Sinkhole risk in Missoula County, MT: 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
- 12%
- At or near the surface
- 12%
- 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 298 of Missoula County's 2,593 square miles on soluble rock, 298 of them with the rock at or near the surface. With about 122,546 residents (47 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 589 map points about 2.1 miles apart, so a pocket smaller than that can be missed or overstated.
Read next: how these percentages are measured, and the warning signs that apply anywhere.
Counties around Missoula County
The nearest county rated sinkhole country is Fall River County, SD, about 570 miles southeast. 3 of the 6 closest counties land in the same band; the ground changes quickly around here.
- Lake County, MT 43 mi north · 15% at surface
- Powell County, MT 47 mi east · 13% at surface
- Granite County, MT 49 mi southeast · 17% at surface
- Mineral County, MT 57 mi west · 37% at surface
- Ravalli County, MT 66 mi south · 5% at surface
- Lewis and Clark County, MT 71 mi east · 25% at surface
Which formation it is
The largest mapped soluble unit here is the Piegan group (carbonate), Middle-Proterozoic in age, covering about 7% of the county. Next is the Wallace formation at 2%.
Against the rest of Montana
Missoula County ranks 16 of 56 in Montana for soluble rock at the surface, and sits above 69% of US counties on that measure.
- Meagher County 49%
- Mineral County 37%
- Judith Basin County 33%
- Lincoln County 29%
- Broadwater County 27%