Sinkhole risk in Sully County, SD: No soluble rock mapped

No soluble rock mapped

No soluble bedrock mapped.

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

What to do about a house in Sully County

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

Across 1,007 square miles, under one square mile of Sully County maps onto soluble rock. With about 1,468 residents (1 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 351 map points about 1.7 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 Sully County

The nearest county rated sinkhole country is Boyd County, NE, about 143 miles southeast. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Potter County, SD 24 mi north · 0% at surface
Hughes County, SD 25 mi south · 0% at surface
Hyde County, SD 35 mi east · 0% at surface
Stanley County, SD 37 mi southwest · 0% at surface
Dewey County, SD 45 mi northwest · 0% at surface
Walworth County, SD 49 mi north · 0% at surface

Against the rest of South Dakota

Sully County ranks 60 of 66 in South Dakota for soluble rock at the surface, and sits above 0% of US counties on that measure.