Sinkhole risk in Rio Blanco 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: 1%
At or near the surface: 1%
Buried under cover: 0%

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 42 of Rio Blanco County's 3,221 square miles on soluble rock, 42 of them with the rock at or near the surface. With about 6,607 residents (2 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 318 map points about 3.2 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 how these percentages are measured.

Counties around Rio Blanco County

The nearest county rated sinkhole country is Emery County, UT, about 150 miles southwest. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Garfield County, CO 30 mi southeast · 15% at surface
Moffat County, CO 44 mi north · 8% at surface
Mesa County, CO 67 mi south · under 1% at surface
Uintah County, UT 70 mi west · 4% at surface
Routt County, CO 73 mi northeast · under 1% at surface
Delta County, CO 79 mi south · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Eagle Valley Fm - evaporitic facies (siltstone), Pennsylvanian in age, covering about under 1% of the county. Next is the Belden Fm at under 1%.

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

Rio Blanco County ranks 29 of 64 in Colorado for soluble rock at the surface, and sits above 56% of US counties on that measure.