The Dalles Dam

The Dalles Dam is a concrete-gravity run-of-the-river hydroelectric dam spanning the Columbia River between The Dalles, Oregon, and Klickitat County, Washington. Constructed by the United States Army Corps of Engineers and completed in 1957, it is a major component of the Columbia River Basin hydroelectric system. The dam created Lake Celilo, inundating the ancient Celilo Falls fishing site, and serves the primary purposes of power generation, navigation, and flood control.

History

The site's history is deeply intertwined with the indigenous cultures of the Pacific Northwest, most notably the Confederated Tribes of Warm Springs, the Confederated Tribes of the Umatilla Indian Reservation, and the Yakama Nation, for whom Celilo Falls was a vital cultural and economic hub for millennia. Proposals for a dam at the location emerged as part of post-World War II development plans under the broader Columbia Basin Project. Authorization for construction came via the Flood Control Act of 1950, with work beginning in 1952. The dam's completion in 1957 coincided with the dedication of the nearby The Dalles Bridge and marked a significant moment in the region's industrialization, following earlier projects like Bonneville Dam and preceding later ones such as John Day Dam.

Design and construction

The structure is a massive concrete gravity dam, approximately 8,875 feet long and 260 feet high, incorporating a spillway section, a powerhouse, and navigation locks. Its design is characteristic of United States Army Corps of Engineers projects of the era, utilizing over 3 million cubic yards of concrete. A key engineering challenge was managing the immense flow of the Columbia River during construction, which involved the use of cofferdams to divert water. The dam's powerhouse was originally equipped with 22 Francis turbine generators. The associated Lake Celilo extends 24 miles upstream to the foot of John Day Dam. Construction required significant infrastructure, including relocation of segments of the Spokane, Portland and Seattle Railway and U.S. Route 197.

Operations and power generation

Operated by the United States Army Corps of Engineers, with its electricity marketed by the Bonneville Power Administration, the dam is a cornerstone of the Northwest Power Pool. Its powerhouse has a total installed capacity of 1,779 megawatts, making it one of the largest hydroelectric facilities in the Pacific Northwest. The dam operates as a run-of-the-river project, with limited storage capacity, and its generation is integral to meeting regional power demands and providing frequency regulation for the Western Interconnection grid. The facility's eight-unit second powerhouse, completed in the 1970s, added substantial capacity. Its operations are coordinated with other major dams like Grand Coulee Dam and McNary Dam under the Columbia River Treaty.

Environmental and cultural impact

The dam's creation had profound and lasting consequences, most significantly the permanent flooding of Celilo Falls, one of the oldest continuously inhabited sites in North America and a central fishing and trading location for regional Native American tribes. This event, which occurred on March 10, 1957, caused irreparable cultural loss for the Confederated Tribes of Warm Springs, the Confederated Tribes of the Umatilla Indian Reservation, the Yakama Nation, and other Columbia River Inter-Tribal Fish Commission members. Ecologically, the dam, like others on the Columbia River, presents a major barrier to anadromous fish like Chinook salmon and steelhead, impacting their migration and necessitating extensive fish ladder systems. It has also altered river sediment transport and water temperature regimes.

Navigation and economic role

The dam features a large navigation lock, 86 feet wide and 675 feet long, which is a critical link in the Columbia-Snake Inland Waterway, allowing barge traffic to travel from the Pacific Ocean at Astoria, Oregon, to Lewiston, Idaho. This waterway is a vital economic artery for transporting wheat, other agricultural products, and bulk commodities. The dam's pool provides a stable navigation channel and supports local industries, including aluminum production that historically relied on the region's inexpensive hydroelectric power. The facility also contributes to regional flood risk management and provides water for irrigation projects, supporting the agriculture of the Columbia Plateau.

Category:Dams in Oregon Category:Dams in Washington (state) Category:Buildings and structures in Wasco County, Oregon Category:Columbia River