Porcupine Rapids is a stretch of rapids in Lemhi County, Idaho, in the Idaho Batholith region. It lies about 40.6 miles west of Salmon and roughly 125.4 miles south of Missoula as the crow flies.
The Idaho Batholith is a maze of steep granite mountains and deep canyons blanketed by lodgepole and ponderosa pine and Douglas fir, with some of the largest roadless areas in the lower 48. Rivers here are wild and fast, dropping through rocky gorges.
There are 6 recorded rapids in Lemhi County. Redside Rapids, is about 1.6 miles away. Cliffside Rapids, is about 6.6 miles away. Ouzel Rapids, is about 7.8 miles away.
Porcupine Rapids is located at 45.1295° N, 114.7264° W. The listing is based on the USGS Geographic Names Information System, one of the sources compiled by the U.S. Geological Survey in its inventory of waterfalls and rapids of the conterminous United States. The position was verified on aerial imagery. Details on trails, parking and access have not been documented for this rapid yet.