SinkholeOdds

Sinkhole risk in Grand Forks County, ND: 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
16%
At or near the surface
0%
Buried under cover
16%

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 223 of Grand Forks County's 1,436 square miles on soluble rock. With about 73,771 residents (51 per square mile), much of the land is open, and the mapped rock may sit far from where people actually live. The figures come from 328 map points about 2.1 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why the 16% under cover still counts, and how these percentages are measured.

Counties around Grand Forks County

The nearest county rated sinkhole country is Boyd County, NE, about 354 miles south. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

What Grand Forks County is built on

The largest mapped soluble unit here is the Ordovician rocks (limestone), Ordovician in age, covering about 9% of the county. Next is the Niobrara and Carlile Formations, Undivided at 7%.

Against the rest of North Dakota

Grand Forks County ranks 21 of 53 in North Dakota for soluble rock at the surface, and sits above 0% of US counties on that measure.