What EPA's radon map says about Ouray County

EPA places Ouray 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. Ouray County sits at the 71st percentile nationally for radon potential — above 71 of every 100 rated counties.

Where Ouray County sits nationally

About 5,197 people live in Ouray County, Colorado, spread over 540.671 square miles. That works out to roughly 10 people per square mile. Among counties sharing Ouray County's EPA zone, it outranks 14% of them by population. EPA's geology-based Region 8 groups Ouray County with 290 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Ouray 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 Ouray County will test well under the action level, and EPA's guidance is to test regardless of zone.

Testing and mitigation in Ouray County

Mitigation cost doesn't depend on Ouray 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 Colorado's state radon program

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

More on how this number was built

Ouray 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.