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Radon Levels in Charles Mix County, South Dakota

EPA puts Charles Mix County in Zone 1, its highest radon zone, and only 28 radon tests from it are on file with CDC (2008 to 2017, laboratory totals). 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

  • Highest bordering

    79.5%

    Bon Homme County

    Bon Homme
    79.5%
    Brule
    62.5%

    4 of 9 neighbours have 30+ tests, 2006 to 2015

  • Nearest county

    79.5%

    Bon Homme County, 39 miles

    Bon Homme
    79.5%
    SD
    58.8%

    Share at 4+ pCi/L, 39 tests, 2006 to 2015

  • Ground above low

    100.0%

    1.0 pts above SD

    Charles Mix
    100.0%
    SD
    99.0%

    Share of land USGS rates moderate or high potential

  • Tests reported

    28

    Too few for a share

    Charles Mix
    28
    Needed
    30

    2008 to 2017, laboratory

  • 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

Read a result for Charles Mix 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

Charles Mix County, At a glance

Charles Mix County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Charles Mix 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 Charles Mix County, 2008 to 2017, laboratory

CDC holds 28 reported tests for Charles Mix County over the 2008 to 2017 laboratory totals, with a median of 6.5 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Charles Mix County beside the counties around it is how this page reads it.

What these figures count

Only 28 tests were reported to CDC for Charles Mix County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Charles Mix County, Compared

Charles Mix County radon figures, compared

Calculated by Radon411

CDC's largest figure for Charles Mix County rests on 28 tests over the 2008 to 2017 laboratory totals, 17 of them at or above 4 pCi/L, so each test moves its share by 3.6 points and no rank or comparison is drawn from it. Results reached as high as 39.4 pCi/L, with a middle value of 6.5 pCi/L.

Of the counties bordering it, 4 have a figure over the 2006 to 2015 laboratory totals: Bon Homme County reported the largest share at or above 4 pCi/L, 79.5%, and Brule County the smallest, 62.5%, with Knox County, NE at 70.6% and Boyd County, NE at 63.0% between. Farther out, Davison County (39 miles away) at 47.9%, Yankton County (62 miles away) at 66.3% and Turner County (73 miles away) at 53.3% have figures too. Pooled across 63 South Dakota counties, 58.8% of reported tests reached that level; across every county in the country with a figure, 36.3%.

Statewide for the same period, Bon Homme County reported the highest share (79.5%) and Davison County the lowest (47.9%). EPA's 1993 map puts Charles Mix County in Zone 1, the map's highest label: a predicted county average above 4 pCi/L. USGS geology rates 100% of the county's land high radon potential.

South Dakota, the United States and the counties around Charles Mix County, 2006 to 2015, laboratory
AreaTestsAt or above 4 pCi/LMedian
South Dakota, pooled63 counties, pooled4,89358.8%Not pooled
United States, pooled2,669 counties, pooled1,805,52836.3%Not pooled
Lake Countyhighest in the state3873.7%8.3 pCi/L
Davison Countylowest in the state7147.9%3.7 pCi/L
Lyman County, SDborders it5100.0%20.0 pCi/L
Gregory County, SDborders it1080.0%6.7 pCi/L
Bon Homme County, SDborders it3979.5%8.1 pCi/L
Hutchinson County, SDborders it2576.0%8.2 pCi/L
Knox County, NEborders it38870.6%6.4 pCi/L
Boyd County, NEborders it4663.0%5.3 pCi/L
Brule County, SDborders it3262.5%6.3 pCi/L
Aurora County, SDborders it1040.0%2.3 pCi/L
Douglas County, SDborders it30.0%1.3 pCi/L
The nearest South Dakota counties to Charles Mix County with 30 or more tests, 2006 to 2015, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
Bon Homme County39 mi3979.5%8.1 pCi/L
Davison County39 mi7147.9%3.7 pCi/L
Brule County43 mi3262.5%6.3 pCi/L
Yankton County62 mi8066.3%5.4 pCi/L
Turner County73 mi4553.3%4.0 pCi/L
Clay County84 mi6056.7%5.0 pCi/L
Beadle County85 mi4663.0%5.6 pCi/L
Lake County92 mi3873.7%8.3 pCi/L
Charles Mix County ten-year laboratory totals, against South Dakota's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestSouth Dakota, pooledChange from the row before
2008 to 20172860.7%6.5 pCi/L39.4 pCi/L58.5%+6.9 points
2007 to 20161353.8%5.4 pCi/L13.7 pCi/L57.4%−9.8 points
2006 to 20151163.6%6.1 pCi/L13.7 pCi/L58.8%−6.4 points
2005 to 20141070.0%7.6 pCi/L13.7 pCi/L59.6%First on file

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

Charles Mix County, Geology

The ground under Charles Mix County

Predicted

Most of the ground under Charles Mix County is one class on USGS's geologic map: 99.8% of its land is high radon potential, with 0.2% moderate. All of it lies in the area the map calls Missouri Coteau/James River Lowland/Coteau des Prairies, to which USGS gives a radon index of 14, in the high band (12 to 17).

USGS's geologic areas under Charles Mix County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Missouri Coteau/James River Lowland/Coteau des PrairiesGlacial drift derived largely from Cretaceous marine shale.High1499.7%

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

Charles Mix County beside the ground around it

Charles Mix County has more high-potential ground than South Dakota as a whole: 99.8% of its land against 56.7%. Of the 9 counties that border it, 5 have more high-potential ground, Aurora County the most at 100%.

Share of land by USGS radon potential: Charles Mix County, the 9 counties bordering it and South Dakota
AreaEPA zoneLow potentialModerate potentialHigh potential
Charles Mix CountyZone 1None0.2%99.8%
Douglas CountyZone 1NoneNone100%
Boyd County, NEZone 1None4.9%95.1%
Bon Homme CountyZone 1NoneNone100%
Aurora CountyZone 1NoneNone100%
Hutchinson CountyZone 1NoneNone100%
Gregory CountyZone 2None92.9%7.1%
Knox County, NEZone 1None20.0%80.0%
Brule CountyZone 1NoneNone100%
Lyman CountyZone 1None44.3%55.7%
South Dakota66 counties, pooled by land areaVaries1.0%42.3%56.7%

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

Local help

Charles Mix County, Local resources

Radon testing and mitigation in Charles Mix County

What South Dakota's program says
Phone
1-800-438-3367

What it means

Charles Mix County, Questions

Questions about radon in Charles Mix County

Are radon levels high in Charles Mix County?

Over the 2008 to 2017 laboratory totals, 60.7% of the radon tests reported to CDC for Charles Mix County, South Dakota were at or above 4 pCi/L, and the median reported pre-mitigation result was 6.5 pCi/L. Of the counties bordering it, 4 have a figure over the 2006 to 2015 laboratory totals: Bon Homme County reported the largest share at or above 4 pCi/L, 79.5%, and Brule County the smallest, 62.5%, with Knox County, NE at 70.6% and Boyd County, NE at 63.0% between.

Which counties border Charles Mix County?

Charles Mix County borders 9 counties: Douglas County, SD, Boyd County, NE, Bon Homme County, SD, Aurora County, SD, Hutchinson County, SD, Gregory County, SD, Knox County, NE, Brule County, SD and Lyman County, SD.

Products

Charles Mix County, Products

Testing a home in Charles Mix County

No CDC figure names Charles Mix County; the nearest county with one, Bon Homme County (39 miles away), reported 79.5% of its tests at or above 4 pCi/L over the 2006 to 2015 laboratory totals, the only reading nearby until a test of this home. In Zone 1 the year-round level in Charles Mix 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

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

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Charles Mix County, Bordering counties

Counties bordering Charles Mix County

Calculated by Radon411

Charles Mix County, Cities and towns

Cities and towns in Charles Mix County

About 9,303 people live in Charles Mix County by the Census Bureau's estimate for July 1, 2025, 50 fewer than in 2020 (−0.5%). Spread over its land, that is 8.5 people to the square mile. No town dominates: Wagner, the largest, has 1,422 residents, 15.3% of the total. Together its 7 incorporated places hold 41.7% of those residents; the other 58.3% live outside any of them. Reported testing is thin here: 28 tests over 2008 to 2017, or 3.0 for every 1,000 residents (2025 estimate), where South Dakota as a whole comes to 6.7.

From Wagner to Ravinia, CDC publishes no figure by town: each reads Charles Mix County's.

The cities and towns in Charles Mix County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Wagner1,422−4.4%15.3%
Platte1,230−4.4%13.2%
Lake Andes687−3.9%7.4%
Pickstown248+8.8%2.7%
Geddes150−3.8%1.6%
Dante71+1.4%0.8%
Ravinia71+2.9%0.8%

7 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).

Charles Mix County, Homes

Homes in Charles Mix County

Charles Mix County is a place of houses on their own lots: 85% of its 3,664 homes are detached single-family houses, against 67% across South Dakota. The homes are older than South Dakota's as a whole: half were built before 1969 (1979 for South Dakota), and 43% date from before 1960. 74% of occupied homes are lived in by their owner (South Dakota: 69%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Charles Mix County, South Dakota, 2019 to 2023
HomesCharles Mix CountySouth Dakota
Housing units3,664402,364
Detached houses85%67%
In buildings of 5 or more6%16%
Mobile homes6%8%
Built before 196043%29%
Built since 200016%28%
Middle year built19691979
Owner-occupied74%69%

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