Mellette County, SD Shrink-Swell Risk
Mellette County's SSURGO shrink-swell reading
High
In Mellette County, SD, 30.7% of the surveyed soil carries a "High" shrink-swell rating, 7.27% linear extensibility on average. Ground like this needs active moisture control to keep a conventional foundation from cracking - it's not automatic either way.
Before you rely on this for one address
Mellette County's reading is an average across the whole county, not a promise about any one lot inside it. A site-specific soil report, usually $1,000-$5,000, is what an engineer would actually pull before designing a foundation on a lot in Mellette County.
Budgeting for Mellette County, SD
Mellette County's soil reading is exactly the case where a report before construction, or before cracks widen, pays for itself. A geotechnical report runs $1,000-$5,000 (typically $2,700); an actual foundation repair, once cracking sets in, typically runs $5,000-$15,000 (around $10,000 typical) - roughly 4x the report.
Where this sits nationally
Among the 3,085 rated counties on this site, Mellette County, SD ranks 71 most-constrained nationally, and 7 of 66 within South Dakota. Mellette County covers 1,307 square miles and counts 1,834 residents.
See how another county compares
Orleans Parish, LA carries this site's most-constrained reading. Adams County, NE and Kittitas County, WA are worth a look for comparison.
How this reading is built, and its real limits · The warning signs of expansive-clay damage, explained
Elsewhere in South Dakota
Every county in South Dakota is on this site, including Day County, SD and Yankton County, SD. The full underlying dataset is downloadable directly, one row per county.