Sinkhole risk in Eagle County, CO: Pockets of it

Pockets of it

Soluble rock at the surface or under thin cover in part of the county.

On soluble rock: 22%
At or near the surface: 22%
Buried under cover: 0%

What this means before you buy

Check the parcel against your state survey sinkhole map, and ask for an inspection if cracks, depressions or sticking doors show up.

That works out to roughly 366 of Eagle County's 1,684 square miles on soluble rock, 366 of them with the rock at or near the surface. With about 54,330 residents (32 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 359 map points about 2.2 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Eagle County

The nearest county rated sinkhole country is Emery County, UT, about 219 miles west. None of the 6 closest counties land in the same band, so Eagle County stands out from its surroundings.

Summit County, CO 30 mi east · 4% at surface
Pitkin County, CO 31 mi southwest · 5% at surface
Lake County, CO 34 mi southeast · 5% at surface
Grand County, CO 46 mi northeast · 6% at surface
Clear Creek County, CO 55 mi east · 0% at surface
Routt County, CO 61 mi north · under 1% at surface

Which formation it is

The largest mapped soluble unit here is the Eagle Valley Fm - evaporitic facies (siltstone), Pennsylvanian in age, covering about 11% of the county. Next is the Colorado Group at 3%.

15% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

The county also lies over the Eagle Valley Basin, a deep salt or gypsum basin. Deep beds rarely cause surface collapse on their own, but wells and mining into them have.

Against the rest of Colorado

Eagle County ranks 8 of 64 in Colorado for soluble rock at the surface, and sits above 75% of US counties on that measure.