SinkholeOdds

Sinkhole risk in Walsh 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
10%
At or near the surface
under 1%
Buried under cover
10%

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 124 of Walsh County's 1,282 square miles on soluble rock, 3 of them with the rock at or near the surface. With about 10,214 residents (8 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 402 map points about 1.8 miles apart, so a pocket smaller than that can be missed or overstated.

Read next: why the 10% under cover still counts, and how these percentages are measured.

Counties around Walsh County

The nearest county rated sinkhole country is Boyd County, NE, about 382 miles south. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

The rock underneath

The largest mapped soluble unit here is the Niobrara and Carlile Formations, Undivided (limestone), Cretaceous in age, covering about 8% of the county. Next is the Ordovician rocks at 1%.

Against the rest of North Dakota

Walsh County ranks 6 of 53 in North Dakota for soluble rock at the surface, and sits above 50% of US counties on that measure.