Sinkhole risk in Washington County, MD: Sinkhole country

Sinkhole country

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

On soluble rock: 61%
At or near the surface: 61%
Buried under cover: 0%

The next step for one property

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

That works out to roughly 279 of Washington County's 458 square miles on soluble rock, 279 of them with the rock at or near the surface. With about 157,228 residents (343 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 373 map points about 1.1 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: the signs to look for and how an inspection works, and how these percentages are measured.

Counties around Washington County

The closest county with no soluble rock mapped is Montgomery County, MD, about 46 miles southeast. 1 of the 6 closest counties land in the same band; the ground changes quickly around here.

Berkeley County, WV 16 mi southwest · 44% at surface
Jefferson County, WV 21 mi south · 84% at surface
Franklin County, PA 23 mi north · 44% at surface
Morgan County, WV 24 mi west · 7% at surface
Frederick County, MD 24 mi east · 13% at surface
Fulton County, PA 27 mi northwest · 19% at surface

What Washington County is built on

The largest mapped soluble unit here is the Conococheague Limestone (limestone), Upper Cambrian to Lower Ordovician in age, covering about 20% of the county. Next is the Tomstown Dolomite at 10%.

Against the rest of Maryland

Washington County ranks 1 of 24 in Maryland for soluble rock at the surface, and sits above 90% of US counties on that measure.