Sinkhole risk in Hennepin 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: 51%
At or near the surface: 0%
Buried under cover: 51%

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 284 of Hennepin County's 554 square miles on soluble rock. With about 1,273,334 residents (2,298 per square mile), most of the county is built up, so a mapped unit is likely to sit under somebody's street. The figures come from 265 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why the 51% under cover still counts, and how these percentages are measured.

Counties around Hennepin County

The nearest county rated sinkhole country is Vernon County, WI, about 163 miles southeast. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Ramsey County, MN 18 mi east · 0% at surface
Carver County, MN 20 mi southwest · 0% at surface
Anoka County, MN 22 mi northeast · 0% at surface
Scott County, MN 25 mi south · 0% at surface
Wright County, MN 27 mi northwest · 0% at surface
Washington County, MN 29 mi east · 0% at surface

What Hennepin County is built on

The largest mapped soluble unit here is the Middle Ordovician rocks, undivided (shale), Middle Ordovician in age, covering about 37% of the county. Next is the Lower Ordovician rocks, undivided at 14%.

Against the rest of Minnesota

Hennepin County ranks 32 of 87 in Minnesota for soluble rock at the surface, and sits above 0% of US counties on that measure.