Sinkhole risk in Moffat 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: 8%
At or near the surface: 8%
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 375 of Moffat County's 4,743 square miles on soluble rock, 375 of them with the rock at or near the surface. With about 13,142 residents (3 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 378 map points about 3.5 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Moffat County

The nearest county rated sinkhole country is Emery County, UT, about 173 miles southwest. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Rio Blanco County, CO 44 mi south · 1% at surface
Routt County, CO 65 mi east · under 1% at surface
Daggett County, UT 70 mi west · 5% at surface
Garfield County, CO 72 mi south · 15% at surface
Uintah County, UT 76 mi southwest · 4% at surface
Sweetwater County, WY 80 mi northwest · 3% at surface

The rock underneath

The largest mapped soluble unit here is the Morgan Fm and Round Valley Limestone (limestone), Pennsylvanian in age, covering about 3% of the county. Next is the Green River Fm--Tipton Tongue at 2%.

1% 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

Moffat County ranks 13 of 64 in Colorado for soluble rock at the surface, and sits above 66% of US counties on that measure.