50 Years of the Libby Dam
When you flip a light switch, you’re harnessing the power of water spinning the turbines of 31 dams that make up the Federal Columbia River Power System (FCRPS). The Bureau of Reclamation (BOR) and the Army Corps of Engineers (ACE) operate these hydro projects. The Bonneville Power Administration (BPA) then sells the power to states across the Pacific Northwest.
As a member of Flathead Electric Cooperative, most of the electricity that powers your homes and businesses is BPA hydropower. In 2024, over 70% of our power supply was generated by those 31 FCRPS dams!
You’re probably familiar with the highest dam on the FCRPS, the Hungry Horse Dam, which came online in 1953. We celebrated its 70th anniversary in the December 2023 issue of Light Reading. You might be less familiar with the Libby Dam, which was connected to FCRPS in 1975 and marked its 50th anniversary this year.
Located about 20 minutes east of Libby, the dam impounds the Kootenai River, the third-largest tributary of the Columbia River. On average, the Kootenai River provides about 20% of the total water in the lower Columbia River. Libby Dam was the fourth project constructed under the 1964 Columbia River Treaty between the United States and Canada. The dams envisioned under that Treaty provide hydropower and flood control throughout British Columbia and the Pacific Northwest, benefiting both nations.
Building the Libby Dam was an immense feat. The project required moving the town of Rexford to higher ground, relocating Highway 37, engineering the Koocanusa Bridge (Montana’s longest and highest!), and tunneling through Elk Mountain to create a 7-mile-long railroad tunnel. Known today as the Flathead Tunnel, it remains the second-longest railroad tunnel in the U.S. and third-longest in North America. At the time, tunnel excavation was bid at $43.9M (roughly $439M today) and required 488 working days and 2.1M pounds of explosives to complete.
Once completed, the Kootenai River formed Lake Koocanusa, now an international recreation spot stretching 90 miles, with 42 of those miles in Canada. The name “Koocanusa” symbolizes the partnership between the Kootenai Tribe, Canada, and the U.S.A.
Today, Libby Dam is managed to produce hydroelectric power, provide flood protection, and support downstream FCRPS operations, irrigation, recreation, and environmental stewardship. Its selective withdrawal system allows operators to draw water from varying depths of Lake Koocanusa, helping stabilize downstream water temperatures. Since 1985, the dam has operated five generating units, though the powerhouse was designed for eight. Recently, ACE awarded a contract for a sixth unit, which will enhance daily operational flexibility and improve overall power reliability.
On August 23, 2025, ACE hosted a commemoration marking Libby Dam’s 50 years of service. The dam and visitor center were open for tours and the public enjoyed rare access to the top of the dam. Your Co-op was there to celebrate the dam’s success and its vital contributions to the affordability and reliability of hydropower in Northwest Montana. As we enter the cold, dark nights of the holiday season, we celebrate the incredible gift of hydropower, and the enduring legacy of the Libby Dam.
Libby Dam Fast Facts
- Generating turbines — 5
- Generating capacity — 600 MW capacity
- Water capacity — 4,980,000 acre-feet
- Type — Concrete gravity dam
- Height — 422 feet
- Length — 3,055 feet
- Depth — 370 feet (max. depth of Lake Koocanusa)
