Winneshiek County, IA: EPA's radon zone, explained

Winneshiek County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. That puts Winneshiek County in the 82nd percentile nationally for radon potential — higher than 82% of the counties EPA has rated.

How Winneshiek County compares

Winneshiek County, Iowa is home to about 19,723 people across 689.844 square miles. Averaged across its land area, Winneshiek County runs about 29 people per square mile. By population, Winneshiek County is the 579th largest of every county sharing its EPA zone — the 46th percentile by population within that zone. Winneshiek County falls in EPA Radon Region 7, one of 412 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Winneshiek County

Winneshiek County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. Being in Zone 1 raises the odds Winneshiek County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

Next steps for a home in Winneshiek County

For a Winneshiek 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 Iowa's state radon program

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

Where Winneshiek County's figures come from

Winneshiek County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.