Sinkhole risk in Hidalgo County, NM: Mostly deep or small

Mostly deep or small

Some soluble rock, mostly deeply buried or in a small share of the county.

On soluble rock: 2%
At or near the surface: 2%
Buried under cover: 0%

The next step for one property

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 62 of Hidalgo County's 3,439 square miles on soluble rock, 62 of them with the rock at or near the surface. With about 3,966 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 275 map points about 3.5 miles apart, so a pocket smaller than that can be missed or overstated.

Worth reading for this county: why gypsum and salt move faster than limestone, and how these percentages are measured.

Counties around Hidalgo County

The nearest county rated sinkhole country is Eddy County, NM, about 263 miles east. 4 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Cochise County, AZ 60 mi west · 6% at surface
Grant County, NM 62 mi north · 2% at surface
Luna County, NM 62 mi east · under 1% at surface
Greenlee County, AZ 97 mi north · 2% at surface
Graham County, AZ 97 mi northwest · under 1% at surface
Doña Ana County, NM 116 mi east · 6% at surface

The rock underneath

The largest mapped soluble unit here is the Permain and Pennsylvanian rocks, undivided (medium-grained mixed clastic), Permain and Pennsylvanian in age, covering about 2% of the county. Next is the Lower Cretaceous, unidivided at under 1%.

The county also lies over the Pedregosa Basin, a deep salt or gypsum basin. Deep beds rarely cause surface collapse on their own, but wells and mining into them have.

Against the rest of New Mexico

Hidalgo County ranks 26 of 33 in New Mexico for soluble rock at the surface, and sits above 57% of US counties on that measure.