Sinkhole risk in Millard County, UT: Pockets of it

Pockets of it

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

On soluble rock: 18%
At or near the surface: 18%
Buried under cover: 0%

The next step for one property

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 1,215 of Millard County's 6,785 square miles on soluble rock, 1,215 of them with the rock at or near the surface. With about 13,572 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 375 map points about 4.3 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 the signs to look for and how an inspection works.

Counties around Millard County

The nearest county rated sinkhole country is Emery County, UT, about 130 miles east. None of the 6 closest counties land in the same band, so Millard County stands out from its surroundings.

Beaver County, UT 42 mi south · 8% at surface
Juab County, UT 55 mi north · 11% at surface
Piute County, UT 69 mi southeast · 0% at surface
Sevier County, UT 73 mi east · 6% at surface
Iron County, UT 73 mi south · 2% at surface
Sanpete County, UT 88 mi east · 14% at surface

What Millard County is built on

The largest mapped soluble unit here is the Devonian sedimentary rocks in western Utah (dolostone (dolomite)), Devonian to Mississippian in age, covering about 4% of the county. Next is the Upper Cambrian carbonate rocks in western Utah at 2%.

The county also lies over the Sevire Valley, 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 Utah

Millard County ranks 5 of 29 in Utah for soluble rock at the surface, and sits above 73% of US counties on that measure.