Is radon high in Stevens County, Washington?

Moderate. The model predicts a long-term basement average of 2.8 pCi/L in Stevens County (about 1.6× the US average of 1.8 and about 1.8× the Washington average of 1.6). That is in the 2-4 pCi/L range where the EPA recommends considering mitigation. Ranked 3 of 39 Washington counties.

Should I test for radon in Stevens County?

Yes, soon. With a predicted average of 2.8 pCi/L, many homes in Stevens County will test above the 4 pCi/L action level. Use a short-term kit first; if it reads 2 or higher, confirm with a long-term test or continuous monitor before deciding on mitigation.

What does EPA Radon Zone 1 mean for Stevens County?

Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and classifies whole counties. The newer model's predicted average of 2.8 pCi/L does not line up with Zone 1, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.

How much does radon mitigation cost in Stevens County?

A standard active sub-slab depressurization system typically runs $800-$2,500 installed nationally; Washington quotes vary with foundation type (slab, crawlspace, basement), home size and local labor. Get two or three bids from certified mitigators listed by your state radon program or the EPA's find-a-professional page.

Radon levels in Stevens County, Washington

ModerateEPA Zone 1

Predicted long-term basement average of 2.8 pCi/L (model estimate) across 16 ZIP codes - about 1.6× the US average of 1.8, about 1.8× the Washington average of 1.6. Ranked #3 of 39 Washington counties.

Test Stevens County, WA - the EPA says "consider fixing" in this range

The predicted basement average here is 2.8 pCi/L, in the 2-4 pCi/L band where the EPA recommends considering mitigation. Plenty of individual homes in a moderate area test above 4. Start with a short-term test; if it comes back at 2 or higher, follow up with a long-term test or a continuous monitor.

Get a short-term test kit →Or track it with a continuous monitor

Already tested at 4 pCi/L or higher? Find a certified mitigation professional (EPA). A mitigation system typically runs $800-$2,500 installed.

We may earn a commission from Amazon at no extra cost to you.

Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.

2.8 ± 0.06

pCi/L predicted basement mean (model SD)

1.9 ± 0.06

pCi/L predicted upstairs (above-ground) mean

2.5-3.1

range of ZIP-level basement predictions in the county

What this means for Stevens

The typical Stevens County home is predicted in the 2-4 pCi/L band. The EPA's guidance for this range is to consider fixing, because there is no known safe level and roughly one home in several in a moderate area will test above 4.

Note that the EPA classifies Stevens County as Zone 1 while the newer model predicts 2.8 pCi/L. The zone map predates two decades of test data; where they disagree, we grade on the model but show both. County figures weight each ZIP by its 2010 Census population, so they describe where people live rather than empty land.

Comparable Washington counties: Ferry County (2.9), Pend Oreille County (3.1), Garfield County (2.4), Columbia County (2.4). The state's highest is Pend Oreille County at 3.1 pCi/L.

ZIP codes in Stevens County

Predicted basement and upstairs means by ZIP (model estimate). ZIPs whose land is mostly in this county.

ZIP	Basement	Upstairs	Grade
99114	2.8 ± 0.06	2.0	Moderate
99109	2.8 ± 0.06	2.0	Moderate
99148	2.9 ± 0.06	1.9	Moderate
99181	2.9 ± 0.06	1.8	Moderate
99013	2.7 ± 0.07	1.6	Moderate
99110	2.8 ± 0.07	1.8	Moderate
99173	2.9 ± 0.07	1.7	Moderate
99101	3.0 ± 0.07	1.8	Moderate
99126	2.6 ± 0.06	1.7	Moderate
99129	2.7 ± 0.06	1.6	Moderate
99040	2.7 ± 0.06	1.6	Moderate
99157	2.8 ± 0.06	1.7	Moderate
99167	3.1 ± 0.07	1.8	Moderate
99137	3.0 ± 0.06	1.9	Moderate
99131	3.1 ± 0.07	1.9	Moderate
99151	2.5 ± 0.06	1.7	Moderate

If your test comes back at 4 pCi/L or higher

Mitigation is a routine job: a fan-driven pipe that vents soil gas from under the slab to above the roofline, typically $800-$2,500 installed (typical range; local quotes vary). Use certified professionals: EPA find-a-professional. Read the full mitigation guide.

Stevens County radon questions

Is radon high in Stevens County, Washington?: Moderate. The model predicts a long-term basement average of 2.8 pCi/L in Stevens County (about 1.6× the US average of 1.8 and about 1.8× the Washington average of 1.6). That is in the 2-4 pCi/L range where the EPA recommends considering mitigation. Ranked 3 of 39 Washington counties.
Should I test for radon in Stevens County?: Yes, soon. With a predicted average of 2.8 pCi/L, many homes in Stevens County will test above the 4 pCi/L action level. Use a short-term kit first; if it reads 2 or higher, confirm with a long-term test or continuous monitor before deciding on mitigation.
What does EPA Radon Zone 1 mean for Stevens County?: Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and classifies whole counties. The newer model's predicted average of 2.8 pCi/L does not line up with Zone 1, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.
How much does radon mitigation cost in Stevens County?: A standard active sub-slab depressurization system typically runs $800-$2,500 installed nationally; Washington quotes vary with foundation type (slab, crawlspace, basement), home size and local labor. Get two or three bids from certified mitigators listed by your state radon program or the EPA's find-a-professional page.

← All Washington counties · How to test · Radon in a home sale · Methodology