Sinkhole risk in Lake County, CA: 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: 2%
At or near the surface: 2%
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 28 of Lake County's 1,255 square miles on soluble rock, 28 of them with the rock at or near the surface. With about 67,764 residents (54 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 536 map points about 1.5 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Lake County

The nearest county rated sinkhole country is Emery County, UT, about 645 miles east. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Colusa County, CA 28 mi east · 0% at surface
Glenn County, CA 39 mi northeast · 0% at surface
Sonoma County, CA 41 mi south · 0% at surface
Mendocino County, CA 44 mi northwest · 0% at surface
Napa County, CA 47 mi southeast · 2% at surface
Yolo County, CA 54 mi southeast · 0% at surface

What Lake County is built on

The largest mapped soluble unit here is the Franciscan Complex, unit 1 (Coast Ranges) (sandstone), Jurassic to Cretaceous in age, covering about 2% of the county. Next is the Upper Cretaceous marine rocks, unit 1 (Upper Great Valley Sequence) at under 1%.

Against the rest of California

Lake County ranks 12 of 58 in California for soluble rock at the surface, and sits above 58% of US counties on that measure.