Sinkhole risk in Pierce County, WI: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 82%
At or near the surface: 35%
Buried under cover: 47%

What this means before you buy

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 471 of Pierce County's 574 square miles on soluble rock, 200 of them with the rock at or near the surface. With about 43,380 residents (76 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 330 map points about 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Pierce County

The nearest county rated sinkhole country is Vernon County, WI, about 111 miles southeast. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

St. Croix County, WI 21 mi north · 1% at surface
Goodhue County, MN 26 mi southwest · 22% at surface
Pepin County, WI 30 mi east · 23% at surface
Dunn County, WI 30 mi northeast · 2% at surface
Washington County, MN 31 mi northwest · 0% at surface
Dakota County, MN 31 mi west · 0% at surface

Which formation it is

The largest mapped soluble unit here is the Prairie du Chien Group (shale), Lower Ordovician in age, covering about 55% of the county. Next is the Ancell Group at 23%.

Against the rest of Wisconsin

Pierce County ranks 8 of 72 in Wisconsin for soluble rock at the surface, and sits above 81% of US counties on that measure.