Hells Canyon Dam

Hells Canyon Dam
Aerial view from northeast
Location in the United States Show map of the United States Location in Idaho Show map of Idaho
Country	United States
Location	Hells Canyon, Adams County, Idaho / Wallowa County, Oregon
Coordinates	45°14′41″N 116°41′54″W / 45.24472°N 116.69833°W / 45.24472; -116.69833
Opening date	1967; 57 years ago (1967)
Operator(s)	Idaho Power Company
Dam and spillways
Impounds	Snake River
Height	330 ft (100 m)
Reservoir
Creates	Hells Canyon Reservoir
Total capacity	188,000 acre⋅ft (232,000,000 m3)
Catchment area	73,300 sq mi (189,800 km2)
Surface area	3.9 sq mi (10 km2)
Normal elevation	1,650 ft (503 m)
Power Station
Installed capacity	391 MW
Annual generation	2,051.3 GWh

Hells Canyon Dam is a concrete gravity dam in the western United States, on the Snake River in Hells Canyon along the Idaho-Oregon border. At river mile 247, the dam impounds Hells Canyon Reservoir; its spillway elevation is 1,680 feet (512 m) above sea level.

It is the third and final hydroelectric dam of the Hells Canyon Project, which includes Brownlee Dam (1959) and Oxbow Dam (1961), all built and operated by Idaho Power Company. The Hells Canyon Complex on the Snake River is the largest privately owned hydroelectric power complex in the nation, according to the US Energy Information Administration.^[1] The contractor for the Hells Canyon Dam was Morrison-Knudsen of Boise.

The Hells Canyon Dam powerhouse contains three generating units, with a total nameplate capacity of 391 megawatts (MW).^[2] Power generation began with two units in 1967, the third came on line the following year.

Lacking passage for migrating salmon, the three dams of the Hells Canyon Project blocked access by anadromous salmonids to a stretch of the Snake River drainage basin from Hells Canyon Dam up to Shoshone Falls, which naturally prevents any upstream fish passage to the upper Snake River basin.

As built, Hells Canyon Dam is significantly lower than it was originally proposed in the 1940s, with three dams (Hells Canyon, Brownlee Dam and Oxbow Dam) taking the place of a single 710-foot (220 m) high dam.^[3] As proposed by the U.S. Army Corps of Engineers, the Hells Canyon High Dam would have been a straight-profile concrete gravity dam with two gate-controlled tunnel spillways, one in each abutment.

The proposed reservoir was planned to have a capacity of 4,050,000 acre-feet (5.00 km³) with an area of 23,500 acres (36.7 sq mi; 95 km²). The reservoir was to extend 89 miles (143 km) upstream. The power plant was to be capable of generating 850 MW using ten units. The project included provisions for fish hatcheries, with the intention of maintaining salmon runs. Project cost was estimated at $342,076,000.^[4]

The proposals for a publicly built high dam became a big political issue in many Western states. Both of Oregon's senators Wayne Morse and Richard L. Neuberger proposed a public dam, but were blocked.^[5] Many Western moderately pro-civil rights senators supported Southern Democrats in their efforts to water down the 1957 Civil Rights Act in return for southern support for a publicly built high dam.^[6] However the Idaho Senator Frank Church who was a strong supporter of the high dam (whose maiden speech was on the subject), a protege of Lyndon Johnson and a prominent Western liberal Senator who modified the 1957 Act said that "There was never any quid pro quo at all".^[7]

The high dam project was in the end not pursued.

• List of power stations in the United States
• List of dams in the Columbia River watershed

Wikimedia Commons has media related to Hells Canyon Dam.

• Hells Canyon Dam Archived 2008-11-22 at the Wayback Machine, Northwest Power and Conservation Council
• Hells Canyon Complex, Idaho Power