Sinkhole risk in Winona County, MN: Pockets of it

Pockets of it

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

On soluble rock: 69%
At or near the surface: 27%
Buried under cover: 42%

What to do about a house in Winona County

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 433 of Winona County's 626 square miles on soluble rock, 170 of them with the rock at or near the surface. With about 49,973 residents (80 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 269 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 42% under cover still counts, and the signs to look for and how an inspection works.

Counties around Winona County

The nearest county rated sinkhole country is Vernon County, WI, about 54 miles southeast. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Houston County, MN 26 mi southeast · 28% at surface
Fillmore County, MN 26 mi southwest · 26% at surface
Buffalo County, WI 28 mi north · 31% at surface
Trempealeau County, WI 30 mi northeast · 5% at surface
Wabasha County, MN 31 mi northwest · 21% at surface
Olmsted County, MN 31 mi west · 6% at surface

What Winona County is built on

The largest mapped soluble unit here is the Lower Ordovician rocks, undivided (dolostone (dolomite)), Lower Ordovician in age, covering about 64% of the county. Next is the Middle Ordovician rocks, undivided at 3%.

Against the rest of Minnesota

Winona County ranks 2 of 87 in Minnesota for soluble rock at the surface, and sits above 78% of US counties on that measure.