Sinkhole risk in Garfield 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: 15%
At or near the surface: 15%
Buried under cover: 0%

What to do about a house in Garfield County

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

That works out to roughly 433 of Garfield County's 2,947 square miles on soluble rock, 433 of them with the rock at or near the surface. With about 63,167 residents (21 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 564 map points about 2.3 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: why gypsum and salt move faster than limestone, and how these percentages are measured.

Counties around Garfield County

The nearest county rated sinkhole country is Emery County, UT, about 156 miles west. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Rio Blanco County, CO 30 mi northwest · 1% at surface
Mesa County, CO 50 mi southwest · under 1% at surface
Delta County, CO 51 mi south · 0% at surface
Pitkin County, CO 59 mi southeast · 5% at surface
Eagle County, CO 65 mi east · 22% at surface
Moffat County, CO 72 mi north · 8% at surface

What Garfield County is built on

The largest mapped soluble unit here is the Leadville Limestone, Gilman Sandstone, Dyer Dolomite, and Parting Fm (limestone), Devonian-Ordivician in age, covering about 4% of the county. Next is the Belden Fm at 3%.

2% 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

Garfield County ranks 9 of 64 in Colorado for soluble rock at the surface, and sits above 71% of US counties on that measure.