Sinkhole risk in Brookings 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: 18%
At or near the surface: 0%
Buried under cover: 18%

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 146 of Brookings County's 792 square miles on soluble rock. With about 36,359 residents (46 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 392 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 18% under cover still counts, and how these percentages are measured.

Counties around Brookings County

The nearest county rated sinkhole country is Knox County, NE, about 132 miles southwest. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Moody County, SD 26 mi south · 0% at surface
Lincoln County, MN 26 mi east · 0% at surface
Deuel County, SD 27 mi north · 0% at surface
Hamlin County, SD 28 mi northwest · 0% at surface
Lake County, SD 29 mi southwest · 0% at surface
Kingsbury County, SD 35 mi west · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Niobrara Formation (limestone), Late Cretaceous in age, covering about 18% of the county.

Against the rest of South Dakota

Brookings County ranks 17 of 66 in South Dakota for soluble rock at the surface, and sits above 0% of US counties on that measure.