Elwha Ecosystem Restoration - The Dams

The Dams

The primary function of this project is the removal of the 108 ft (33 m) Elwha Dam and the 210 ft (64 m) Glines Canyon Dam from the Elwha River on the Olympic Peninsula of Washington state.

Elwha Dam was built from 1910 to 1912 by Thomas Aldwell. The dam blocked passage for migrating fish, limiting them to the lower 4.9 miles (7.9 km) of river below the dam. In 1927 Glines Canyon Dam was built 7 miles (11 km) upriver of Elwha Dam.

Olympic National Park came into existence in 1938. In 1940, the park's boundaries were expanded to include Glines Canyon Dam and Lake Mills. The presence and operation of the dam was inconsistent with National Park Service policies to "...restore natural aquatic habitats and the natural abundance and distribution of native aquatic species, including fish, together with the associated terrestrial habitats and species", and with Olympic National Park objectives to "...conserve, maintain, and restore, where possible, the primary natural resources of the park and those ecological relationships and processes that would prevail were it not for the advent of modern civilization".

This created a precarious situation where a national park, tasked with preserving natural ecosystems, had a man-made system within its boundaries.

When Elwha Dam was built it was secured to the walls of the bedrock canyon, but not the bedrock underlying the river substrate. In 1912, shortly after the reservoir (Lake Aldwell) filled, pressure at the base of the dam built up so much that the foundation of the dam blew out. The void under the dam was plugged by adding fill material to the river below and upstream of the dam. Elwha Dam became operational in 1913. Because of this and other reasons, this dam has never been federally licensed to operate.

A Washington State law established in 1890 required fish passage devices on dams "wherever food fish are wont to ascend". Thomas Aldwell ignored the requirement. Fish Commissioner Leslie Darwin offered to waive that requirement if Aldwell built a fish hatchery adjoining Elwha Dam. Although Aldwell initially balked at this proposal, a fish hatchery was built and began operation in 1915. The hatchery was a fiasco. Its managers were unable to successfully rear fish. It was closed in 1922.