Sinkhole risk in Sarpy County, NE: 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: 45%
At or near the surface: 0%
Buried under cover: 45%

What to do about a house in Sarpy County

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

That works out to roughly 108 of Sarpy County's 238 square miles on soluble rock. With about 204,828 residents (861 per square mile), most of the county is built up, so a mapped unit is likely to sit under somebody's street. The figures come from 304 map points about 0.9 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 45% under cover still counts, and how these percentages are measured.

Counties around Sarpy County

The nearest county rated sinkhole country is Knox County, NE, about 139 miles northwest. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Douglas County, NE 13 mi north · 0% at surface
Cass County, NE 14 mi south · 0% at surface
Mills County, IA 26 mi east · 0% at surface
Saunders County, NE 29 mi west · 0% at surface
Washington County, NE 30 mi north · 0% at surface
Otoe County, NE 33 mi south · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Kansas City Group (limestone), Late Pennsylvanian- Missouria in age, covering about 39% of the county. Next is the Lansing Group at 5%.

Against the rest of Nebraska

Sarpy County ranks 81 of 93 in Nebraska for soluble rock at the surface, and sits above 0% of US counties on that measure.