Sinkhole risk in Anoka 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: 7%
At or near the surface: 0%
Buried under cover: 7%

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 30 of Anoka County's 422 square miles on soluble rock. With about 376,840 residents (893 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 284 map points about 1.2 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 7% under cover still counts, and how these percentages are measured.

Counties around Anoka County

The nearest county rated sinkhole country is Vernon County, WI, about 166 miles southeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Ramsey County, MN 19 mi south · 0% at surface
Isanti County, MN 20 mi north · 0% at surface
Hennepin County, MN 22 mi southwest · 0% at surface
Chisago County, MN 23 mi northeast · 0% at surface
Washington County, MN 24 mi southeast · 0% at surface
Sherburne County, MN 28 mi northwest · 0% at surface

What Anoka County is built on

The largest mapped soluble unit here is the Lower Ordovician rocks, undivided (dolostone (dolomite)), Lower Ordovician in age, covering about 5% of the county. Next is the Middle Ordovician rocks, undivided at 3%.

Against the rest of Minnesota

Anoka County ranks 9 of 87 in Minnesota for soluble rock at the surface, and sits above 0% of US counties on that measure.