Sinkhole risk in Bremer 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: 100%
At or near the surface: 0%
Buried under cover: 100%

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 435 of Bremer County's 435 square miles on soluble rock. With about 25,328 residents (58 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 405 map points about 1.0 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 100% under cover still counts, and how these percentages are measured.

Counties around Bremer County

The nearest county rated sinkhole country is Clayton County, IA, about 51 miles east. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Chickasaw County, IA 19 mi north · 0% at surface
Black Hawk County, IA 21 mi south · 0% at surface
Butler County, IA 23 mi west · 0% at surface
Fayette County, IA 25 mi east · 19% at surface
Floyd County, IA 30 mi northwest · 0% at surface
Buchanan County, IA 33 mi southeast · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Cedar Valley Limestone (limestone), Middle Dovonian in age, covering about 38% of the county. Next is the Niagaran Series at 26%.

Against the rest of Iowa

Bremer County ranks 21 of 99 in Iowa for soluble rock at the surface, and sits above 0% of US counties on that measure.