What EPA's radon map says about Golden Valley County

EPA places Golden Valley County in Zone 2 - Moderate Potential — a predicted county-wide average indoor radon level between 2 and 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Golden Valley County sits at the 33rd percentile nationally for radon potential — above 33 of every 100 rated counties.

Where Golden Valley County sits nationally

About 863 people live in Golden Valley County, Montana, spread over 1,174.423 square miles. Population density there runs about 1 people per square mile. Among counties sharing Golden Valley County's EPA zone, it outranks 1% of them by population. EPA's geology-based Region 8 groups Golden Valley County with 290 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Call it a middle case: above the 1.3 pCi/L most US homes average, below the 4 pCi/L line EPA uses to recommend mitigation — that's Golden Valley County's Zone 2 prediction. A county-wide moderate average, like Golden Valley County's, can still hide a specific house well above or below it — testing is what actually answers the question.

If Golden Valley County tests above the action level

Mitigation cost doesn't depend on Golden Valley County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Montana's state radon program

Golden Valley County's test kit answers today; a Airthings radon monitor keeps answering for Golden Valley 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

The methodology guide shows exactly which EPA and Census sources feed Golden Valley County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.