Initial phase of building Lower Monumental Dam on the Snake River is completed on February 21, 1969.

  • By Phil Dougherty
  • Posted 12/07/2006
  • Essay 8022
On February 21, 1969, the initial phase of the Lower Monumental Dam is completed and water is allowed to begin filling Lake Herbert G. West above the dam. The dam is the second dam of a series of four dams built in the Lower Snake River Project. The environmental controversy over damage to salmon involved in damming the Snake River caused by the four dams continues to the present day (2006). However, the construction of Lower Monumental Dam is particularly remembered for causing the inundation of the Marmes Rockshelter, an important Stone Age archaeological site. The dam is located six miles south of Kahlotus, Washington (Franklin County).

The Lower Snake River Dams

For years there had been a dream among those living near the Snake River of opening the river to make it navigable to the Pacific Ocean. Later the dream grew to include utilizing dams to provide an inexpensive power source. The dream became a reality in 1945 when Congress authorized the Lower Snake River Project. The project involved the construction of four dams along the Lower Snake River in Washington state: Ice Harbor Dam, Lower Monumental Dam, Little Goose Dam, and Lower Granite Dam. Lower Monumental Dam was the second dam in the project.

Lower Monumental Dam, which bridges Franklin and Walla Walla Counties, was named after Monumental Rock, a nearby rock formation in Walla Walla County approximately three miles northeast of the dam. Monumental Rock soars dramatically more than 500 feet above the surrounding terrain. Lewis and Clark named it Ship Rock when they passed it during their 1805-1806 exploration to the Pacific Ocean, but later travelers renamed it Monumental Rock.

Lower Monumental Dam is 3,791 feet long, making it the longest dam of the four dams completed along the Lower Snake River between 1961 and 1975. During its construction, it escaped many -- though not all -- of the environmental protests that accompanied the construction of the first dam in the project, the Ice Harbor Dam. But the protests about the construction of Lower Monumental Dam were relatively mild; the project faced a more serious adversary from President Dwight Eisenhower (1890-1969). When Eisenhower assumed office in 1953 he proclaimed a policy of no new starts for federal multi-purpose dams. This policy was intended to restrict federal spending for river development and to encourage private enterprise as well as state and local government to share in its costs. In the summer of 1960, Washington senator Warren G. Magnuson (1905-1989) did an end-run around Eisenhower in a House-Senate conference committee and obtained an appropriation of one million dollars in start-up funds for Lower Monumental Dam. Construction began in June 1961.

The Walla Walla District of the Corps of Engineers had been responsible for the construction of the Ice Harbor Dam, which by June 1961 was nearly complete. But Walla Walla was also involved in the construction of the John Day Dam on the Columbia River and in another few years would take on responsibility for constructing the Little Goose Dam farther up the Snake River. Because the Walla Walla District had its hands full while the Corps Seattle District was facing possible layoffs, the Corps division engineer made the Seattle District responsible for construction of Lower Monumental Dam in 1962 -- and it became the only dam of the four on the Lower Snake River whose construction was not primarily handled by the Walla Walla District. When the dam was completed in 1969, Seattle turned the operation of Lower Monumental back over to Walla Walla.

The project proceeded smoothly through most of the 1960s. The Corps worked with fishing interests to develop fish passage facilities at the dam, and there were fewer environmental protests than there had been with Ice Harbor or than there would be with the final dam in the project, the Lower Granite Dam. Yet the completion of Lower Monumental Dam and the filling of the reservoir behind it did generate its own unique controversy when it came to preserving the Marmes Rockshelter.

Marmes Rockshelter

The Marmes Rockshelter was an alcove in the rock in the Palouse River Canyon near the mouth of the Palouse River. During the early and mid-1960s archaeological excavations at the site had uncovered evidence of human habitation dating back thousands of years. But the biggest discovery came in April 1968 when human bones later established to be more than 10,000 years old were found at the rockshelter. At that time, they were the oldest human bones found anywhere in the Western Hemisphere. But there was a problem: Lower Monumental Dam was scheduled for completion in December 1968, and the entire site was slated to be covered by 40 feet of water when the reservoir behind the dam filled.

The find at the Marmes Rockshelter and the pending loss of the rockshelter generated considerable publicity all around the country. A mad rush ensued to excavate as much of the site as possible before the site was inundated. A cofferdam was built around the site late in 1968 to keep the site dry once the dam was completed and the reservoir began to fill. However, the cofferdam (a circular structure designed to keep out water) was built on a gravel base, which did not retain water. When the reservoir began to fill in late February 1969, the area supposedly to be protected by the cofferdam filled as fast as the reservoir.

Project Completion

On February 21, 1969, Lower Monumental Dam’s floodgates were closed and the reservoir was allowed to fill; the process took six days. The first vessel passed through Lower Monumental’s locks on April 15 and the first of three generators went on-line on May 28, 1969. The dam was functioning in the summer of 1969, but in July 1969 the Corps reported that the project was 92 percent complete, with work continuing on the powerhouse and installation of mechanical and electrical equipment. The original project cost $177 million. Three additional generators were built at the dam between 1975 and 1981.

Navigation on the river initially increased after the four Snake River dams were completed in 1975, but has since declined more than 30 percent since the late 1980s. The dams have, however, successfully generated plentiful and inexpensive electrical power in the region.

Naming the lake that formed behind Lower Monumental Dam proved to be no easy task. In the 1960s many favored naming it Lake Alice Clarissa Whitman, after the daughter of missionaries Marcus Whitman (1802-1847) and Narcissa (Prentiss) Whitman (1808-1847). Others favored a name more closely related to the Lewis and Clark Expedition. Finally in May 1978 Congress designated the lake as Lake Herbert G. West, named after Herbert G. West (d. 1974), the first managing secretary and early leader of the Inland Empire Waterways Association and, along with Warren G. Magnuson, one of the driving forces behind the development of the Lower Snake River Project. The lake is 28.1 miles long and extends northeast to Little Goose Dam.

Environmental Questions

Lower Monumental Dam was completed just as the environmental movement against the damming of the Snake River began to take shape in 1969. However, the dam has not escaped the controversy and litigation which has resulted since. Dwindling salmon and steelhead runs put the case back in District Court four times between 1994 and 2005, with the court rejecting several fish-recovery plans proposed by the government.

Some dam opponents now (2006) argue the dams should be breached -- something that can only be achieved by Congressional authorization -- but at this time that appears unlikely to happen.

Sources: Controversy, Conflict and Compromise: A History of the Lower Snake River Development (Walla Walla: U.S. Army Corps of Engineers, Walla Walla District, n.d.), website accessed November 24, 2006, (; Online Encyclopedia of Washington State History, “Marmes Rockshelter” (by Cassandra Tate), “Vice President Lyndon B. Johnson dedicates Ice Harbor Dam on May 9, 1962” (by Elizabeth Gibson), (accessed November 22, 2006); “Lower Monumental Lock And Dam -- Lake Herbert G. West,” U.S. Army Corps of Engineers, Walla Walla District, website accessed November 24, 2006, (; “Report of the Secretary of Army On Civil Works Activities For Fiscal Year 1969,” U.S. Army Corps of Engineers, Walla Walla District, website accessed November 24, 2006, ( See Also: Brent A. Hicks, Marmes Rockshelter: A Final Report on 11.000 Years of Cultural Use (Pullman: WSU Press, 2004).

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