Is Codington County, SD a radon risk area?

EPA's own radon map rates Codington County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally that's the 85th percentile for radon potential — Codington County outranks 85% of every county EPA has rated.

Codington County by the numbers

About 29,278 people live in Codington County, South Dakota, spread over 687.585 square miles. That works out to roughly 43 people per square mile. Rank 474 by population within its EPA zone puts Codington County at the 56th percentile among zone peers. EPA's geology-based Region 8 groups Codington County with 290 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Codington County

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Codington County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Codington County will test well under the action level, and EPA's guidance is to test regardless of zone.

If Codington County tests above the action level

Nothing about Codington County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find South Dakota's state radon program

Codington County's test kit answers today; a Airthings radon monitor keeps answering for Codington County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

More on how this number was built

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.