Sinkhole risk in Roberts 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: 6%
At or near the surface: 0%
Buried under cover: 6%

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 61 of Roberts County's 1,101 square miles on soluble rock. With about 10,283 residents (9 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 273 map points about 2.0 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 6% under cover still counts, and how these percentages are measured.

Counties around Roberts County

The nearest county rated sinkhole country is Boyd County, NE, about 209 miles southwest. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Traverse County, MN 25 mi northeast · 0% at surface
Big Stone County, MN 30 mi southeast · 0% at surface
Marshall County, SD 32 mi west · 0% at surface
Grant County, SD 32 mi south · 0% at surface
Day County, SD 36 mi southwest · 0% at surface
Richland County, ND 44 mi north · 0% at surface

What Roberts County is built on

The largest mapped soluble unit here is the Niobrara Formation (limestone), Late Cretaceous in age, covering about 6% of the county.

Against the rest of South Dakota

Roberts County ranks 56 of 66 in South Dakota for soluble rock at the surface, and sits above 0% of US counties on that measure.