Shhhh. Don’t tell anyone, but Lake Koocanusa is the best kept secret in all of Montana. 

Here, in the far north of the United States, tucked into the northwestern end of Montana, is the long, narrow Lake Koocanusa. This lake is actually a man-made reservoir, created by the damming of the Kootenai (or, alternatively, Kootenay) River in the late 1960’s and early 1970’s. The dam that was built was named Libby Dam, after the town of Libby, which is a few miles away. The Army Corps of Engineers formed Lake Koocanusa to help control major flooding problems. The lake is also used for hydroelectricity, and supplies power for many communities in Montana and various other states.

Lake Koocanusa stretches to a length of ninety miles. About half of the lake lies in Montana; the rest reaches up into the Canadian province of British Columbia. One of the lake’s interesting landmarks is the Koocanusa Bridge, which was built across the width of the lake. At 2,437 feet, the Koocanusa Bridge is the longest bridge in Montana.   Technically a reservoir, there are no homes on the lake (on the U.S. side), only two small marinas, and very little traffic on this beautiful emerald lake.

Lake Koocanusa’s unique name has an interesting origin. When the reservoir was formed, its name was determined by a contest. The winner of the contest was Alice Beers, who came up with the name Koocanusa. How did she form such an interesting word? She took the koo from Kootenai River, added on can to stand for Canada, and, finally, put on the initials usa for the United States of America.

This 90-mile-long lake provides excellent fishing and boating opportunities. Species of fish include rainbow and cutthroat trout, whitefish, kokanee, and burbot (Ling cod), and streams draining into the lake offer good fishing for brook trout.

Looking for the most scenic drive in Montana?

Look no further! Driving along Lake Koocanusa from Eureka to Libby offers views that rivals Highway 1 in California. A few miles beyond Rexford, Highway 37 reaches the eastern shore of Lake Koocanusa, which it follows closely for the next forty-plus miles until reaching Libby Dam. This stretch of the Lake Koocanusa Byway is, by far, the most scenic. The lake is frequently visible, and the large size of the lake allows for sweeping vistas of the Salish and Purcell Mountains. Numerous pullover spots also exist and are excellent places to stop for pictures, or just for a picnic.

Another highlight of this segment of the drive is the Koocanusa Bridge, the longest and highest bridge in Montana. With a length of 2,437 feet long, and standing more than 270 feet (depending on water levels) above Lake Koocanusa, the views from the top of the bridge are excellent. A small parking area is available off the highway, and sidewalks on the bridge allow passers-by to stop and walk out onto the middle of the bridge. Those looking for a find spot to photograph Lake Koocanusa should definitely plan to stop here.

The Lake Koocanusa Scenic Byway, which is a federally designated National Forest Scenic Byway, is a paved sixty-seven mile drive in Northwest Montana that runs between Eureka and Libby.  Make sure to drive through Libby to the Kootenai Falls – one of the most sacred and beautiful spots in all of Montana.

After meandering along the eastern shoreline of Lake Koocanusa for forty miles, the byway reaches Libby Dam. With a height of 422 feet and a length of 3055 feet, Libby Dam is large, even by western standards. At the base of the dam are a visitor center and a recreation site. During the summer months, tours are available of the dam. Those in search of trophy trout will also want to stop at the dam, as the Kootenai River immediately below Libby Dam is home to some of the state’s largest rainbow trout.

Lake Koocanusa
Lake Koocanusa is home to a variety of fish species. Sport fish include rainbow trout, west slope cutthroat, brook trout, kokanee salmon (blueback), burbot (ling), whitefish and Kamloops (a strain of rainbow trout). The lake has a maximum depth of 370 feet. A valid Montana fishing license is required to fish any Montana waters.