Sinkhole risk in Keya Paha County, NE: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 21%
At or near the surface: 21%
Buried under cover: 0%

What to do about a house in Keya Paha County

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 160 of Keya Paha County's 773 square miles on soluble rock, 160 of them with the rock at or near the surface. With about 819 residents (1 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 338 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why gypsum and salt move faster than limestone, and the signs to look for and how an inspection works.

Counties around Keya Paha County

The nearest county rated sinkhole country is Boyd County, NE, about 48 miles east. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Gregory County, SD 33 mi northeast · 17% at surface
Tripp County, SD 34 mi north · 3% at surface
Rock County, NE 36 mi southeast · 5% at surface
Brown County, NE 37 mi south · under 1% at surface
Boyd County, NE 48 mi east · 69% at surface
Todd County, SD 55 mi northwest · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Pierre Shale (shale), Late Cretaceous in age, covering about 21% of the county.

21% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

Against the rest of Nebraska

Keya Paha County ranks 16 of 93 in Nebraska for soluble rock at the surface, and sits above 75% of US counties on that measure.