The flooding event at the end of the movie O Brother Where Art Thou was not just a fictional occurrence. In fact, it was a common phenomenon in the 19th and 20th centuries as river valleys in the American West were dammed up for economic and electrification purposes. One such case was the Elwha river in Washington State in the 1910s. The construction of the Elwha Dam provided economic benefits for the region but also blocked off a significant portion of the river, preventing salmon from completing their annual spawning journey.
After years of legal battles led by the Lower Elwha Klallam Tribe, the largest dams on the river today are now the ones made by beavers. In the book “Eat, Poop, Die: How Animals Make Our World” by Joe Roman, the author discusses the recovery of nature when a migration barrier like the Elwha Dam is removed. The book explores how nutrients flow through the food web in the Pacific Northwest and how it is impacted by migratory salmon.
The Elwha Dam, built in 1910, was one of the first high-head dams in the region and was intended to provide electric power to Port Angeles. However, it blocked off most of the river’s watershed from the ocean, severely impacting salmon populations. Concerns about the dam’s effect on native salmon grew in the 1980s, leading the Lower Elwha Klallam Tribe to file a motion to stop the relicensing of the dam. The dams violated the tribe’s fishing rights outlined in the 1855 Treaty of Point No Point.
In 1992, Congress passed the Elwha River Ecosystem and Fisheries Restoration Act, authorizing the removal of the Elwha Dam and the Glines Canyon Dam. The demolition of the Elwha Dam, which cost $350 million and took three years, was the largest dam-removal project in history. The removal of the dams had a significant impact on the river’s ecosystem. Bull trout, landlocked for over a century, started swimming back to the ocean. Chinook salmon populations doubled, and steelhead trout numbers increased.
The removal of the dams also had positive effects on surrounding wildlife. The American dipper, a river bird, benefited from the increase in marine-derived nutrients. Songbird abundance and diversity increased with the number of salmon in nearby British Columbia. Migratory patterns that had been dormant were rekindled, with Pacific lamprey, bull trout, and rainbow trout returning to the river.
The success of the Elwha dam-removal project has sparked interest in removing other aging dams. Plans are in place to remove the Enloe Dam in Washington, which would open up river habitat for steelhead and Chinook salmon. Removing the dams could also benefit critically endangered killer whales off the coast of the Pacific Northwest, as salmon is a crucial food source for them.
Other dam-removal projects are also underway to restore salmon migration. In Northern California, the Klamath River’s salmon run has declined significantly due to the construction of eight dams. Four of these dams are scheduled to be removed in the coming years. The Snake River dams in Washington State are also being considered for breaching to save endangered salmon.
On the other hand, beaver dams are proving to be beneficial for salmon. Beaver dams create slow-water habitats that are critical for juvenile salmon. In Washington, beaver ponds help cool the streams, making them more productive for salmon. In Alaska, the ponds are warmer and aid in the metabolization of salmon’s food. Unlike concrete dams, beaver dams are dynamic, allowing salmon to easily travel through them.
Overall, the removal of the Elwha Dam has had a significant positive impact on the river’s ecosystem. It has provided hope for the removal of other aging dams and the restoration of salmon migration. Additionally, the role of beaver dams in supporting salmon populations highlights the importance of natural processes in maintaining a healthy ecosystem.
