Sinkhole risk in Sac County, IA: No soluble rock mapped

No soluble rock mapped

No soluble bedrock mapped.

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

What to do about a house in Sac 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 5 of Sac County's 575 square miles on soluble rock. With about 9,533 residents (17 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 1.3 miles apart, so a pocket smaller than that can be missed or overstated.

Counties around Sac County

The nearest county rated sinkhole country is Knox County, NE, about 143 miles west. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Ida County, IA 21 mi west · 0% at surface
Calhoun County, IA 24 mi east · 0% at surface
Buena Vista County, IA 25 mi north · 0% at surface
Carroll County, IA 27 mi southeast · 0% at surface
Crawford County, IA 28 mi southwest · 0% at surface
Pocahontas County, IA 32 mi northeast · 0% at surface

The rock underneath

The largest mapped soluble unit here is the Meramec Series (limestone), Late Mississippian in age, covering about under 1% of the county.

Against the rest of Iowa

Sac County ranks 83 of 99 in Iowa for soluble rock at the surface, and sits above 0% of US counties on that measure.