Southeast of Lowell, the Selway River is an epic 40 mile fly fishing river. Starting from Lowell, a road parallels the north shore for the first 15 miles. At the end of the road, heading upstream into the wilderness area, there is a foot trail along the river (Selway River Trail #4) that follows the Selway River for 50 miles through the Selway Bitteroot Wilderness. The trail runs through remote pine forest and is known for its plentiful rattlesnakes and bears.
The eastern trailhead is located at Paradise Landing (north of Salmon) and the western trailhead is at Race Creek Campground near Lowell.
The river can get quite warm by August, so you will need to work the colder water tributaries.
Plan to see more wildlife than anywhere else in the nation, including mountian lion, moose, black bear, elk and an occasional otter on the Selway River.
Overall, Selway River is the 3rd most popular fly fishing river of all 17 fly fishing spots in Idaho.