Sinkhole risk in Lake 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: 29%
At or near the surface: 0%
Buried under cover: 29%

What to do about a house in Lake County

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

That works out to roughly 160 of Lake County's 563 square miles on soluble rock. With about 11,006 residents (20 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 407 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 29% under cover still counts, and how these percentages are measured.

Counties around Lake County

The nearest county rated sinkhole country is Knox County, NE, about 104 miles south. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Moody County, SD 22 mi east · 0% at surface
Miner County, SD 24 mi west · 0% at surface
McCook County, SD 27 mi southwest · 0% at surface
Brookings County, SD 29 mi northeast · 0% at surface
Kingsbury County, SD 30 mi northwest · 0% at surface
Minnehaha County, SD 30 mi southeast · 0% at surface

What Lake County is built on

The largest mapped soluble unit here is the Niobrara Formation (limestone), Late Cretaceous in age, covering about 29% of the county.

Against the rest of South Dakota

Lake County ranks 44 of 66 in South Dakota for soluble rock at the surface, and sits above 0% of US counties on that measure.