Gregory County, SD Shrink-Swell Risk
Gregory County, SD's soil, for shrink-swell risk
High
Gregory County, SD: USDA's soil survey rates 38.9% of the county "High" for shrink-swell potential (6.97% linear extensibility). This is enough movement to matter: a standard footing can hold up here, but usually only with real moisture management, not by default.
What Gregory County's reading doesn't cover
Two lots a mile apart in Gregory County can carry different soil, even though they share one countywide reading. A local geotechnical report, typically $1,000-$5,000 (around $2,700 typical), is the only way to know what one lot in Gregory County will actually do.
What it costs to find out, versus to ignore it
Given Gregory County's rating, spending a few thousand now is the way to avoid spending tens of thousands later. The report ($1,000-$5,000) is what tells you whether Gregory County's county-level reading applies to your lot; the repair ($5,000-$15,000) is what it costs if you skip that and find out from the cracks instead.
How Gregory County, SD compares
Nationally, Gregory County, SD is the 78-most-constrained of 3,085 rated counties for shrink-swell soil. Within South Dakota alone it ranks 9 of 66. Gregory County, SD is 1,015 square miles with a population of 4,110.
Before you act on this
Orleans Parish, LA carries this site's most-constrained reading. Ashtabula County, OH and Carbon County, MT are worth a look for comparison.
How this reading is built, and its real limits · The warning signs of expansive-clay damage, explained
More of South Dakota
Every county in South Dakota is on this site, including Moody County, SD and Ziebach County, SD. The full underlying dataset is downloadable directly, one row per county.