Dewey County, SD radon potential

Dewey County is mapped as Zone 2 - Moderate Potential by EPA — meaning the county-wide average indoor level is predicted between 2 and 4 pCi/L. Rank it against the rest of the country and Dewey County lands in the 36th percentile for radon potential.

Where Dewey County sits nationally

Dewey County, South Dakota is home to about 5,322 people across 2,302.376 square miles. Averaged across its land area, Dewey County runs about 2 people per square mile. Within its own EPA zone, Dewey County is bigger by population than 9% of the counties that share it. EPA's geology-based Region 8 groups Dewey County with 290 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Dewey County

EPA's Zone 2 rating for Dewey County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. Middle-of-the-pack doesn't mean risk-free for any one Dewey County address — a moderate county average still leaves individual homes to test either side of it.

Next steps for a home in Dewey County

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find South Dakota's state radon program

For Dewey County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Dewey 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 Dewey County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Dewey County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.