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Radon Levels in Richland County, North Dakota

EPA puts Richland County in Zone 1, its highest radon zone, and high results are common there: 43.0% of the 93 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

    43.0%

    16.3 pts below ND

    Richland
    43.0%
    ND
    59.3%

    93 tests, 2008 to 2017

  • Median result

    3.6pCi/L

    Below action level

    Richland
    3.6 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    93

    14th of 29 by tests

    Richland
    93
    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

    28 of 29

    Lowest quarter

    Richland
    43.0%
    Pembina
    82.5%

    By share, of 29 with 30+ tests

Read a result for Richland County

Starts at Richland County's median, 3.6 pCi/L

3.6pCi/L

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

EPA’s reading of 3.6 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. Richland County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Richland County, At a glance

Richland County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

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

Reported results by concentration band, Richland County, 2008 to 2017, laboratory
Under 2 pCi/L: 24%2 to 4 pCi/L: 33%4 pCi/L and above: 43%

Of 93 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Richland County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L2223.7%
2 to 4 pCi/L3133.3%
4 pCi/L and above4043.0%
What these figures count

These are the 93 tests reported to CDC for Richland 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

Richland County, Compared

Richland County radon figures, compared

Calculated by Radon411

In Richland County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (40 of 93) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 7.3 points higher. Across 53 North Dakota counties pooled together, 59.3% of tests reached that level, so Richland County runs 16.3 points below its state.

Of 5 neighbours with a figure, 4 reported a larger share at or above 4 pCi/L and 1 a smaller one; the spread is 41.8% (Wilkin County, MN) to 61.6% (Ransom County). By share, Richland County is 28th of 29 North Dakota counties with 30 or more tests for the same period.

Half the tests came in under 3.6 pCi/L and half over it; the single highest reached 36.4 pCi/L. Below the action level, 22 tests (23.7%) came in under 2 pCi/L, against 18.3% statewide, and 31 tests (33.3%) fell between 2 and 4, against 22.4% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 43.0% share point the same way here. USGS geology rates 100% of the county's land high radon potential.

CDC's ten-year totals for Richland County went from 137 tests (2005 to 2014) to 93 (2008 to 2017), the share going from 37.2% to 43.0%.

Richland County against North Dakota, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Richland County
Richland County9343.0%3.6 pCi/LThis county
North Dakota, pooled53 counties, pooled6,60759.3%Not pooled+16.3 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−7.3 points
Pembina Countyhighest in the state5782.5%9.3 pCi/L+39.5 points
Williams Countylowest in the state20433.8%2.9 pCi/L−9.2 points
Marshall County, SDborders it1681.3%10.5 pCi/L+38.3 points
Sargent County, NDborders it2475.0%7.2 pCi/L+32.0 points
Ransom County, NDborders it15161.6%5.8 pCi/L+18.6 points
Clay County, MNborders it46561.5%5.6 pCi/L+18.5 points
Cass County, NDborders it86257.5%4.7 pCi/L+14.5 points
Traverse County, MNborders it6256.5%4.8 pCi/L+13.5 points
Roberts County, SDborders it2646.2%3.8 pCi/L+3.2 points
Wilkin County, MNborders it7941.8%3.3 pCi/L−1.2 points
Where Richland County's reported results fell, 2008 to 2017, laboratory, beside North Dakota and the United States
ResultRichland County testsRichland County shareNorth Dakota shareU.S. shareAgainst North Dakota
Under 2 pCi/L2223.7%18.3%39.6%+5.4 points
2 to 4 pCi/L3133.3%22.4%24.7%+10.9 points
4 pCi/L and above4043.0%59.3%35.7%−16.3 points
Richland 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
Foster County19 of 293161.3%4.5 pCi/L
Cass County20 of 2986257.5%4.7 pCi/L
McKenzie County21 of 294156.1%4.8 pCi/L
Morton County22 of 2926853.4%4.2 pCi/L
Traill County23 of 293751.4%4.1 pCi/L
Burleigh County24 of 291,55851.1%4.0 pCi/L
Pierce County25 of 293948.7%3.8 pCi/L
Wells County26 of 298148.1%3.8 pCi/L
Ward County27 of 2944643.0%3.3 pCi/L
Richland County28 of 299343.0%3.6 pCi/L
Williams County29 of 2920433.8%2.9 pCi/L
Richland 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 20179343.0%3.6 pCi/L36.4 pCi/L59.3%+4.0 points
2007 to 201611839.0%3.3 pCi/L36.4 pCi/L58.7%+3.9 points
2006 to 201513435.1%3.0 pCi/L36.4 pCi/L56.3%−2.1 points
2005 to 201413737.2%3.0 pCi/L36.4 pCi/L54.0%First on file

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

Richland County, Geology

The ground under Richland County

Predicted

USGS's geologic map puts all of Richland County's mapped land in one class: high radon potential. The map puts 89.2% of Richland County in the area it calls Glacial Lakes and 10.6% 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 Richland 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.High1489.2%
Great Plains (Glaciated)Glacial deposits derived from Cretaceous shales containing higher than average amounts of uranium.High1310.6%

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

Richland County beside the ground around it

On high-potential ground Richland County is close to North Dakota as a whole: 100% of its land against 98.9%. Of the 8 counties that border it, none has as large a share of high-potential ground; Marshall County, SD comes nearest at 100%.

Share of land by USGS radon potential: Richland County, the 8 counties bordering it and North Dakota
AreaEPA zoneLow potentialModerate potentialHigh potential
Richland CountyZone 1NoneNone100%
Wilkin County, MNZone 1NoneNone100%
Sargent CountyZone 1NoneNone100%
Ransom CountyZone 1NoneNone100%
Traverse County, MNZone 1NoneNone100%
Clay County, MNZone 1NoneNone100%
Cass CountyZone 1NoneNone100%
Roberts County, SDZone 1NoneNone100%
Marshall County, SDZone 1NoneNone100%
North Dakota53 counties, pooled by land areaVariesNone1.1%98.9%

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

Local help

Richland County, Local resources

Radon testing and mitigation in Richland County

Listed radon businesses with an address in Richland County:

Listed radon professionals by town: Wahpeton

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

What it means

Richland County, Questions

Questions about radon in Richland County

Are radon levels high in Richland County?

Over the 2008 to 2017 laboratory totals, 43.0% of the radon tests reported to CDC for Richland County, North Dakota were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.6 pCi/L. Of 29 North Dakota counties with 30 or more tests for the same period, 27 reported a higher share; pooled, the state comes to 59.3%.

Which counties border Richland County?

Richland County borders 8 counties: Wilkin County, MN, Sargent County, ND, Ransom County, ND, Traverse County, MN, Clay County, MN, Cass County, ND, Roberts County, SD and Marshall County, SD.

Products

Richland County, Products

Testing a home in Richland County

In Richland County, 43.0% of 93 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 Richland 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

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

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Richland County, Bordering counties

Counties bordering Richland County

Calculated by Radon411

Richland County, Cities and towns

Cities and towns in Richland County

The Census Bureau estimates 16,731 residents in Richland County for July 1, 2025, 193 more than in 2020 (+1.2%). That works out to 12 people per square mile of land. Its largest town, Wahpeton, has 8,141 residents, 48.7% of the total. Together its 14 incorporated places hold 70.3% of those residents; the other 29.7% live outside any of them. CDC's 93 reported tests for 2008 to 2017 work out to 5.6 per 1,000 residents (2025 estimate), close to North Dakota's 8.3.

From Wahpeton to Barney, CDC publishes no figure by town: each reads Richland County's.

The 12 largest cities and towns in Richland County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Wahpeton8,141+1.6%48.7%
Hankinson936+1.7%5.6%
Lidgerwood585−2.3%3.5%
Wyndmere442−1.3%2.6%
Fairmount331−3.2%2.0%
Abercrombie269+10.2%1.6%
Walcott268+1.5%1.6%
Colfax217+28.4%1.3%
Mooreton177−2.2%1.1%
Christine149−2.0%0.9%
Dwight77−2.5%0.5%
Mantador68Level0.4%
  • Great Bend
  • Barney

14 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).

Richland County, Homes

Homes in Richland County

Of Richland County's 7,552 homes, 69% are detached houses, against 57% across North Dakota; 22% are in buildings of five or more homes. The homes are older than North Dakota's as a whole: half were built before 1972 (1981 for North Dakota), and 34% date from before 1960. 69% of occupied homes are lived in by their owner (North Dakota: 63%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Richland County, North Dakota, 2019 to 2023
HomesRichland CountyNorth Dakota
Housing units7,552374,866
Detached houses69%57%
In buildings of 5 or more22%25%
Mobile homes4%7%
Built before 196034%24%
Built since 200016%31%
Middle year built19721981
Owner-occupied69%63%

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