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Radon Levels in Wahkiakum County, Washington

EPA puts Wahkiakum County in Zone 3, its lowest radon zone, and only 1 radon test from it is on file with CDC (2020). Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

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  • Highest bordering

    40.0%

    Clatsop County

    Clatsop
    40.0%
    Cowlitz
    11.3%

    3 of 5 neighbours have 30+ tests, 2008 to 2017

  • Nearest county

    11.3%

    Cowlitz County, 36 miles

    Cowlitz
    11.3%
    Washington
    25.5%

    Share at 4+ pCi/L, 62 tests, 2008 to 2017

  • Ground above low

    None

    52.7 pts below Washington

    Wahkiakum
    0.0%
    Washington
    52.7%

    Share of land USGS rates moderate or high potential

  • Tests reported

    5

    Too few for a share

    Wahkiakum
    5
    Needed
    30

    2016

  • EPA radon zone

    Zone 3

    Lower potential

    1. 1
    2. 2
    3. Zone 3

    1 highest, 3 lowest

    EPA predicts under 2 pCi/L indoors

Read a result for Wahkiakum County

Starts at EPA's action level

4.0pCi/L

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

EPA’s reading of 4.0 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.

Interpret this readingWhat a fix costs

The data

Wahkiakum County, At a glance

Wahkiakum County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Wahkiakum County as a whole is an average indoor of less than 2 pCi/L (less than 75 Bq/m³). A low zone clears no address in it: homes above EPA's turn up in all three zones.

USGS geologic potential: Low across 92% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Wahkiakum County, 2020

Share of reported tests at or above 4 pCi/L, by year, Wahkiakum County
Share of reported tests at or above 4 pCi/L, by year, Wahkiakum County
YearShare of reported tests at or above 4 pCi/L
20140.0%
20160.0%
20200.0%

2020: 0.0%. Across these years the share ran from 0.0% to 0.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 1 test was reported to CDC for Wahkiakum County over 2020, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.

Measured: CDC tracking data. Figure above: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).

How to read these figures

Wahkiakum County, Compared

Wahkiakum County radon figures, compared

Calculated by Radon411

CDC's largest figure for Wahkiakum County rests on 5 tests in 2016, 0 of them at or above 4 pCi/L, so each test moves its share by 20.0 points and no rank or comparison is drawn from it. Results reached as high as 2.6 pCi/L, with a middle value of 0.1 pCi/L.

Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Clatsop County, OR reported the largest share at or above 4 pCi/L, 40.0%, and Cowlitz County the smallest, 11.3%, with Columbia County, OR at 36.8% between. Farther out, Thurston County (52 miles away) at 10.1%, Clark County (57 miles away) at 25.1% and Skamania County (75 miles away) at 39.7% have figures too. Pooled across 39 Washington counties, 25.5% of reported tests reached that level; across every county in the country with a figure, 35.7%.

Statewide for the same period, Pend Oreille County reported the highest share (63.2%) and Snohomish County the lowest (2.3%). EPA's 1993 map puts Wahkiakum County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 92% of the county's land low radon potential.

Washington, the United States and the counties around Wahkiakum County, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedian
Washington, pooled39 counties, pooled8,20125.5%Not pooled
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled
Pend Oreille Countyhighest in the state3863.2%4.8 pCi/L
Snohomish Countylowest in the state2652.3%0.5 pCi/L
Clatsop County, ORborders it5540.0%3.0 pCi/L
Columbia County, ORborders it21236.8%1.9 pCi/L
Cowlitz County, WAborders it6211.3%1.1 pCi/L
Lewis County, WAborders it119.1%0.1 pCi/L
Pacific County, WAborders it20.0%0.5 pCi/L
The nearest Washington counties to Wahkiakum County with 30 or more tests, 2008 to 2017, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
Cowlitz County36 mi6211.3%1.1 pCi/L
Thurston County52 mi19810.1%0.7 pCi/L
Clark County57 mi1,81425.1%1.8 pCi/L
Skamania County75 mi6839.7%2.9 pCi/L
Pierce County81 mi2264.9%0.7 pCi/L
Kitsap County98 mi824.9%0.7 pCi/L
King County113 mi1,2672.6%0.7 pCi/L
Yakima County129 mi807.5%0.7 pCi/L
Wahkiakum County radon tests by year, against Washington's pooled share
YearTestsAt or above 4 pCi/LMedianHighestWashington, pooledChange from the row before
202010.0%0.1 pCi/L0.1 pCi/L19.0%Level
201650.0%0.1 pCi/L2.6 pCi/L16.6%Level
201410.0%0.1 pCi/L0.1 pCi/L15.0%First on file

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

Wahkiakum County, Geology

The ground under Wahkiakum County

Predicted

USGS's geologic map puts all of Wahkiakum County's mapped land in one class: low radon potential. 92.5% of it lies in the area the map calls Coastal Hills, to which USGS gives a radon index of 6, in the low band (5 to 8).

USGS's geologic areas under Wahkiakum County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Coastal HillsCretaceous and Tertiary continental and marine sedimentary rocks and pre-Miocene volcanic rocks.Low692.5%

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

Wahkiakum County beside the ground around it

Across Washington 13.7% of the land is rated high; none of Wahkiakum County's is. Of the 5 counties that border it, 3 have more moderate-potential ground, Columbia County, OR the most at 91.6%.

Share of land by USGS radon potential: Wahkiakum County, the 5 counties bordering it and Washington
AreaEPA zoneLow potentialModerate potentialHigh potential
Wahkiakum CountyZone 392.5%NoneNone
Pacific CountyZone 397.4%NoneNone
Clatsop County, ORZone 231.1%63.3%None
Columbia County, ORZone 24.2%91.6%None
Cowlitz CountyZone 396.6%2.1%None
Lewis CountyZone 3100%NoneNone
Washington38 counties, pooled by land areaVaries46.4%39.0%13.7%

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

Local help

Wahkiakum County, Local resources

Radon testing and mitigation in Wahkiakum County

What Washington's program says
Phone
360-236-3200
Email
doh.radon@doh.wa.gov

What it means

Wahkiakum County, Questions

Questions about radon in Wahkiakum County

Are radon levels high in Wahkiakum County?

In 2020, 0.0% of the radon tests reported to CDC for Wahkiakum County, Washington were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.1 pCi/L. Of the counties bordering it, 3 have a figure over the 2008 to 2017 laboratory totals: Clatsop County, OR reported the largest share at or above 4 pCi/L, 40.0%, and Cowlitz County the smallest, 11.3%, with Columbia County, OR at 36.8% between.

Which counties border Wahkiakum County?

Wahkiakum County borders 5 counties: Pacific County, WA, Clatsop County, OR, Columbia County, OR, Cowlitz County, WA and Lewis County, WA.

Products

Wahkiakum County, Products

Testing a home in Wahkiakum County

No CDC figure names Wahkiakum County; the nearest county with one, Cowlitz County (36 miles away), reported 11.3% of its tests at or above 4 pCi/L over the 2008 to 2017 laboratory totals, the only reading nearby until a test of this home. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Wahkiakum County.

Test kits and monitors3

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Best radon monitors for Wahkiakum County homes, compared

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Wahkiakum County, Bordering counties

Counties bordering Wahkiakum County

Calculated by Radon411

Wahkiakum County, Cities and towns

Cities and towns in Wahkiakum County

Wahkiakum County is growing: the Census Bureau puts it at 4,873 residents on July 1, 2025, up 9.6% from 4,446 in 2020. That works out to 19 people per square mile of land. Cathlamet, its one incorporated place, has 610 residents, 12.5% of the total. Testing is reported here more often than across the state: CDC's 5 reported tests for 2016 come to 1.0 for every 1,000 residents (2025 estimate), against 0.6 for Washington.

Cathlamet is the one incorporated place here; CDC publishes no figure by town, so it reads Wahkiakum County's.

Cathlamet, Wahkiakum County: residents on July 1, 2025
PlaceResidentsSince 2020Share of residents
Cathlamet610+9.1%12.5%

One incorporated place, 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).

Wahkiakum County, Homes

Homes in Wahkiakum County

Wahkiakum County is a place of houses on their own lots: 84% of its 2,207 homes are detached single-family houses, against 62% across Washington. Half of its homes were built before 1979, close to Washington's 1984: 33% date from before 1960 and 24% from 2000 or later. Owners live in 85% of the occupied homes (Washington: 64%), so for most households a test and a fix are their own to order.

Homes in Wahkiakum County, Washington, 2019 to 2023
HomesWahkiakum CountyWashington
Housing units2,2073,262,667
Detached houses84%62%
In buildings of 5 or more1%22%
Mobile homes13%6%
Built before 196033%21%
Built since 200024%28%
Middle year built19791984
Owner-occupied85%64%

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