Sinkhole risk in Douglas 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: 52%
At or near the surface: 0%
Buried under cover: 52%

What to do about a house in Douglas County

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

That works out to roughly 223 of Douglas County's 432 square miles on soluble rock. With about 2,849 residents (7 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 271 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Douglas County

The nearest county rated sinkhole country is Boyd County, NE, about 40 miles southwest. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Charles Mix County, SD 17 mi southwest · 3% at surface
Davison County, SD 22 mi northeast · 0% at surface
Aurora County, SD 26 mi northwest · 0% at surface
Hutchinson County, SD 31 mi east · 0% at surface
Hanson County, SD 35 mi northeast · 0% at surface
Bon Homme County, SD 37 mi southeast · under 1% at surface

The rock underneath

The largest mapped soluble unit here is the Niobrara Formation (limestone), Late Cretaceous in age, covering about 52% of the county.

Against the rest of South Dakota

Douglas County ranks 28 of 66 in South Dakota for soluble rock at the surface, and sits above 0% of US counties on that measure.