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 Broadwater County, Montana
EPA puts Broadwater County in Zone 1, its highest radon zone, and only 25 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
66.1%
Jefferson County
- Jefferson
- 66.1%
- Gallatin
- 48.8%
3 of 4 neighbours have 30+ tests, 2006 to 2015
Nearest county
66.1%
Jefferson County, 31 miles
- Jefferson
- 66.1%
- Montana
- 47.4%
Share at 4+ pCi/L, 62 tests, 2006 to 2015
Ground above low
100.0%
Level with Montana
- Broadwater
- 100.0%
- Montana
- 100.0%
Share of land USGS rates moderate or high potential
Tests reported
25
Too few for a share
- Broadwater
- 25
- 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 Broadwater 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
Broadwater County, At a glance
Broadwater County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Broadwater 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 Broadwater County, 2008 to 2017, laboratory
CDC holds 25 reported tests for Broadwater County over the 2008 to 2017 laboratory totals, with a median of 4.1 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Broadwater County beside the counties around it is how this page reads it.
What these figures count
Only 25 tests were reported to CDC for Broadwater 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).
Broadwater County, Compared
Broadwater County radon figures, compared
Calculated by Radon411CDC's largest figure for Broadwater County rests on 25 tests over the 2008 to 2017 laboratory totals, 14 of them at or above 4 pCi/L, so each test moves its share by 4.0 points and no rank or comparison is drawn from it. Results reached as high as 14.5 pCi/L, with a middle value of 4.1 pCi/L.
Of the counties bordering it, 3 have a figure over the 2006 to 2015 laboratory totals: Jefferson County reported the largest share at or above 4 pCi/L, 66.1%, and Gallatin County the smallest, 48.8%, with Lewis and Clark County at 63.5% between. Farther out, Silver Bow County (63 miles away) at 68.9%, Cascade County (68 miles away) at 35.9% and Madison County (74 miles away) at 47.9% have figures too. Pooled across 52 Montana counties, 47.4% of reported tests reached that level; across every county in the country with a figure, 36.3%.
Statewide for the same period, Sheridan County reported the highest share (75.7%) and Hill County the lowest (35.0%). EPA's 1993 map puts Broadwater 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.
Broadwater County, Geology
The ground under Broadwater County
PredictedUSGS's geologic map puts all of Broadwater County's mapped land in one class: high radon potential. All of it lies in the area the map calls Northern Rocky Mountains, 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 |
|---|---|---|---|---|
| Northern Rocky Mountains | Granitic, metaigneous, metasedimentary rocks, valley fill colluvium and alluvium. | 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.
Broadwater County beside the ground around it
Broadwater County has more high-potential ground than Montana as a whole: 100% of its land against 78.5%. Of the 4 counties that border it, none has as large a share of high-potential ground; Jefferson County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Broadwater County, Local resources
Radon testing and mitigation in Broadwater 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
Broadwater County, Questions
Questions about radon in Broadwater County
Are radon levels high in Broadwater County?
Over the 2008 to 2017 laboratory totals, 56.0% of the radon tests reported to CDC for Broadwater County, Montana were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.1 pCi/L. Of the counties bordering it, 3 have a figure over the 2006 to 2015 laboratory totals: Jefferson County reported the largest share at or above 4 pCi/L, 66.1%, and Gallatin County the smallest, 48.8%, with Lewis and Clark County at 63.5% between.
Which counties border Broadwater County?
Broadwater County borders 4 counties: Jefferson County, Meagher County, Gallatin County and Lewis and Clark County.
Products
Broadwater County, Products
Testing a home in Broadwater County
No CDC figure names Broadwater County; the nearest county with one, Jefferson County (31 miles away), reported 66.1% 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 Broadwater 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
MonitorForensics Detectors
FD-65-RADON rechargeable radon detector with a color screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
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
Broadwater County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Broadwater County
Explore
Broadwater County, Bordering counties
Counties bordering Broadwater County
Calculated by Radon411- Radon levels in Jefferson CountyEPA zone 1
66.1%at or above 4 pCi/L
Median 6.4 pCi/L · 62 tests
- Radon levels in Lewis and Clark CountyEPA zone 1
63.5%at or above 4 pCi/L
Median 5.1 pCi/L · 395 tests
- Radon levels in Gallatin CountyEPA zone 1
48.8%at or above 4 pCi/L
Median 3.8 pCi/L · 914 tests
- Radon levels in Meagher CountyEPA zone 1
0.0%at or above 4 pCi/L
Median 3.6 pCi/L · 1 test
Broadwater County, Cities and towns
Cities and towns in Broadwater County
Broadwater County is growing: the Census Bureau puts it at 8,493 residents on July 1, 2025, up 23.8% from 6,860 in 2020. Spread over its land, that is 7.1 people to the square mile. Townsend, its one incorporated place, has 2,272 residents, 26.8% of the total. Reported testing is thin here: 25 tests over 2008 to 2017, or 2.9 for every 1,000 residents (2025 estimate), where Montana as a whole comes to 8.6.
Townsend is the one incorporated place here; CDC publishes no figure by town, so it reads Broadwater County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Townsend | 2,272 | +24.3% | 26.8% |
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).
Broadwater County, Homes
Homes in Broadwater County
Broadwater County is a place of houses on their own lots: 83% of its 3,164 homes are detached single-family houses, against 69% across Montana. Much of Broadwater County is recent building: 49% of its homes have gone up since 2000 and the middle year built is 1999, against 1980 for Montana. Owners live in 82% of the occupied homes (Montana: 69%), so for most households a test and a fix are their own to order.
| Homes | Broadwater County | Montana |
|---|---|---|
| Housing units | 3,164 | 522,939 |
| Detached houses | 83% | 69% |
| In buildings of 5 or more | 1% | 9% |
| Mobile homes | 13% | 10% |
| Built before 1960 | 14% | 26% |
| Built since 2000 | 49% | 27% |
| Middle year built | 1999 | 1980 |
| Owner-occupied | 82% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.