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 Stevens County, Washington
EPA puts Stevens County in Zone 1, its highest radon zone, and 37.8% of its 45 reported radon tests (2020) were at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
37.8%
18.8 pts above WA
- Stevens
- 37.8%
- Washington
- 19.0%
45 tests, 2020
Median result
1.9pCi/L
Below action level
- Stevens
- 1.9 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2020
Tests reported
45
9th of 10 by tests
- Stevens
- 45
- Spokane
- 721
Reported to CDC before any fix, 2020
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Washington
2 of 10
Top quarter
- Stevens
- 37.8%
- Spokane
- 40.6%
By share, of 10 with 30+ tests
Read a result for Stevens County
Starts at Stevens County's median, 1.9 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.9 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Stevens County's median reported result, 2020.
The data
Stevens County, At a glance
Stevens County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Stevens 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 Stevens County, 2020
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 14.8% |
| 2015 | 38.3% |
| 2016 | 42.3% |
| 2017 | 43.6% |
| 2018 | 34.2% |
| 2019 | 49.2% |
| 2020 | 37.8% |
2020: 37.8%. Across these years the share ran from 14.8% to 49.2%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 45 tests reported to CDC for Stevens County over 2020, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.
Measured: CDC tracking data. Figure above: 2020. Measured data period: 2005 to 2020 (every CDC figure on file).
Stevens County, Compared
Stevens County radon figures, compared
Calculated by Radon411In Stevens County, about 4 in 10 reported tests in 2020 (17 of 45) were at or above EPA's action level. Against the national pool of 25.5%, the gap is 12.3 points higher. Across 37 Washington counties pooled together, 19.0% of tests reached that level, so Stevens County runs 18.8 points above its state.
Spokane County, the one bordering county with a figure for the same period, reported 40.6%. By share, Stevens County is 2nd of 10 Washington counties with 30 or more tests for the same period.
Year by year, 2015 opened at 38.3% and 2020 closed at 37.8% (about level), with 2019 the high at 49.2%. Half the tests came in under 1.9 pCi/L and half over it; the single highest reached 35.5 pCi/L. Below the action level, 23 tests (51.1%) came in under 2 pCi/L, against 67.6% statewide, and 5 tests (11.1%) fell between 2 and 4, against 13.3% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 37.8% share point the same way here. USGS geology rates 100% of the county's land high radon potential.
The busiest year on file was 2019, with 63 tests reported; the quietest, 2014, had 27.
Stevens CountyWashington, pooled
37.8% % of tests19.0% % of tests
| Year | Tests | Stevens County, at or above 4 pCi/L | Washington, pooled |
|---|---|---|---|
| 2015 | 47 | 38.3% | 17.4% |
| 2016 | 52 | 42.3% | 16.6% |
| 2017 | 55 | 43.6% | 19.1% |
| 2018 | 38 | 34.2% | 16.1% |
| 2019 | 63 | 49.2% | 20.9% |
| 2020 | 45 | 37.8% | 19.0% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Stevens County, Geology
The ground under Stevens County
PredictedMost of the ground under Stevens County is one class on USGS's geologic map: 99.8% of its land is high radon potential, with 0.2% moderate. All of it lies in the area the map calls Okanogan Highland, to which USGS gives a radon index of 16, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Okanogan Highland | Glaciofluvial outwash and granitic material. Outwash is generally uranium-bearing. | High | 16 | 99.8% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Stevens County beside the ground around it
Stevens County has more high-potential ground than Washington as a whole: 99.8% of its land against 13.7%. Of the 4 counties that border it, 1 has more high-potential ground, Pend Oreille County the most at 99.9%.
The map rates the ground, not the air in any home.
Local help
Stevens County, Local resources
Radon testing and mitigation in Stevens County
- Radon ProgramRadon Program, run by Washington State Department of Health, offers free or discounted test kits, and answers questions about testing and mitigation in Washington.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
We have a limited supply of free radon test kits.
- Compare kits
- See the Washington directoryNo professionals are listed in Washington yet. The state program can point you to registered testers and mitigators.
What Washington's program says
- Phone
- 360-236-3200
- doh.radon@doh.wa.gov
What it means
Stevens County, Questions
Questions about radon in Stevens County
Are radon levels high in Stevens County?
In 2020, 37.8% of the radon tests reported to CDC for Stevens County, Washington were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.9 pCi/L. Of 10 Washington counties with 30 or more tests for the same period, 1 reported a higher share; pooled, the state comes to 19.0%.
Which counties border Stevens County?
Stevens County borders 4 counties: Pend Oreille County, Ferry County, Spokane County and Lincoln County.
Products
Stevens County, Products
Testing a home in Stevens County
In Stevens County, 37.8% of 45 tests reported to CDC in 2020 reached 4 pCi/L, against 19.0% pooled across Washington. In Zone 1 the year-round level in Stevens 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 2 battery digital radon monitor
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- Screen, app
Method: Alpha spectrometry
Readings: Every 60 minutes
Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Stevens County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Stevens County
Explore
Stevens County, Bordering counties
Counties bordering Stevens County
Calculated by Radon411- Radon levels in Lincoln CountyEPA zone 2
45.5%at or above 4 pCi/L
Median 2.4 pCi/L · 11 tests · 7.7 points above Stevens County
- Radon levels in Spokane CountyEPA zone 1
40.6%at or above 4 pCi/L
Median 2.7 pCi/L · 721 tests · 2.8 points above Stevens County
- Radon levels in Pend Oreille CountyEPA zone 1
20.0%at or above 4 pCi/L
Median 2.3 pCi/L · 20 tests · 17.8 points below Stevens County
- Radon levels in Ferry CountyEPA zone 1
20.0%at or above 4 pCi/L
Median 1.6 pCi/L · 10 tests · 17.8 points below Stevens County
Stevens County, Cities and towns
Cities and towns in Stevens County
Stevens County is growing: the Census Bureau puts it at 49,668 residents on July 1, 2025, up 6.6% from 46,585 in 2020. That works out to 20 people per square mile of land. No town dominates: Colville, the largest, has 5,116 residents, 10.3% of the total. Together its 6 incorporated places hold 20.9% of those residents; the other 79.1% live outside any of them. Testing is reported here more often than across the state: CDC's 45 reported tests for 2020 come to 0.9 for every 1,000 residents (2025 estimate), against 0.3 for Washington.
From Colville to Marcus, CDC publishes no figure by town: each reads Stevens County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Colville | 5,116 | +4.1% | 10.3% |
| Chewelah | 2,712 | +9.7% | 5.5% |
| Kettle Falls | 1,657 | +1.3% | 3.3% |
| Springdale | 381 | +60.8% | 0.8% |
| Northport | 294 | +0.3% | 0.6% |
| Marcus | 219 | +2.3% | 0.4% |
6 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).
Stevens County, Homes
Homes in Stevens County
Of Stevens County's 22,577 homes, 74% are detached houses, against 62% across Washington; 20% are mobile homes. Half of its homes were built before 1985, close to Washington's 1984: 18% date from before 1960 and 25% from 2000 or later. Owners live in 79% of the occupied homes (Washington: 64%), so for most households a test and a fix are their own to order.
| Homes | Stevens County | Washington |
|---|---|---|
| Housing units | 22,577 | 3,262,667 |
| Detached houses | 74% | 62% |
| In buildings of 5 or more | 4% | 22% |
| Mobile homes | 20% | 6% |
| Built before 1960 | 18% | 21% |
| Built since 2000 | 25% | 28% |
| Middle year built | 1985 | 1984 |
| Owner-occupied | 79% | 64% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.