Sinkhole risk in Waseca County, MN: 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: 99%
At or near the surface: 0%
Buried under cover: 99%

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 417 of Waseca County's 423 square miles on soluble rock. With about 18,684 residents (44 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 400 map points about 1.0 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 99% under cover still counts, and how these percentages are measured.

Counties around Waseca County

The nearest county rated sinkhole country is Clayton County, IA, about 140 miles southeast. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Steele County, MN 18 mi east · 0% at surface
Blue Earth County, MN 24 mi west · 0% at surface
Le Sueur County, MN 25 mi north · 0% at surface
Freeborn County, MN 27 mi southeast · 0% at surface
Rice County, MN 27 mi northeast · 0% at surface
Faribault County, MN 30 mi southwest · 0% at surface

Which formation it is

The largest mapped soluble unit here is the Middle Ordovician rocks, undivided (shale), Middle Ordovician in age, covering about 39% of the county. Next is the Upper and Middle Ordovician rocks, undivided at 38%.

Against the rest of Minnesota

Waseca County ranks 82 of 87 in Minnesota for soluble rock at the surface, and sits above 0% of US counties on that measure.