SinkholeOdds

Sinkhole risk in Turner 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
39%
At or near the surface
0%
Buried under cover
39%

What this means before you buy

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

That works out to roughly 243 of Turner County's 617 square miles on soluble rock. With about 9,087 residents (15 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 355 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 39% under cover still counts, and how these percentages are measured.

Counties around Turner County

The nearest county rated sinkhole country is Knox County, NE, about 60 miles southwest. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

The rock underneath

The largest mapped soluble unit here is the Niobrara Formation (limestone), Late Cretaceous in age, covering about 39% of the county.

Against the rest of South Dakota

Turner County ranks 62 of 66 in South Dakota for soluble rock at the surface, and sits above 0% of US counties on that measure.