The major lakes of Southwestern Montana are mainly concentrated along the Madison River drainage. These lakes tend to be on the shallow side and have good populations of Mayflys, making them excellent targets for fly fisherman. Known as "Gulpers", the large Rainbows that feed on these hatches draw anglers from far and wide. Boats or float tubes are very useful here in order to cover more water and reach fish that are rising out of reach from the shore.
Ennis Lake is a man made impoundment of the Madison River in southwestern Montana. A shallow lake, much of the water is less than 8 feet deep. Ennis Lake is well known for its "gulper" hatch of callibaetis and trico mayflies during the summer. Large Browns and Rainbows of over 20" can be taken on the surface during this time.
Harrison Lake is a man-made reservoir located about 45 minutes from Bozeman and Ennis. The lake collects the waters of the North and South Forks of Willow Creek as they pour out of the Tobacco Root Mountains. Best fished from a boat, Harrison Lake contains large Rainbow Trout that average 17"-19". The trout here are known as hard fighters and often produce sizzling runs.
Hebgen Lake runs 16-miles long and the area provides a number of campgrounds. Most of the arms of the lake offer good fly fishing for float tubers. July and August brings the famous "Gulper" hatch, where large Rainbows and Browns feed voraciously on small mayflys during calm days.