The Clark Fork rises just south of Butte and flows north past Deer Lodge before turning west toward Missoula and ultimately the Columbia. The stretch around town offers good trout fishing — brown and rainbow trout dominate, with the occasional cutthroat — and most of it is wadeable from public access points either side of I-90.
The upper Clark Fork was for decades one of the most polluted rivers in the United States, contaminated by mining waste from the Berkeley Pit at Butte; a major Superfund clean-up over the last twenty years has restored much of the channel and the fishery has recovered with it. Local outfitters in Deer Lodge run guided float trips between June and October. Cottonwood galleries along the banks make for pleasant walking and birdwatching even if you don't fish.