Sinkhole risk in Grand County, CO: 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: 6%
At or near the surface: 6%
Buried under cover: 0%

What to do about a house in Grand County

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 109 of Grand County's 1,847 square miles on soluble rock, 109 of them with the rock at or near the surface. With about 16,154 residents (9 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 256 map points about 2.7 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Grand County

The nearest county rated sinkhole country is Dawes County, NE, about 237 miles northeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Summit County, CO 34 mi south · 4% at surface
Gilpin County, CO 35 mi southeast · 0% at surface
Clear Creek County, CO 37 mi southeast · 0% at surface
Boulder County, CO 38 mi east · 4% at surface
Jackson County, CO 40 mi north · 4% at surface
Eagle County, CO 46 mi southwest · 22% at surface

Which formation it is

The largest mapped soluble unit here is the Colorado Group (shale), Cretaceous in age, covering about 6% of the county.

Against the rest of Colorado

Grand County ranks 15 of 64 in Colorado for soluble rock at the surface, and sits above 64% of US counties on that measure.