Pondera County, MT Shrink-Swell Risk
What Pondera County, MT's soil means for a foundation
Moderate
USDA's SSURGO data puts Pondera County, MT's soil at "Moderate" shrink-swell potential, an area-weighted linear extensibility of 4.01% across 55.2% of the county's surveyed land. That's a middle reading: not the sharp swings that crack a foundation outright, but enough that grading and drainage are worth getting right.
This is a county figure, not a lot figure
USDA's survey covers the whole of Pondera County, MT at once, not any single address. The real answer for one lot is still a site-specific geotechnical report, running about $1,000-$5,000 (typically near $2,700).
Report cost vs. repair cost
With Pondera County, MT 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.
How Pondera County, MT compares
Nationally, Pondera County, MT is the 562-most-constrained of 3,085 rated counties for shrink-swell soil. Within Montana alone it ranks 15 of 54. Pondera County, MT is 1,625 square miles with a population of 6,078.
See how another county compares
Orleans Parish, LA carries this site's most-constrained reading. Cumberland County, KY and Carter County, MT 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 Mineral County, MT. The full underlying dataset is downloadable directly, one row per county.