: Walsh County, the 6 counties bordering it and North Dakota
AreaEPA zoneLow potentialModerate potentialHigh potential
Walsh CountyZone 1NoneNone100%
Pembina CountyZone 1NoneNone99.8%
Grand Forks CountyZone 1NoneNone100%
Nelson CountyZone 1NoneNone100%
Ramsey CountyZone 1NoneNone100%
Cavalier CountyZone 1NoneNone99.9%
Marshall County, MNZone 1None32.7%67.3%
North Dakota53 counties, pooled by land areaVariesNone1.1%98.9%

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

Local help

Walsh County, Local resources

Radon testing and mitigation in Walsh County

What North Dakota's program says
Phone
701-328-5166
Email
jOtto@nd.gov

What it means

Walsh County, Questions

Questions about radon in Walsh County

Are radon levels high in Walsh County?

Over the 2008 to 2017 laboratory totals, 79.5% of the radon tests reported to CDC for Walsh County, North Dakota were at or above 4 pCi/L, and the median reported pre-mitigation result was 9.8 pCi/L. Of 29 North Dakota counties with 30 or more tests for the same period, 1 reported a higher share; pooled, the state comes to 59.3%.

Which counties border Walsh County?

Walsh County borders 6 counties: Pembina County, ND, Grand Forks County, ND, Nelson County, ND, Ramsey County, ND, Cavalier County, ND and Marshall County, MN.

Products

Walsh County, Products

Testing a home in Walsh County

In Walsh County, 79.5% of 132 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 59.3% pooled across North Dakota. In Zone 1 the year-round level in Walsh 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

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

Explore

Walsh County, Bordering counties

Counties bordering Walsh County

Calculated by Radon411

Walsh County, Cities and towns

Cities and towns in Walsh County

About 10,179 people live in Walsh County by the Census Bureau's estimate for July 1, 2025, 353 fewer than in 2020 (−3.4%). Spread over its land, that is 7.9 people to the square mile. Its largest town, Grafton, has 4,023 residents, 39.5% of the total. Together its 13 incorporated places hold 69.9% of those residents; the other 30.1% live outside any of them. Testing is reported here more often than across the state: CDC's 132 reported tests for 2008 to 2017 come to 13.0 for every 1,000 residents (2025 estimate), against 8.3 for North Dakota.

From Grafton to Conway, CDC publishes no figure by town: each reads Walsh County's.

The 12 largest cities and towns in Walsh County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Grafton4,023−3.3%39.5%
Park River1,363−3.9%13.4%
Minto610−1.3%6.0%
Hoople242−3.6%2.4%
Fordville199−3.4%2.0%
Edinburg193−2.5%1.9%
Adams121−3.2%1.2%
Forest River109+0.9%1.1%
Lankin98−4.9%1.0%
Pisek86−3.4%0.8%
Ardoch31−3.1%0.3%
Fairdale31−3.1%0.3%
  • Conway

13 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).

Walsh County, Homes

Homes in Walsh County

Walsh County is a place of houses on their own lots: 76% of its 5,207 homes are detached single-family houses, against 57% across North Dakota. The homes are older than North Dakota's as a whole: half were built before 1971 (1981 for North Dakota), and 35% date from before 1960. Owners live in 78% of the occupied homes (North Dakota: 63%), so for most households a test and a fix are their own to order.

Homes in Walsh County, North Dakota, 2019 to 2023
HomesWalsh CountyNorth Dakota
Housing units5,207374,866
Detached houses76%57%
In buildings of 5 or more10%25%
Mobile homes7%7%
Built before 196035%24%
Built since 200010%31%
Middle year built19711981
Owner-occupied78%63%

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