Libby Dam and Lake Koocanusa

Libby Dam and Lake Koocanusa - Quick Facts

Libby Dam was authorized by Congress in the 1950 Flood Control Act for hydropower and flood protection, and construction was completed in 1973. The dam is located on the Kootenai River, 17 miles upstream of Libby, Montana.
The reservoir behind the dam, Lake Koocanusa, extends 90 miles upstream into British Columbia, Canada.
Libby Dam is the fourth dam constructed under the Columbia River Treaty between the U.S. and Canada. The other three treaty projects are located in Canada.

Project Description

• Stream: Kootenai River (RM 221.9)
• Location: Libby, Montana
• Owner: U.S. Army Corps of Engineers, Seattle District
• Authorized Purposes: Flood Control, Hydropower (1950 Flood Control Act)
• Other Purposes: Recreation, Fish and Wildlife, Water Quality
• Type of Project: Storage
• Authorized Flood Storage: 4,980,000 acre-feet

Hydrologic Data

• Drainage area = 8,985 sq mi
• Maximum historical peak discharge = 130,000 cfs (1894)
• Lake Elevation (NGVD29)
• Maximum pool = 2,459.0 ft
• Full pool = 2,459.0 ft (749.5 meters)
• Minimum pool = 2,287.0 ft (697.0 meters)
• Usable Storage (2,287.0 to 2,459.0) = 4,979,500 AF
• Surface area at full pool: 46,500 acres (18,830 hectares)
• Total storage capacity: 5,869,000 acre-feet (7.2 kilometers³)
• Usable storage capacity: 4,980,000 acre-feet (6.1 kilometers³)

Powerhouse

• Number of units = 5
• Nameplate capacity = 525 MW
• Currently installed: 5 units at 120 MW total 600 MW
• Overload capacity = 604 MW
• Hydraulic capacity = 24,100 cfs
• Designed ultimate installation: 8 units at 105 MW total 840 MW
• Date power commercially available: August 24, 1975
• Head at full pool: 107.0 meters (352 feet)
• Maximum turbine discharge of 5 units at full pool: 745.6 meters3/sec (26,500 cfs)

Dam

• Libby
• Completed: 1973
• Height: 432 feet
• Length: 2,887 feet
• Features: powerhouse, spillway
• Deck Elevation: 753.5 meters (2,472 feet)
• Length: 916.0 meters (3,055 feet)
• Approximate height above foundation: 112.8 meters (370 feet)
• Maximum spillway capacity: 4,106 meters3/sec (145,000 cfs)
• Maximum low level outlets capacity: 1,730 meters3/sec (61,000 cfs)

Authorized Purposes

Hydropower

Libby Dam has 5 turbine units and a total generating capacity of 525 megawatts–enough to power roughly 400,000 homes.

Flood Risk Management

Libby operations for flood risk management are based on a variable flow operating criteria.Lake Koocanusa has nearly five million acre-feet of storage space available for local and regional flood control.

Water Quality

Water quality is monitored and managed consistent with Clean Water Act and state standards for the health of aquatic species.

Recreation

There are nine USACE-managed public recreation areas and visitor facilities at Libby Dam and Lake Koocanusathat provide opportunities for a variety of activities, including fishing, camping, hiking, boating, and dam tours. The U.S. Forest Service manages additional recreation sites along the shores of Lake Koocanusa.

Fish & Wildlife

The Kootenai River, downstream of Libby Dam, is home to two fish species listed for protection under the Endangered Species Act –bull trout (threatened) and white sturgeon (endangered). Libby Dam is operated to provide adequate flows during critical periods for protection of these species. Lake Koocanusais home to a variety of sport fish, including rainbow trout, west slope cutthroat, brook trout, kokaneee salmon, burbot, whitefish, Kamloops trout, and others.