Canyon Ferry Dam
Encyclopedia
Canyon Ferry Dam is a concrete gravity dam in a narrow valley of the Missouri River
where the Big Belt Mountains
and the Spokane Hills
merge, approximately 68 miles (109 km) downstream from the confluence of the Gallatin, Madison, and Jefferson Rivers, and about 20 miles (32 km) east of the city of Helena, Montana
. The purpose of the dam is flood control, irrigation, recreation and hydroelectric power.
is located on its central portion and is controlled by four radial gates. It has a maximum discharge of 150000 ft3/s. Adjacent to the spillway is the dam's power plant which contains three 16.5 MW Francis turbine
generators for an installed capacity of 50 MW. Each turbine is fed with water by a 13.5 ft (4 m) diameter penstock
. At a normal elevation of 3797 ft (1,157 m), the reservoir
contains 1891000 acre.ft of water.
Missouri River
The Missouri River flows through the central United States, and is a tributary of the Mississippi River. It is the longest river in North America and drains the third largest area, though only the thirteenth largest by discharge. The Missouri's watershed encompasses most of the American Great...
where the Big Belt Mountains
Big Belt Mountains
The Big Belt Mountains are a section of the Rocky Mountains in the U.S. state of Montana. Situated mainly in the Helena National Forest, the mountains are used for logging and recreation for the surrounding residents. Nearby is Helena, Montana, Canyon Ferry Lake, the Missouri River, Townsend,...
and the Spokane Hills
Spokane Hills
The Spokane Hills, el. , is a set of major foothills of the Big Belt Mountains to the east of Helena, Montana in Lewis and Clark County, Montana. They lie between the Helena Valley and Canyon Ferry Reservoir]...
merge, approximately 68 miles (109 km) downstream from the confluence of the Gallatin, Madison, and Jefferson Rivers, and about 20 miles (32 km) east of the city of Helena, Montana
Helena, Montana
Helena is the capital city of the U.S. state of Montana and the county seat of Lewis and Clark County. The 2010 census put the population at 28,180. The local daily newspaper is the Independent Record. The Helena Brewers minor league baseball and Helena Bighorns minor league hockey team call the...
. The purpose of the dam is flood control, irrigation, recreation and hydroelectric power.
Background
In 1941, the first study for the dam was carried out by the Bureau of Reclamation, the Montana Water Board and Montana Power Co. Known as the Canyon Ferry Unit, the dam and power plant were approved by the Flood Control Act of 1944 which was signed on December 22. Construction began on May 24, 1949 and was completed on June 23, 1954. On December 18, 1953, the power plant's first generator became operational and the other two went online in 1954. The 1949 structure replaced the original Canyon Ferry Dam 1.5 mi (2 km) upstream. The original dam was constructed between 1896 and 1898 by the Helena Water and Electric Power Company. It was a timber crib dam with rock-fill and was 29 ft (9 m) high and 485 ft (148 m) long.Design
The dam is a 225 ft (69 m) tall concrete gravity type has a length of 1000 ft (305 m). The crest of the dam is 20 ft (6 m) while the base is 173 ft (53 m). The dam structure compromises a total of 414400 cu yd (316,832 m³) of concrete. The dam's spillwaySpillway
A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...
is located on its central portion and is controlled by four radial gates. It has a maximum discharge of 150000 ft3/s. Adjacent to the spillway is the dam's power plant which contains three 16.5 MW Francis turbine
Francis turbine
The Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachusetts. It is an inward-flow reaction turbine that combines radial and axial flow concepts....
generators for an installed capacity of 50 MW. Each turbine is fed with water by a 13.5 ft (4 m) diameter penstock
Penstock
A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydraulic turbines and sewerage systems. It is a term that has been inherited from the technology of wooden watermills....
. At a normal elevation of 3797 ft (1,157 m), the reservoir
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
contains 1891000 acre.ft of water.