Sinkhole risk in Otero 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: 42%
At or near the surface: 42%
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 526 of Otero County's 1,262 square miles on soluble rock, 526 of them with the rock at or near the surface. With about 17,991 residents (14 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 333 map points about 1.9 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why gypsum and salt move faster than limestone, and the signs to look for and how an inspection works.

Counties around Otero County

The nearest county rated sinkhole country is Clark County, KS, about 219 miles east. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Crowley County, CO 29 mi north · 4% at surface
Bent County, CO 35 mi east · 44% at surface
Las Animas County, CO 43 mi southwest · 29% at surface
Pueblo County, CO 46 mi northwest · 45% at surface
Kiowa County, CO 63 mi northeast · 30% at surface
Huerfano County, CO 69 mi west · 23% at surface

Which formation it is

The largest mapped soluble unit here is the Niobrara Fm (shale), Cretaceous in age, covering about 26% of the county. Next is the Carlile Shale, Greenhorn Limestone, and Graneros Shale at 16%.

The county also lies over the Permian Basin, Anadarko Basin,Dalhart Basin, Palo Duro 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

Otero County ranks 3 of 64 in Colorado for soluble rock at the surface, and sits above 85% of US counties on that measure.