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 Valley County, Montana
EPA puts Valley County in Zone 1, its highest radon zone, and only 24 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
Share at 4+ pCi/L
50.0%
2.6 pts above MT
- Valley
- 50.0%
- Montana
- 47.4%
40 tests, 2006 to 2015
Median result
4.2pCi/L
Action level reached
- Valley
- 4.2 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2006 to 2015
Tests reported
40
23rd of 24 by tests
- Valley
- 40
- Missoula
- 2,122
Reported to CDC before any fix, 2006 to 2015
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Montana
14 of 24
Middle half
- Valley
- 50.0%
- Sheridan
- 75.7%
By share, of 24 with 30+ tests
Read a result for Valley County
Starts at Valley County's median, 4.2 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.2 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. Valley County's median reported result, 2006 to 2015.
The data
Valley County, At a glance
Valley County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Valley 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 Valley County, 2008 to 2017, laboratory
CDC holds 24 reported tests for Valley County over the 2008 to 2017 laboratory totals, with a median of 4.5 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Valley County beside the counties around it is how this page reads it.
What these figures count
Only 24 tests were reported to CDC for Valley 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).
Valley County, Compared
Valley County radon figures, compared
Calculated by Radon411More than half: 50.0% of the 40 radon tests reported to CDC for Valley County over the 2006 to 2015 laboratory totals read at least 4 pCi/L. That places it 14th of 24 Montana counties with 30 or more tests for the same period. That is 2.6 points above the 47.4% pooled from 52 Montana counties.
The newest figure, over the 2008 to 2017 laboratory totals, counts only 24 tests (54.2% at or above 4 pCi/L), too few to compare, so this reading uses the 40-test figure.
The median result, 4.2 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 81.1 pCi/L. The rest split 20.0% under 2 pCi/L and 30.0% from 2 to 4 (Montana: 27.8% and 24.8%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 50.0% share point the same way here.
Statewide for the same period, Sheridan County reported the highest share (75.7%) and Hill County the lowest (35.0%).
CDC's ten-year totals for Valley County went from 39 tests (2005 to 2014) to 24 (2008 to 2017), the share going from 51.3% to 54.2%.
Nationally, every county with a figure for the same period pools to 36.3%; Valley County sits 13.7 points above it.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Valley County, Geology
The ground under Valley County
PredictedUSGS's geologic map puts all of Valley County's mapped land in one class: high radon potential. All of it lies in the area the map calls Great Plains (Glaciated), to which USGS gives a radon index of 13, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Great Plains (Glaciated) | Glacial deposits derived from Cretaceous shales containing higher than average amounts of uranium. | High | 13 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Valley County beside the ground around it
Valley County has more high-potential ground than Montana as a whole: 100% of its land against 78.5%. Of the 5 counties that border it, none has as large a share of high-potential ground; Daniels County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Valley County, Local resources
Radon testing and mitigation in Valley County
- Radon Control ProgramRadon Control Program, run by Montana DEQ, does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Montana.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Energy Bureau staff manage the radon information toll-free hotline and distribute subsidized radon test kits to Montana residents.
- Compare kits
- See the Montana directoryNo professionals are listed in Montana yet. The state program can point you to registered testers and mitigators.
What Montana's program says
- Phone
- 1-800-546-0483
- Licensing of radon professionals
Montana DEQ does not certify or require proof of certification for the contractors listed.
What it means
Valley County, Questions
Questions about radon in Valley County
Are radon levels high in Valley County?
Over the 2008 to 2017 laboratory totals, 54.2% of the radon tests reported to CDC for Valley County, Montana were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.5 pCi/L. Of 24 Montana counties with 30 or more tests for the same period, 13 reported a higher share; pooled, the state comes to 47.4%.
Which counties border Valley County?
Valley County borders 5 counties: Daniels County, McCone County, Phillips County, Garfield County and Roosevelt County.
Products
Valley County, Products
Testing a home in Valley County
In Valley County, 50.0% of 40 tests reported to CDC over the 2006 to 2015 laboratory totals reached 4 pCi/L, against 47.4% pooled across Montana. In Zone 1 the year-round level in Valley 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
Wave Plus battery radon and air quality monitor
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- App only
Method: Alpha spectrometry
Short-term kitempowerDX
Standard Radon Test short-term mail-in radon test kit
- Lab fee included
Method: Passive sampler
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Valley County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Valley County
Explore
Valley County, Bordering counties
Counties bordering Valley County
Calculated by Radon411- Radon levels in Phillips CountyEPA zone 1
100.0%at or above 4 pCi/L
Median 6.2 pCi/L · 2 tests · 50.0 points above Valley County
- Radon levels in Roosevelt CountyEPA zone 1
93.8%at or above 4 pCi/L
Median 9.3 pCi/L · 16 tests · 43.8 points above Valley County
- Radon levels in McCone CountyEPA zone 1
25.0%at or above 4 pCi/L
Median 2.5 pCi/L · 4 tests · 25.0 points below Valley County
- Radon levels in Daniels CountyEPA zone 1
0.0%at or above 4 pCi/L
Median 2.3 pCi/L · 4 tests · 50.0 points below Valley County
- Radon levels in Garfield CountyEPA zone 1
No CDC figure for 2006 to 2015; its page reads it against its own neighbours.
Valley County, Cities and towns
Cities and towns in Valley County
About 7,385 people live in Valley County by the Census Bureau's estimate for July 1, 2025, 179 fewer than in 2020 (−2.4%). Spread over its land, that is 1.5 people to the square mile. Its largest town, Glasgow, has 3,145 residents, 42.6% of the total. Together its 4 incorporated places hold 50.7% of those residents; the other 49.3% live outside any of them. CDC's 40 reported tests for 2006 to 2015 work out to 5.4 per 1,000 residents (2025 estimate), close to Montana's 7.5.
From Glasgow to Opheim, CDC publishes no figure by town: each reads Valley County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Glasgow | 3,145 | −1.7% | 42.6% |
| Nashua | 292 | −2.7% | 4.0% |
| Fort Peck | 232 | −2.5% | 3.1% |
| Opheim | 73 | −2.7% | 1.0% |
4 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).
Valley County, Homes
Homes in Valley County
Of Valley County's 4,253 homes, 68% are detached houses, against 69% across Montana; 5% are mobile homes. The homes are older than Montana's as a whole: half were built before 1966 (1980 for Montana), and 34% date from before 1960. Owners live in 78% of the occupied homes (Montana: 69%), so for most households a test and a fix are their own to order.
| Homes | Valley County | Montana |
|---|---|---|
| Housing units | 4,253 | 522,939 |
| Detached houses | 68% | 69% |
| In buildings of 5 or more | 5% | 9% |
| Mobile homes | 5% | 10% |
| Built before 1960 | 34% | 26% |
| Built since 2000 | 6% | 27% |
| Middle year built | 1966 | 1980 |
| Owner-occupied | 78% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.