Sinkhole risk in Harrison 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: 81%
At or near the surface: 0%
Buried under cover: 81%

The next step for one property

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

That works out to roughly 562 of Harrison County's 697 square miles on soluble rock. With about 14,626 residents (21 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 347 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 81% under cover still counts, and how these percentages are measured.

Counties around Harrison County

The nearest county rated sinkhole country is Knox County, NE, about 124 miles northwest. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Washington County, NE 23 mi southwest · 0% at surface
Monona County, IA 26 mi north · 0% at surface
Shelby County, IA 27 mi east · 0% at surface
Pottawattamie County, IA 28 mi southeast · 0% at surface
Burt County, NE 29 mi northwest · 0% at surface
Douglas County, NE 32 mi southwest · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Kansas City Group (limestone), Late Pennsylvanian-Missouri Series in age, covering about 80% of the county. Next is the Kansas City Group at under 1%.

Against the rest of Iowa

Harrison County ranks 49 of 99 in Iowa for soluble rock at the surface, and sits above 0% of US counties on that measure.