Stanley County, SD radon potential

EPA places Stanley County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Nationally, Stanley County ranks higher in radon potential than 69% of rated counties (the 69th percentile).

Where Stanley County sits nationally

Stanley County, South Dakota is home to about 3,015 people across 1,444.436 square miles. That works out to roughly 2 people per square mile. Within its own EPA zone, Stanley County is bigger by population than 8% of the counties that share it. Stanley County falls in EPA Radon Region 8, one of 291 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Stanley County

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Stanley County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. That doesn't mean every Stanley County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

If Stanley County tests above the action level

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

The methodology guide shows exactly which EPA and Census sources feed Stanley County's numbers. Whatever zone Stanley County carries, the zone explainer covers what it does and doesn't tell you about any one house.