SinkholeOdds

Sinkhole risk in Wapello County, IA: 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
17%
At or near the surface
0%
Buried under cover
17%

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 75 of Wapello County's 432 square miles on soluble rock. With about 35,681 residents (83 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 390 map points about 1.1 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 why the 17% under cover still counts.

Counties around Wapello County

The nearest county rated sinkhole country is Clayton County, IA, about 137 miles northeast. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Which formation it is

The largest mapped soluble unit here is the Meramec Series (limestone), Late Mississippian in age, covering about 17% of the county.

The county also lies over the Forest City Basin, a deep salt or gypsum basin. Deep beds rarely cause surface collapse on their own, but wells and mining into them have.

Against the rest of Iowa

Wapello County ranks 91 of 99 in Iowa for soluble rock at the surface, and sits above 0% of US counties on that measure.