Sinkhole risk in Jefferson 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: 2%
At or near the surface: 2%
Buried under cover: 0%

What to do about a house in Jefferson County

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

That works out to roughly 13 of Jefferson County's 764 square miles on soluble rock, 13 of them with the rock at or near the surface. With about 578,533 residents (757 per square mile), most of the county is built up, so a mapped unit is likely to sit under somebody's street. The figures come from 303 map points about 1.6 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: how these percentages are measured, and the warning signs that apply anywhere.

Counties around Jefferson County

The nearest county rated sinkhole country is Dawes County, NE, about 243 miles northeast. 2 of the 6 closest counties land in the same band; the ground changes quickly around here.

Denver County, CO 23 mi northeast · 0% at surface
Clear Creek County, CO 24 mi west · 0% at surface
Douglas County, CO 24 mi southeast · 1% at surface
Gilpin County, CO 25 mi northwest · 0% at surface
Broomfield County, CO 28 mi north · 0% at surface
Boulder County, CO 37 mi north · 4% at surface

The rock underneath

The largest mapped soluble unit here is the Lykins Fm and Lyons Sandstone (sandstone), Triassic-Permian in age, covering about under 1% of the county. Next is the Colorado Group at under 1%.

Against the rest of Colorado

Jefferson County ranks 27 of 64 in Colorado for soluble rock at the surface, and sits above 57% of US counties on that measure.