The Jefferson River is a less-popular, less-crowded fly fishing river known for its brown trout. It starts at the confluence of the Big Hole River and the Beaverhead River and flows about 25 miles to the town of Cardwell. It flows gently through meadows and farmland. At 200 feet wide on average, it can be waded or floated. Below Cardwell, the river runs through Jefferson Canyon for about 12 miles to the town of Sappington. The canyon can be a nice place to fish due to cooler waters from canyon wall shade. Access is provided by SR10.
The lower section beyond Sappington is a 10 mile stretch before the river end at the Three Forks confluence.
The best fly fishing on the Jefferson River is usually in the spring or fall when the water temperature is not too warm.
Overall, Jefferson River is the 10th most popular fly fishing river of all 21 fly fishing spots in Montana.