Sinkhole risk in Olmsted 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: 97%
At or near the surface: 6%
Buried under cover: 91%

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 633 of Olmsted County's 654 square miles on soluble rock, 36 of them with the rock at or near the surface. With about 166,424 residents (255 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 345 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Olmsted County

The nearest county rated sinkhole country is Vernon County, WI, about 84 miles east. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Wabasha County, MN 22 mi northeast · 21% at surface
Dodge County, MN 23 mi west · 0% at surface
Fillmore County, MN 27 mi southeast · 26% at surface
Mower County, MN 29 mi southwest · 0% at surface
Winona County, MN 31 mi east · 27% at surface
Goodhue County, MN 32 mi northwest · 22% at surface

What Olmsted County is built on

The largest mapped soluble unit here is the Upper and Middle Ordovician rocks, undivided (limestone), Late and Middle Ordovician in age, covering about 46% of the county. Next is the Lower Ordovician rocks, undivided at 24%.

Against the rest of Minnesota

Olmsted County ranks 6 of 87 in Minnesota for soluble rock at the surface, and sits above 63% of US counties on that measure.