South Dakota has the third-highest average indoor radon level of any U.S. state, estimated at approximately 7.3 pCi/L statewide. The South Dakota Department of Agriculture and Natural Resources estimates that approximately 60% of South Dakota homes have radon levels above 4.0 pCi/L. South Dakota’s geology — including granitic rock in the Black Hills, glacial till across the east, and uranium-bearing formations — creates some of the highest radon potential in the nation.
EPA Radon Zone Designation
South Dakota is predominantly EPA Radon Zone 1. All South Dakota counties are Zone 1. The Black Hills region in western South Dakota overlies some of the most uranium-rich geology in the U.S., including formations associated with historic uranium mining. Eastern South Dakota counties in the glaciated plains also show consistently high radon levels.
Radon Contractor Licensing in South Dakota
South Dakota requires radon contractors to hold current NRPP or NRSB national certification. The South Dakota Department of Agriculture and Natural Resources administers the state radon program. South Dakota does not have a separate state radon contractor licensing law — national certification is the operative requirement. Verify contractor credentials at nrpp.info or nrsb.org before engaging any radon professional.
Radon Disclosure Requirements in South Dakota
South Dakota’s real estate disclosure requirements under general property disclosure law require sellers to disclose known material defects. South Dakota does not have a radon-specific disclosure statute. However, given that 60% of South Dakota homes exceed the EPA action level, radon is a significant known risk that sellers should address in disclosures when they have knowledge of test results. Real estate agents in South Dakota routinely recommend radon testing during the inspection period.
Radon-Resistant New Construction (RRNC) in South Dakota
South Dakota does not have a statewide RRNC mandate. Given the state’s Zone 1 designation across all counties and one of the nation’s highest average radon levels, EPA and SDANR strongly recommend RRNC for all new South Dakota residential construction. Buyers of new construction — particularly in the Black Hills region and eastern glaciated counties — should request RRNC inclusion in construction contracts.
Highest-Radon Counties and Areas in South Dakota
The Black Hills counties of western South Dakota (Lawrence, Pennington, Custer, Fall River, Meade, Butte) have some of the highest radon potential in the state due to uranium-bearing granitic geology. Eastern South Dakota counties in the glaciated plains — including Minnehaha (Sioux Falls area), Lincoln, Turner, and Lake counties — also show consistently high average readings. The SDANR publishes county-level radon survey data.
Testing Resources for South Dakota Residents
The South Dakota Department of Agriculture and Natural Resources administers the state radon program and provides resources for homeowners including lists of certified contractors, low-cost or free test kit programs (availability varies by year and funding), and technical guidance on radon mitigation. Contact the state radon program directly for the most current contractor list, any available test kit distribution programs, and jurisdiction-specific requirements that may have changed since this page was last updated.
Frequently Asked Questions
How high is radon in South Dakota?
South Dakota has the third-highest average indoor radon level in the U.S. — approximately 7.3 pCi/L. About 60% of South Dakota homes exceed the EPA action level. All 66 counties are Zone 1.
Does South Dakota require radon contractor certification?
NRPP or NRSB national certification is required. No separate state licensing law exists. Verify credentials at nrpp.info or nrsb.org before hiring.
Is the Black Hills area particularly high in radon?
Yes. The Black Hills counties have some of the highest radon potential in South Dakota due to uranium-bearing granitic formations. Lawrence, Pennington, Custer, and Fall River counties are among the highest-radon areas in the state.
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