Lake County, MT Shrink-Swell Risk
Lake County, MT's soil, for shrink-swell risk
Low
Lake County, MT: USDA's soil survey rates 87% of the county "Low" for shrink-swell potential (1.62% linear extensibility). That's as favorable a county-level reading as this dataset produces - standard foundation practice, pending one lot's own geotechnical report.
What Lake County's reading doesn't cover
Two lots a mile apart in Lake County can carry different soil, even though they share one countywide reading. 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 Lake County.
What it costs to find out, versus to ignore it
With Lake County, MT rating "Low", 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, Lake County, MT is the 2,362-most-constrained of 3,085 rated counties for shrink-swell soil. Within Montana alone it ranks 49 of 54. The county spans 1,491 square miles, home to 33,403 people.
Before you act on this
Orleans Parish, LA carries this site's most-constrained reading. Addison County, VT and Shelby County, OH 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 Montana
Every county in Montana is on this site, including Yellowstone County, MT and Lincoln County, MT. The full underlying dataset is downloadable directly, one row per county.