Locations and reports
Radon Levels in Stillwater County, Montana
What this means for you
- Your area: EPA rates Stillwater County Zone 1, the highest of its three radon zones. That is a prediction for the whole county, and homes with elevated levels occur in all three zones.
- Local tests: Of 59 radon tests reported to CDC for Stillwater County (2008 to 2017), 55.9% were at or above 4 pCi/L, EPA's action level.
- Your home: The only way to know your home’s level is to test it.
pCi/L (picocuries per liter) is the unit radon is measured in. EPA recommends fixing a home at 4 pCi/L or above, its action level.
Over the 2008 to 2017 laboratory totals, 55.9% of the radon tests reported to CDC for Stillwater County, Montana came back at or above the EPA action level of 4 pCi/L, and the median result was 4.8 pCi/L. EPA's Map of Radon Zones places the county in Zone 1, highest predicted potential. Radon levels vary from home to home, so only a test measures the level in yours.
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county as a whole.
This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.
USGS geologic potential: Moderate across 100% of the county's land area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Stillwater County, 2008 to 2017, laboratory
- Tests reported
- 59
- At or above 4 pCi/L
- 55.9%
- Median result
- 4.8 pCi/L
Of 59 pre-mitigation tests reported to CDC, not homes in this area. CDC publishes the share in each band, not a count per band, so the per-band counts in the table are calculated by Radon411 and rounded to add up to the published total.
| Result band | Tests Calculated by Radon411 | Share Measured |
|---|---|---|
| Under 2 pCi/L | 17 | 28.8% |
| 2 to 4 pCi/L | 9 | 15.3% |
| 4 pCi/L and above | 33 | 55.9% |
Distribution of tested buildings, not this house. People testing before a sale, or because they suspect a problem, are over-represented in any reported testing data.
Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Stillwater County, In figures
Stillwater County in figures
What the published data says about Stillwater County, in words. A zone and a share of tests describe an area, never the level in any one home.
Predicted
PredictedEPA places Stillwater County in Zone 1, highest predicted potential, as it does 48 other counties of Montana's 56.
Of the 5 bordering counties, EPA places Carbon County and Park County in Zone 1 and Golden Valley County, Sweet Grass County and Yellowstone County in Zone 2.
Reported tests
MeasuredCDC publishes no annual figure for Stillwater County; its figure is a laboratory total for 2008 to 2017: 55.9% of 59 reported tests were at or above 4 pCi/L.
Local record
Montana's radon program is the Radon Control Program, run by Montana DEQ; its contacts are under Local resources.
The county's largest incorporated place is Columbus; the figures here cover them as part of the county.
Stillwater County, Comparison
How Stillwater County compares
MeasuredStillwater County's own published CDC figures beside those of the counties that border it, for the same period.
Share of reported tests at or above 4 pCi/L
Measured2008 to 2017, laboratory, highest first. Each county’s own published CDC figure.
- Sweet Grass CountyMT9 tests88.9%
- Park CountyMT150 tests60.0%
- Stillwater CountyThis page59 tests55.9%
- Carbon CountyMT46 tests52.2%
- Yellowstone CountyMT1,520 tests42.4%
Median reported result
Measured2008 to 2017, laboratory, highest first. Each county’s own published CDC figure.
- Sweet Grass CountyMT9 tests11.9 pCi/L
- Park CountyMT150 tests5.3 pCi/L
- Stillwater CountyThis page59 tests4.8 pCi/L
- Carbon CountyMT46 tests4.2 pCi/L
- Yellowstone CountyMT1,520 tests3.4 pCi/L
Each figure is that county’s own published CDC figure for 2008 to 2017, laboratory, counting radon tests reported to CDC, not homes. Stillwater County is this page. Nothing is averaged or combined across counties. The test count beside each county is CDC’s published number of pre-mitigation tests behind its figures. Figures from few tests can swing widely from year to year. No published CDC figure for 2008 to 2017, laboratory: Golden Valley County, MT. Every Montana county’s own figure is in the Montana county table.
CDC publishes this figure only for counties here, so there is no state or national number to compare Stillwater County, Montana with.
Stillwater County, Bordering counties
Counties bordering Stillwater County
Calculated by Radon4115 counties share a boundary with Stillwater County, computed from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county’s report can be worth reading alongside this one.
Stillwater County, Local resources
Local resources in Montana
Who to ask in Montana: the state's radon program, test kits and professionals.
Radon Control Program
Montana DEQ
Montana’s radon program answers questions about testing, mitigation and the rules where you live.
- Phone
- 1-800-546-0483
- Licensing of radon professionals
Montana DEQ does not certify or require proof of certification for the contractors listed.
Test kits
The program says: Energy Bureau staff manage the radon information toll-free hotline and distribute subsidized radon test kits to Montana residents.
Radon professionals
No professionals are listed in Montana yet. The state program can point you to registered testers and mitigators.
See the Montana directoryStillwater County, Cities and towns
Cities and towns in Stillwater County
The radon figures on this page are for Stillwater County as a whole. They do not differ by city or town.
- Columbus
One incorporated place, as listed in the U.S. Census Bureau’s 2020 place reference files.
Stillwater County, Questions
Questions about radon in Stillwater County
Common questions8 questions, answered from the figures above
Are radon levels high in Stillwater County?
In 2017, 55.9% of the radon tests reported to CDC for Stillwater County, Montana were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.8 pCi/L. That is a share of reported tests, not of homes. EPA places Stillwater County in Zone 1, highest predicted potential, a predicted average indoor screening level greater than 4 pCi/L. Homes with elevated levels occur in all three zones, so the figures describe the area, not your house. Testing is the only way to know the radon level in a specific building.
How do I get a radon test in Stillwater County?
EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. No certified tester listed on Radon411 names Stillwater County as a service area yet. The Montana radon program is the place to ask about certified testers and any test kit offer it runs.
How to test a homeTest kits comparedFree and low-cost kits by stateMontana radon program
Who does radon mitigation in Stillwater County?
Radon411 has no certified mitigators listed for Montana yet. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional. Your state radon program is the place to check whether Montana requires one.
How radon mitigation worksWhat mitigation costsMontana radon program
What EPA radon zone is Stillwater County in?
EPA places Stillwater County, Montana in Zone 1, which EPA describes as highest predicted potential for the area. A zone is a prediction for the whole county and never determines whether a particular home should be tested. EPA recommends testing every home regardless of zone.
Should I test my home in Stillwater County?
Yes. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. How to test a home.
When is the best time of year to test?
EPA says short-term tests stay in the home from 2 to 90 days and that all radon tests should run a minimum of 48 hours; long-term tests stay more than 90 days. EPA's guides do not name a best season: they say radon levels tend to vary from day to day and season to season, so a long-term test is more likely than a short-term test to tell you the year-round average.
What does it cost to test?
EPA's Citizen's Guide calls testing easy and inexpensive, and EPA's Home Buyer's and Seller's Guide says passive short-term and long-term devices are generally inexpensive, while active devices may cost more. No national average price is published for this, so Radon411 does not give one. What testing costs.
Which counties border Stillwater County?
Stillwater County borders 5 counties, derived from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county's report can be relevant.
What these figures mean if you own, buy, sell or rent
The reported-test figures on this page describe Stillwater County, Montana in 2017. They describe tests other people carried out in other buildings, and none of them measures yours.
- How to test a home
If you own your home
Test the lowest lived-in level; a short-term kit screens in days, a long-term kit reflects the year.
- Buying a house: radon guide
If you are buying
Ask for past results and any system's post-mitigation test, and test during the sale.
- Selling a house: radon guide
If you are selling
Testing before you list puts the timing in your hands; disclosure rules differ by state.
- Radon in rental homes
If you rent, or rent out a home
A tenant can test; a fix is the owner's to make, and duties differ by state.
How long a test has to run, under what conditions, and what EPA says a result means: the testing standard, in full.
Stillwater County, Products
Testing and mitigation products
Whatever the figures for Stillwater County show, only a test tells you about one home.
Testing
- Short-term test kitsPassive detectors exposed for a few days under closed-building conditions, then analyzed by a lab.
- Long-term test kitsDetectors exposed for more than 90 days, for a closer picture of the annual average.
- Continuous monitorsPowered devices that log radon on a repeating cycle, often used for transaction tests.
- Digital detectorsConsumer devices that display a running radon reading without a lab.
- Water radon testsKits for radon dissolved in well water, analyzed by a lab.
Mitigation
- Mitigation fansThe inline fan that keeps a soil depressurization system running, sized by the installer.
- System indicatorsU-tube manometers and fan alarms that show whether a mitigation system is still working.
- Sealing materialsCrack, joint and sump sealing used alongside a mitigation system, not instead of one.
Stillwater County / Next steps
What to do next
Learn
Know what radon is
What radon is, how it gets indoors, and why a county zone is not a reading for your home.
Learn about radonTest
Test the building you live in
Short-term or long-term, where the device goes, and closed-house conditions.
How to testFix
Bring a high level down
How a mitigation system works, and the retest that confirms it.
How mitigation worksFind a pro
Hire a certified professional
Measurement and mitigation professionals by state, with their certifications.
Find a professional
Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.