Sinkhole risk in Washington County, FL: Sinkhole country

Sinkhole country

Soluble rock at or near the surface across much of the county.

On soluble rock: 97%
At or near the surface: 54%
Buried under cover: 44%

What this means before you buy

Get a sinkhole or geotechnical inspection before buying, building or adding weight to a foundation.

Standard Florida homeowners policies cover only catastrophic ground cover collapse; full sinkhole coverage is a separately priced option insurers must offer.

That works out to roughly 568 of Washington County's 585 square miles on soluble rock, 313 of them with the rock at or near the surface. With about 26,503 residents (45 per square mile), there is effectively nowhere in the county off the soluble rock, town or country. The figures come from 617 map points about 1.0 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Washington County

The closest county with no soluble rock mapped is Gulf County, FL, about 56 miles southeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.

Holmes County, FL 20 mi northwest · 66% at surface
Jackson County, FL 30 mi northeast · 87% at surface
Walton County, FL 30 mi west · 11% at surface
Calhoun County, FL 31 mi southeast · 13% at surface
Bay County, FL 31 mi south · 0% at surface
Geneva County, AL 35 mi north · 51% at surface

The rock underneath

The largest mapped soluble unit here is the Alum Bluff Group (sandstone), Miocene in age, covering about 50% of the county. Next is the Alum Bluff Group at 37%.

Against the rest of Florida

Washington County ranks 23 of 67 in Florida for soluble rock at the surface, and sits above 88% of US counties on that measure.