Glines Canyon Dam: The History and Removal of a Concrete Giant
Located deep within the lush landscapes of Olympic National Park in Clallam County, Washington, the Glines Canyon Dam (also known as the Upper Elwha Dam) stood for nearly a century as a testament to early 20th-century engineering. A massive concrete arch dam, it played a pivotal role in the region's power generation before becoming the center of one of the most ambitious environmental restoration projects in history.
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The Engineering and Purpose of the Dam
Construction of the Glines Canyon Dam began in 1925 and was completed in 1927. Designed by a team including P.M. Thebo, W.B. McMillan, W.A. Whitmire, H.R. Stevens, and H. Schorer, and built by Thebo, Starr, & Anderson Inc., the structure reached a height of 210 feet (64 m). Its primary purpose was to impound the Elwha River, creating the Lake Mills reservoir.
The dam supported the Glines Canyon Hydroelectric Power Plant, which had an installed capacity of 13.3 MW. Beyond its utility, the power plant was recognized for its Classical Revival architectural style and was added to the U.S. National Register of Historic Places on December 15, 1988, as part of the Hydroelectric Power Plants in Washington State, 1890--1938 MPS.
Key Facts
- Location: Elwha River, Olympic National Park, Clallam County, Washington.
- Height: 210 feet (64 m), making it the tallest dam ever intentionally breached as of 2025.
- Reservoir: Created Lake Mills with a surface area of 415 acres (168 ha).
- Capacity: Total reservoir capacity was 40,500 acre-feet (50,000,000 m).
- Lifespan: Operational from 1927 until its demolition in 2014.
- Historical Status: Listed on the National Register of Historic Places (NRHP reference No. 88002742).
The Path to Restoration
The Glines Canyon Dam was situated 13 miles (21 km) upriver from the mouth of the Elwha River at the Strait of Juan de Fuca and approximately 8 miles (13 km) upriver from the smaller Elwha Dam. Both structures were located within the boundaries of Olympic National Park, which was established in 1938.
To restore the natural flow of the Elwha River and its ecosystem, the National Park Service undertook a massive demolition project. The Elwha Dam was removed first between 2011 and 2012, followed by the demolition of the Glines Canyon Dam in 2014. Until the restoration of the lower Klamath River in the 2020s, this project stood as the largest dam removal in history.
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Technical Specifications Summary
| Feature | Detail |
|---|---|
| Dam Type | Concrete Arch |
| Height | 210 ft (64 m) |
| Reservoir Name | Lake Mills |
| Surface Area | 415 acres (168 ha) |
| Power Capacity | 13.3 MW |
| Construction Period | 1925–1927 |
| Demolition Year | 2014 |
Frequently Asked Questions
Where exactly was the Glines Canyon Dam located?
It was located on the Elwha River along Olympic Hot Springs Road, approximately 11 miles (18 km) southwest of Port Angeles in Olympic National Park, Clallam County, Washington.
Why was the dam demolished?
The dam was demolished by the National Park Service as part of a larger effort to restore the Elwha River to its natural state.
What record does the Glines Canyon Dam hold?
As of 2025, it is the tallest dam ever to be intentionally breached.
Was the dam considered historically significant?
Yes, the Glines Canyon Hydroelectric Power Plant was listed on the U.S. National Register of Historic Places in 1988 due to its Classical Revival architectural style.
How did its removal compare to other projects?
The removal of the Glines Canyon and Elwha dams was the largest dam removal project in history until the restoration of the lower Klamath River in the 2020s.