Walsh County, ND Radon Zone Data

Walsh County, ND radon potential

Walsh County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Walsh County sits at the 76th percentile nationally for radon potential — above 76 of every 100 rated counties.

Walsh County by the numbers

Walsh County, North Dakota is home to about 10,214 people across 1,281.607 square miles. Averaged across its land area, Walsh County runs about 8 people per square mile. Within its own EPA zone, Walsh County is bigger by population than 29% of the counties that share it. Geologically, Walsh County is grouped into EPA Region 8 alongside 290 other counties that share its rock and soil setting.

Zone vs. an actual test

Walsh 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. 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 Walsh County will test well under the action level, and EPA's guidance is to test regardless of zone.

If Walsh 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 North Dakota's state radon program

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

Where Walsh County's figures come from

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