Sinkhole risk in Grant County, SD: Mostly deep or small

Mostly deep or small

Some soluble rock, mostly deeply buried or in a small share of the county.

On soluble rock: 2%
At or near the surface: 0%
Buried under cover: 2%

The next step for one property

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 14 of Grant County's 681 square miles on soluble rock. With about 7,618 residents (11 per square mile), much of the land is open, and the mapped rock may sit far from where people actually live. The figures come from 290 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Grant County

The nearest county rated sinkhole country is Knox County, NE, about 184 miles south. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Big Stone County, MN 25 mi northeast · 0% at surface
Codington County, SD 25 mi southwest · 0% at surface
Deuel County, SD 29 mi south · 0% at surface
Lac qui Parle County, MN 31 mi east · 0% at surface
Roberts County, SD 32 mi north · 0% at surface
Hamlin County, SD 39 mi southwest · 0% at surface

What Grant County is built on

The largest mapped soluble unit here is the Niobrara Formation (limestone), Late Cretaceous in age, covering about 2% of the county.

Against the rest of South Dakota

Grant County ranks 31 of 66 in South Dakota for soluble rock at the surface, and sits above 0% of US counties on that measure.