SinkholeOdds

Sinkhole risk in Buffalo 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
3%
Buried under cover
4%

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 30 of Buffalo County's 471 square miles on soluble rock, 14 of them with the rock at or near the surface. With about 1,825 residents (4 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 342 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Buffalo County

The nearest county rated sinkhole country is Boyd County, NE, about 82 miles south. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Which formation it is

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

Buffalo County ranks 11 of 66 in South Dakota for soluble rock at the surface, and sits above 60% of US counties on that measure.