SinkholeOdds

Sinkhole risk in Bonneville County, ID: Pockets of it

Pockets of it

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

On soluble rock
17%
At or near the surface
17%
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 325 of Bonneville County's 1,866 square miles on soluble rock, 325 of them with the rock at or near the surface. With about 133,644 residents (72 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 241 map points about 2.8 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 Bonneville County

The nearest county rated sinkhole country is Emery County, UT, about 307 miles south. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

What Bonneville County is built on

The largest mapped soluble unit here is the Siltstone, evaporites, and redbeds; Late Jurassic Cordilleran retroarc-foreland-basin deposits; southeastern Idaho (siltstone), Late Jurassic in age, covering about 5% of the county. Next is the Shale, limestone, and sandstone; Triassic marine to non-marine epicontinental deposits (subunits are TRl and TRu) at 4%.

5% of the county sits on gypsum or salt, which dissolves in years rather than millennia. That share matters more than its size suggests.

Against the rest of Idaho

Bonneville County ranks 8 of 44 in Idaho for soluble rock at the surface, and sits above 73% of US counties on that measure.