The Clark Fork at Thompson Falls is a broad, powerful river running through a narrow canyon, and it holds a productive fishery in the stretches above and below the dam. Brown trout and rainbow trout are the main targets, with fish in the 12–18 inch range being typical and occasional larger ones turning up in the deeper pools. The river fishes best in late spring and again in autumn, when temperatures moderate and hatches become reliable. Midsummer can be productive early in the morning before the heat sets in.
Floating the river gives access to runs that bank fishing cannot reach, and the canyon walls make for spectacular scenery regardless of whether the fish are cooperating. Several outfitters in the region run guided trips on the Clark Fork. The reservoir above the dam is productive for warm-water species including largemouth bass, which were stocked decades ago and have established themselves in the slack water. A Montana fishing license is required; regulations on the Clark Fork have changed in recent years due to concerns about bull trout, so check the current Montana Fish, Wildlife and Parks rules before you go.