Clark County, SD Shrink-Swell Risk

What Clark County, SD's soil means for a foundation

Moderate

USDA's SSURGO data puts Clark County, SD's soil at "Moderate" shrink-swell potential, an area-weighted linear extensibility of 3.59% across 75.3% of the county's surveyed land. A real but modest amount of movement - standard foundations usually hold up, but drainage and moisture control around the foundation still matter more than on low-risk soil.

This is a county figure, not a lot figure

USDA's survey covers the whole of Clark County, SD at once, not any single address. A local geotechnical report, typically $1,000-$5,000 (around $2,700 typical), is the only way to know what one lot in Clark County will actually do.

Report cost vs. repair cost

With Clark County, SD rating "Moderate", a geotechnical report is still worthwhile before a build, just less urgent than in a high-risk county. A geotechnical report runs $1,000-$5,000, typically around $2,700. Foundation repair, if a specific lot turns out to differ from the county average, runs $5,000-$15,000.

Where this sits nationally

Nationally, Clark County, SD is the 789-most-constrained of 3,085 rated counties for shrink-swell soil. Within South Dakota alone it ranks 52 of 66. Clark County covers 958 square miles and counts 3,974 residents.

Before you act on this

Orleans Parish, LA carries this site's most-constrained reading. New Madrid County, MO and Martin County, TX are worth a look for comparison.

How this reading is built, and its real limits · Moisture management: the cheap fix that works on any soil

More of South Dakota

Every county in South Dakota is on this site, including Grant County, SD and Marshall County, SD. The full underlying dataset is downloadable directly, one row per county.