Sinkhole risk in Clark County, ID: 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: 14%
At or near the surface: 14%
Buried under cover: 0%

What to do about a house in Clark County

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

That works out to roughly 245 of Clark County's 1,763 square miles on soluble rock, 245 of them with the rock at or near the surface. With about 794 residents (0 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 252 map points about 2.6 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Clark County

The nearest county rated sinkhole country is Emery County, UT, about 374 miles south. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Jefferson County, ID 34 mi south · 0% at surface
Fremont County, ID 43 mi east · 9% at surface
Madison County, ID 49 mi southeast · 5% at surface
Butte County, ID 58 mi southwest · 24% at surface
Beaverhead County, MT 64 mi northwest · 10% at surface
Teton County, ID 68 mi southeast · 7% at surface

The rock underneath

The largest mapped soluble unit here is the Limestone, shale, siltstone, chert, and conglomerate; Mississippian western turbiditic flysch to eastern shallow-water carbonates; east-central Idaho (limestone), Mississippian in age, covering about 8% of the county. Next is the Limestone, dolostone, sandstone, siltstone, and chert; Lower Permian to Lower Pennsylvanian marine continental-shelf deposits; east-central Idaho at 6%.

Against the rest of Idaho

Clark County ranks 11 of 44 in Idaho for soluble rock at the surface, and sits above 71% of US counties on that measure.