Sinkhole risk in Skagit County, WA: No soluble rock mapped

No soluble rock mapped

No soluble bedrock mapped.

On soluble rock: under 1%
At or near the surface: under 1%
Buried under cover: 0%

What to do about a house in Skagit County

No soluble bedrock is mapped here, so natural sinkholes are unlikely. Collapses from broken pipes or old mines are a separate risk.

That works out to roughly 10 of Skagit County's 1,730 square miles on soluble rock, 10 of them with the rock at or near the surface. With about 132,736 residents (77 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 311 map points about 2.4 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 Skagit County

The nearest county rated sinkhole country is Emery County, UT, about 856 miles southeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Whatcom County, WA 24 mi north · under 1% at surface
Snohomish County, WA 30 mi south · 0% at surface
Island County, WA 46 mi southwest · 0% at surface
San Juan County, WA 59 mi west · 4% at surface
King County, WA 69 mi south · 0% at surface
Chelan County, WA 70 mi southeast · 0% at surface

What Skagit County is built on

The largest mapped soluble unit here is the Carboniferous-Permian sedimentary and volcanic rocks (greenstone), Devonian to Permian but Triassic in Asotin Co in age, covering about under 1% of the county.

Against the rest of Washington

Skagit County ranks 6 of 39 in Washington for soluble rock at the surface, and sits above 53% of US counties on that measure.