Sinkhole risk in Walworth County, WI: 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%

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 555 of Walworth County's 555 square miles on soluble rock. With about 106,029 residents (191 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 391 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 100% under cover still counts, and how these percentages are measured.

Counties around Walworth County

The nearest county rated sinkhole country is Lafayette County, WI, about 81 miles west. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

McHenry County, IL 24 mi south · 0% at surface
Jefferson County, WI 27 mi northwest · 3% at surface
Waukesha County, WI 27 mi northeast · 0% at surface
Rock County, WI 27 mi west · 0% at surface
Boone County, IL 28 mi southwest · 0% at surface
Kenosha County, WI 34 mi east · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Sinnipee Group (dolostone (dolomite)), Ordovician in age, covering about 51% of the county. Next is the Silurian, undivided at 27%.

Against the rest of Wisconsin

Walworth County ranks 66 of 72 in Wisconsin for soluble rock at the surface, and sits above 0% of US counties on that measure.