Is radon high in Grant County, South Dakota?

High. The model predicts a long-term basement average of 4.1 pCi/L in Grant County (about 2.3× the US average of 1.8 and close to the South Dakota average of 3.9). That is at or above the EPA action level of 4 pCi/L, so the typical home here would qualify for mitigation. Ranked 32 of 66 South Dakota counties.

Should I test for radon in Grant County?

Yes, soon. With a predicted average of 4.1 pCi/L and at least one ZIP predicted at 4.3, many homes in Grant County will test above the 4 pCi/L action level. Use a short-term kit first; if it reads 2 or higher, confirm with a long-term test or continuous monitor before deciding on mitigation.

What does EPA Radon Zone 1 mean for Grant County?

Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and classifies whole counties. The 2001-2021 model agrees with the zone here. Neither replaces a test of your own home.

How much does radon mitigation cost in Grant County?

A standard active sub-slab depressurization system typically runs $800-$2,500 installed nationally; South Dakota quotes vary with foundation type (slab, crawlspace, basement), home size and local labor. Get two or three bids from certified mitigators listed by your state radon program or the EPA's find-a-professional page.

Radon levels in Grant County, South Dakota

HighEPA Zone 1

Predicted long-term basement average of 4.1 pCi/L (model estimate) across 10 ZIP codes - about 2.3× the US average of 1.8, close to the South Dakota average of 3.9. Ranked #32 of 66 South Dakota counties.

Test Grant County, SD now - and consider a continuous monitor

The model predicts a long-term basement average of 4.1 pCi/L here, at or above the EPA action level of 4. Homes in the same ZIP still vary widely, so a real test is the only way to know your number. A continuous digital monitor shows how your level swings with weather and season, which matters when you're near the action level.

Get a continuous radon monitor →Or start with a short-term test kit

Already tested at 4 pCi/L or higher? Find a certified mitigation professional (EPA). A mitigation system typically runs $800-$2,500 installed.

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Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.

4.1 ± 0.06

pCi/L predicted basement mean (model SD)

2.4 ± 0.08

pCi/L predicted upstairs (above-ground) mean

3.2-4.3

range of ZIP-level basement predictions in the county

What this means for Grant

The typical home in Grant County is predicted to sit at or above the EPA action level of 4 pCi/L in the basement. In practice that means a large share of houses here would qualify for mitigation if tested, and buyers routinely ask for radon tests in South Dakota transactions.

The 1993 EPA zone (1) and the 2001-2021 model agree for Grant. County figures weight each ZIP by its 2010 Census population, so they describe where people live rather than empty land.

Comparable South Dakota counties: Clark County (4.1), Brown County (4.2), Spink County (4.2), Beadle County (4.1). The state's highest is Jerauld County at 5.2 pCi/L.

ZIP codes in Grant County

Predicted basement and upstairs means by ZIP (model estimate). ZIPs whose land is mostly in this county.

ZIP	Basement	Upstairs	Grade
57252	4.3 ± 0.06	2.4	High
57216	3.8 ± 0.05	2.2	Moderate
57266	3.8 ± 0.06	2.3	Moderate
57259	4.1 ± 0.06	2.3	High
57269	4.0 ± 0.06	2.3	High
57265	3.8 ± 0.06	2.2	Moderate
57264	4.0 ± 0.06	2.3	High
57246	3.8 ± 0.07	2.4	Moderate
57251	3.8 ± 0.06	2.2	Moderate
57256	3.2 ± 0.07	1.9	Moderate

If your test comes back at 4 pCi/L or higher

Mitigation is a routine job: a fan-driven pipe that vents soil gas from under the slab to above the roofline, typically $800-$2,500 installed (typical range; local quotes vary). Use certified professionals: EPA find-a-professional. Read the full mitigation guide.

Grant County radon questions

Is radon high in Grant County, South Dakota?: High. The model predicts a long-term basement average of 4.1 pCi/L in Grant County (about 2.3× the US average of 1.8 and close to the South Dakota average of 3.9). That is at or above the EPA action level of 4 pCi/L, so the typical home here would qualify for mitigation. Ranked 32 of 66 South Dakota counties.
Should I test for radon in Grant County?: Yes, soon. With a predicted average of 4.1 pCi/L and at least one ZIP predicted at 4.3, many homes in Grant County will test above the 4 pCi/L action level. Use a short-term kit first; if it reads 2 or higher, confirm with a long-term test or continuous monitor before deciding on mitigation.
What does EPA Radon Zone 1 mean for Grant County?: Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and classifies whole counties. The 2001-2021 model agrees with the zone here. Neither replaces a test of your own home.
How much does radon mitigation cost in Grant County?: A standard active sub-slab depressurization system typically runs $800-$2,500 installed nationally; South Dakota quotes vary with foundation type (slab, crawlspace, basement), home size and local labor. Get two or three bids from certified mitigators listed by your state radon program or the EPA's find-a-professional page.

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