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 Stanley County, South Dakota
EPA puts Stanley County in Zone 1, its highest radon zone, and only 3 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
Highest bordering
66.7%
Hughes County
- Hughes
- 66.7%
1 of 7 neighbours have 30+ tests, 2006 to 2015
Nearest county
66.7%
Hughes County, 37 miles
- Hughes
- 66.7%
- SD
- 58.8%
Share at 4+ pCi/L, 30 tests, 2006 to 2015
Ground above low
100.0%
1.0 pts above SD
- Stanley
- 100.0%
- SD
- 99.0%
Share of land USGS rates moderate or high potential
Tests reported
3
Too few for a share
- Stanley
- 3
- Needed
- 30
2008 to 2017, laboratory
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Read a result for Stanley County
Starts at EPA's action level
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
- 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.
The data
Stanley County, At a glance
Stanley County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Stanley County in
USGS geologic potential: High across 54% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Stanley County, 2008 to 2017, laboratory
CDC holds 3 reported tests for Stanley County over the 2008 to 2017 laboratory totals, with a median of 4.2 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Stanley County beside the counties around it is how this page reads it.
What these figures count
Only 3 tests were reported to CDC for Stanley 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).
Stanley County, Compared
Stanley County radon figures, compared
Calculated by Radon411CDC's largest figure for Stanley County rests on 3 tests over the 2008 to 2017 laboratory totals, 2 of them at or above 4 pCi/L, so each test moves its share by 33.3 points and no rank or comparison is drawn from it. Results reached as high as 6.2 pCi/L, with a middle value of 4.2 pCi/L.
Hughes County, the one bordering county with a figure over the 2006 to 2015 laboratory totals, reported 66.7% of its tests at or above 4 pCi/L. Farther out, Brule County (95 miles away) at 62.5%, Meade County (98 miles away) at 54.5% and Edmunds County (102 miles away) at 61.8% 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 Stanley County in Zone 1, the map's highest label: a predicted county average above 4 pCi/L. USGS geology rates 54% of the county's land high radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Stanley County, Geology
The ground under Stanley County
PredictedUSGS's geologic map splits Stanley County: 54.0% of its land is high radon potential and 46.0% moderate. The map puts 54.0% of Stanley County in the area it calls Missouri Coteau/James River Lowland/Coteau des Prairies and 46.0% in Pierre Hills. USGS gives the first a radon index of 14, in the high band (12 to 17), and the second 10, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Missouri Coteau/James River Lowland/Coteau des Prairies | Glacial drift derived largely from Cretaceous marine shale. | High | 14 | 54.0% |
| Pierre Hills | Pierre Shale and Fox Hills sandstone. | Moderate | 10 | 46.0% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Stanley County beside the ground around it
On high-potential ground Stanley County is close to South Dakota as a whole: 54.0% of its land against 56.7%. Of the 7 counties that border it, 3 have more high-potential ground, Hughes County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Stanley County, Local resources
Radon testing and mitigation in Stanley County
- South Dakota's radon programDepartment of Agriculture and Natural ResourcesSouth Dakota's radon program offers free or discounted test kits, and answers questions about testing and mitigation in South Dakota.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
The Department of Agriculture and Natural Resources (DANR) will provide 500 free Radon test kits to South Dakota Residents.
- Compare kits
- Professionals in South Dakota5 professionals are listed in South Dakota.
What South Dakota's program says
- Phone
- 1-800-438-3367
What it means
Stanley County, Questions
Questions about radon in Stanley County
Are radon levels high in Stanley County?
Over the 2008 to 2017 laboratory totals, 66.7% of the radon tests reported to CDC for Stanley County, South Dakota were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.2 pCi/L. Hughes County, the one bordering county with a figure over the 2006 to 2015 laboratory totals, reported 66.7% of its tests at or above 4 pCi/L.
Which counties border Stanley County?
Stanley County borders 7 counties: Haakon County, Jones County, Sully County, Dewey County, Ziebach County, Hughes County and Lyman County.
Products
Stanley County, Products
Testing a home in Stanley County
No CDC figure names Stanley County; the nearest county with one, Hughes County (37 miles away), reported 66.7% 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 Stanley 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
Corentium Home battery digital radon detector
- C-NRPP 2024/25: Approved
- Battery
- Screen
Method: Alpha spectrometry
Short-term kit
RA400 short-term liquid scintillation radon test kit, lab fee included
- Lab fee included
Method: Liquid scintillation
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Stanley County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Stanley County
Explore
Stanley County, Bordering counties
Counties bordering Stanley County
Calculated by Radon411- Radon levels in Jones CountyEPA zone 2
100.0%at or above 4 pCi/L
Median 26.4 pCi/L · 5 tests
- Radon levels in Sully CountyEPA zone 1
100.0%at or above 4 pCi/L
Median 4.1 pCi/L · 1 test
- Radon levels in Ziebach CountyEPA zone 2
100.0%at or above 4 pCi/L
Median 11.6 pCi/L · 3 tests
- Radon levels in Lyman CountyEPA zone 1
100.0%at or above 4 pCi/L
Median 20.0 pCi/L · 5 tests
- Radon levels in Hughes CountyEPA zone 1
66.7%at or above 4 pCi/L
Median 5.5 pCi/L · 30 tests
- Radon levels in Haakon CountyEPA zone 2
50.0%at or above 4 pCi/L
Median 6.3 pCi/L · 2 tests
- Radon levels in Dewey CountyEPA zone 2
0.0%at or above 4 pCi/L
Median 0.6 pCi/L · 1 test
Stanley County, Cities and towns
Cities and towns in Stanley County
The Census Bureau estimates 3,018 residents in Stanley County for July 1, 2025, 52 more than in 2020 (+1.8%). Spread over its land, that is 2.1 people to the square mile. Fort Pierre, its one incorporated place, has 2,166 residents, 71.8% of the total. Reported testing is thin here: 3 tests over 2008 to 2017, or 1.0 for every 1,000 residents (2025 estimate), where South Dakota as a whole comes to 6.7.
Fort Pierre is the one incorporated place here; CDC publishes no figure by town, so it reads Stanley County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Fort Pierre | 2,166 | +2.5% | 71.8% |
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).
Stanley County, Homes
Homes in Stanley County
Of Stanley County's 1,541 homes, 61% are detached houses, against 67% across South Dakota; 24% are mobile homes. Much of Stanley County is recent building: 33% of its homes have gone up since 2000 and the middle year built is 1993, against 1979 for South Dakota. Owners live in 79% of the occupied homes (South Dakota: 69%), so for most households a test and a fix are their own to order.
| Homes | Stanley County | South Dakota |
|---|---|---|
| Housing units | 1,541 | 402,364 |
| Detached houses | 61% | 67% |
| In buildings of 5 or more | 9% | 16% |
| Mobile homes | 24% | 8% |
| Built before 1960 | 15% | 29% |
| Built since 2000 | 33% | 28% |
| Middle year built | 1993 | 1979 |
| Owner-occupied | 79% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.