Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Roberts County, South Dakota
EPA puts Roberts County in Zone 1, its highest radon zone, and only 26 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
65.8%
Traverse County
- Traverse
- 65.8%
- Richland
- 35.1%
5 of 7 neighbours have 30+ tests, 2006 to 2015
Nearest county
64.6%
Grant County, 33 miles
- Grant
- 64.6%
- SD
- 58.8%
Share at 4+ pCi/L, 82 tests, 2006 to 2015
Ground above low
100.0%
1.0 pts above SD
- Roberts
- 100.0%
- SD
- 99.0%
Share of land USGS rates moderate or high potential
Tests reported
26
Too few for a share
- Roberts
- 26
- 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 Roberts 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
Roberts County, At a glance
Roberts County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Roberts County in
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 Roberts County, 2008 to 2017, laboratory
CDC holds 26 reported tests for Roberts County over the 2008 to 2017 laboratory totals, with a median of 3.8 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Roberts County beside the counties around it is how this page reads it.
What these figures count
Only 26 tests were reported to CDC for Roberts 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).
Roberts County, Compared
Roberts County radon figures, compared
Calculated by Radon411CDC's largest figure for Roberts County rests on 26 tests over the 2008 to 2017 laboratory totals, 12 of them at or above 4 pCi/L, so each test moves its share by 3.8 points and no rank or comparison is drawn from it. Results reached as high as 16.4 pCi/L, with a middle value of 3.8 pCi/L.
Of the counties bordering it, 5 have a figure over the 2006 to 2015 laboratory totals: Traverse County, MN reported the largest share at or above 4 pCi/L, 65.8%, and Richland County, ND the smallest, 35.1%, with Grant County at 64.6%, Big Stone County, MN at 62.9% and Sargent County, ND at 62.5% between. Farther out, Codington County (47 miles away) at 65.3%, Brown County (68 miles away) at 59.6% and Brookings County (87 miles away) at 67.4% 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 Roberts 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.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Roberts County, Geology
The ground under Roberts County
PredictedUSGS's geologic map puts all of Roberts County's mapped land in one class: high radon potential. The map puts 90.8% of Roberts County in the area it calls Missouri Coteau/James River Lowland/Coteau des Prairies and 9.0% in Glacial Lake Agassiz. USGS gives both a radon index of 14, in the high band (12 to 17).
| 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 | 90.8% |
| Glacial Lake Agassiz | Silt and clay glacial lake deposits. | High | 14 | 9.0% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Roberts County beside the ground around it
Roberts County has more high-potential ground than South Dakota as a whole: 100% of its land against 56.7%. Of the 7 counties that border it, none has as large a share of high-potential ground; Big Stone County, MN comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Roberts County, Local resources
Radon testing and mitigation in Roberts 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
Roberts County, Questions
Questions about radon in Roberts County
Are radon levels high in Roberts County?
Over the 2008 to 2017 laboratory totals, 46.2% of the radon tests reported to CDC for Roberts County, South Dakota were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.8 pCi/L. Of the counties bordering it, 5 have a figure over the 2006 to 2015 laboratory totals: Traverse County, MN reported the largest share at or above 4 pCi/L, 65.8%, and Richland County, ND the smallest, 35.1%, with Grant County at 64.6%, Big Stone County, MN at 62.9% and Sargent County, ND at 62.5% between.
Which counties border Roberts County?
Roberts County borders 7 counties: Marshall County, SD, Day County, SD, Traverse County, MN, Grant County, SD, Big Stone County, MN, Sargent County, ND and Richland County, ND.
Products
Roberts County, Products
Testing a home in Roberts County
No CDC figure names Roberts County; the nearest county with one, Grant County (33 miles away), reported 64.6% 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 Roberts 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
Hello Radon C battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
Method: Alpha spectrometry
First reading: Within 24 hours
Short-term kitFirst Alert
RD1 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 2 to 4 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Roberts County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Roberts County
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Roberts County, Bordering counties
Counties bordering Roberts County
Calculated by Radon411- Radon levels in Marshall County, SDEPA zone 1
83.3%at or above 4 pCi/L
Median 10.3 pCi/L · 12 tests
- Radon levels in Traverse County, MNEPA zone 1
65.8%at or above 4 pCi/L
Median 5.3 pCi/L · 73 tests
- Radon levels in Grant County, SDEPA zone 1
64.6%at or above 4 pCi/L
Median 6.0 pCi/L · 82 tests
- Radon levels in Big Stone County, MNEPA zone 1
62.9%at or above 4 pCi/L
Median 4.9 pCi/L · 170 tests
- Radon levels in Sargent County, NDEPA zone 1
62.5%at or above 4 pCi/L
Median 4.8 pCi/L · 40 tests
- Radon levels in Day County, SDEPA zone 1
50.0%at or above 4 pCi/L
Median 4.0 pCi/L · 6 tests
- Radon levels in Richland County, NDEPA zone 1
35.1%at or above 4 pCi/L
Median 3.0 pCi/L · 134 tests
Roberts County, Cities and towns
Cities and towns in Roberts County
Roberts County's population has barely moved since 2020: 10,255 residents on July 1, 2025 against 10,266 then, by the Census Bureau's estimates. Spread over its land, that is 9.3 people to the square mile. Its largest town, Sisseton, has 2,413 residents, 23.5% of the total. Together its 10 incorporated places hold 39.9% of those residents; the other 60.1% live outside any of them. Reported testing is thin here: 26 tests over 2008 to 2017, or 2.5 for every 1,000 residents (2025 estimate), where South Dakota as a whole comes to 6.7.
From Sisseton to White Rock, CDC publishes no figure by town: each reads Roberts County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Sisseton | 2,413 | −2.3% | 23.5% |
| Wilmot | 423 | −2.3% | 4.1% |
| Rosholt | 370 | −2.9% | 3.6% |
| Summit | 276 | −3.2% | 2.7% |
| New Effington | 226 | −3.0% | 2.2% |
| Peever | 172 | −2.3% | 1.7% |
| Claire City | 81 | −2.4% | 0.8% |
| Corona | 72 | +9.1% | 0.7% |
| Ortley | 55 | +7.8% | 0.5% |
| White Rock | 7 | Level | Under 0.1% |
10 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).
Roberts County, Homes
Homes in Roberts County
Roberts County is a place of houses on their own lots: 82% of its 4,823 homes are detached single-family houses, against 67% across South Dakota. Half of its homes were built before 1973, close to South Dakota's 1979: 37% date from before 1960 and 17% from 2000 or later. 69% 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 | Roberts County | South Dakota |
|---|---|---|
| Housing units | 4,823 | 402,364 |
| Detached houses | 82% | 67% |
| In buildings of 5 or more | 4% | 16% |
| Mobile homes | 10% | 8% |
| Built before 1960 | 37% | 29% |
| Built since 2000 | 17% | 28% |
| Middle year built | 1973 | 1979 |
| Owner-occupied | 69% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.