Bonneville Dam

Bonneville Lock and Dam ( /ˈbɒnɨvɨl/) consists of several run-of-the-river dam structures that together complete a span of the Columbia River between the U.S. states of Oregon and Washington at River Mile 146.1. The dam is located 40 miles (64 km) east of Portland, Oregon, in the Columbia River Gorge. The primary functions of Bonneville Lock and Dam are electrical power generation and river navigation. The dam was built and is managed by the United States Army Corps of Engineers. Electrical power generated at Bonneville is distributed by the Bonneville Power Administration. Bonneville Lock and Dam is named for Army Capt. Benjamin Bonneville, an early explorer credited with charting much of the Oregon Trail. The Bonneville Dam Historic District was designated a National Historic Landmark District in 1987.


In 1896, prior to this damming of the river, the Cascade Locks and Canal were constructed, allowing ships to pass the Cascades Rapids, located several miles upstream of Bonneville.

Prior to the New Deal, development of the Columbia River with flood control, hydroelectricity, navigation and irrigation was deemed as important. In 1929, the US Army Corps of Engineers published the 308 Report that recommended 10 dams on the river but no action was taken until the Franklin D. Roosevelt administration and the New Deal. Now at this time, America was in the Great Depression, and the dam's construction provided jobs and other economic benefits to the Pacific Northwest. Inexpensive hydroelectricity gave rise, in particular, to a strong aluminum industry. During the New Deal and funded from the Public Works Administration, in 1934, two of the larger projects were started, the Grand Coulee Dam and the Bonneville Dam. 3,000 workers in non-stop eight-hour shifts, from the relief or welfare rolls were paid 50-cents an hour for the work on the dam as well as raising local roads for the reservoir.

To create the Bonneville Dam and Lock, The Army Corps of Engineers first built one of the of the largest scale models in history of the purposed dam, the section of river it was to be located on, and its various components to aid in the study of the construction. First a new lock and a powerhouse was constructed which were on the south (Oregon) side of Bradford Island, and a spillway on the north (Washington) side. Coffer dams had to be built in order to block half of the river and clear a construction site where the foundation could be reached. These projects, part of the Bonneville Dam were completed in 1937.

Both the cascades and the old lock structure were submerged by the Bonneville Reservoir, also known as Lake Bonneville, the reservoir that formed behind the dam. The original navigation lock at Bonneville was opened in 1938 and was, at that time, the largest single-lift lock in the world. Although the dam began to produce hydroelectricity in 1937, Commercial electricity began its transfer from the dam in 1938.

A second powerhouse (and dam structure) was started in 1974 and completed in 1981. The second powerhouse was built by widening the river channel on the Washington side, creating Cascades Island between the new powerhouse and the original spillway. The combined electrical output of the two power houses at Bonneville is now over 1 million kilowatts.

Despite its world record size in 1938, Bonneville Lock became the smallest of seven locks built subsequently at different locations upstream on the Columbia and Snake Rivers; eventually a new lock was needed at Bonneville. This new structure was built on the Oregon shore, opening to ship and barge traffic in 1993. The old lock is still present, but is no longer used.

Dimensions and statistics

  • Owner: U.S. Army Corps of Engineers, Portland District
  • Location: On Columbia River about 40 miles upstream from Portland, Oregon
  • First Powerhouse – Constructed in 1933-37; Dam 313 m (1,027 ft) long x 77 feet (23 m) high forebay; 10 generators with an nominal total output capacity of 526.7 MW; Overload capacity 577 MW.
  • Spillway – Constructed 1933-37; 18 gates over a length of 442 m (1,450 ft); maintains the reservoir (upriver) usually 18 m (59 ft) above the river on the downstream side;
  • Second Powerhouse – Constructed 1974-82; Dam 300.5 m (986 ft) long x 77 feet (23 m) high forebay; 8 generators (plus two at fish ladders) with a nominal total generating capacity of 558.2 MW; Overload capacity 612 MW.
  • Bonneville Lock – Constructed from 1987 to 1993 at a cost of $341 million; 26 m (85 ft) wide, 206 m (676 ft) long; transit time is approx. 30 minutes. Replaced earlier smaller lock built 1938.
  • Lake Bonneville – 77 km (48 mi) long reservoir on the Columbia River created by Bonneville Dam; part of the Columbia-Snake Inland Waterway.

It was declared a National Historic Landmark in 1987.

Environmental and social implications

The Bonneville Dam blocked the migration of white sturgeon to their upstream spawning areas. Sturgeon still spawn in the area below the dam and the lower Columbia River supports a healthy sturgeon population. Small very depressed populations of white sturgeon persist in the various reservoirs upstream.

To cope with fish migration problems, the dam features fish ladders to help native salmon and steelhead get past the dam on their journey upstream to spawn. The large concentrations of fish swimming upstream serves as a tourist attraction during the spawning season. California Sea Lions are also attracted to the large number of fish, and are often seen around the base of the dam during the spawning season. By 2006, the growing number of crafty sea lions and their impact on the salmon population have become worrisome to the Army Corps of Engineers and environmentalists. Historically, pinnipeds such as sea lions and seals hunted salmon in the Columbia River as far as The Dalles and Celilo Falls, 200 miles (320 km) from the sea, as remarked upon by people such as George Simpson in 1841.

Electricity controversy

Creating electricity was sensitive at the time of the Bonneville Dam's construction. Constructed with federal dollars, the Franklin D. Roosevelt administration wanted the electricity to be a public source of power and prevent energy monopolies. Advocates for private sale of the electricity were of course opposed to this as they did not want the government to interfere. In 1937, the Bonneville Project Act was signed by Roosevelt, giving the dam's power over to the public and creating the Bonneville Power Administration (BPA). A rate of $17.50 per kilowatt-year was maintained for the next 28 years by the BPA.

In popular culture

In his song Roll on, Columbia, the folk singer, Woody Guthrie, spoke of Bonneville as follows:

Taking the tour

The fish hatchery and dam are open year-round from 9:00 am to 5:00 pm. It is best to visit the dam in the months of April through September when the salmon are more abundant.

There are fish viewing windows and visitors' centers on both the Oregon and Washington sides of the dam. Because of security concerns, visitors may be required to show ID, and it is not possible to cross the entire dam. During most of the year, more fish use the Washington shore fish ladders, so fish viewing may be better on the Washington side of the dam.

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