Chelan County, WA: EPA's radon zone, explained

Chelan County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Rank it against the rest of the country and Chelan County lands in the 25th percentile for radon potential.

Chelan County by the numbers

Chelan County, Washington is home to about 81,228 people across 2,921.178 square miles. That works out to roughly 28 people per square mile. By population, Chelan County is the 249th largest of every county sharing its EPA zone — the 76th percentile by population within that zone. Geologically, Chelan County is grouped into EPA Region 10 alongside 141 other counties that share its rock and soil setting.

Zone vs. an actual test

Chelan County's Zone 3 prediction undercuts the roughly 1.3 pCi/L most US homes average, nowhere near EPA's 4 pCi/L threshold for recommending mitigation. Don't read Zone 3 as a pass for Chelan County — EPA's guidance to test every home makes no exception for counties predicted low.

Testing and mitigation in Chelan County

For a Chelan County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Washington's state radon program

For Chelan County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Chelan County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

Where Chelan County's figures come from

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Chelan County carries, the zone explainer covers what it does and doesn't tell you about any one house.