The man-made flood that miraculously saved our heroes at the end of Oh brother, where are you? They were a real occurrence in the 19th and 20th centuries, and quite common, when river valleys throughout the American West were dammed and drowned on the altar of economic progress and electrification. Such was the case of Washington State Elwha River Its dam provided the economic impetus to develop the Olympic Peninsula, but also blocked nearly 40 miles of river from the open ocean, preventing native salmon species from making their annual spawning journey. However, after decades of legal wrangling by the Lower Elwha Klallam Tribe, the largest dams on the river today are of the type built by beavers.
In this week’s Hitting the Books selection, Eat, Poop, Die: How Animals Make Our World, Conservation biologist at the University of Vermont joe roman chronicles how quickly nature can recover when a 108-foot-high migratory barrier is removed from the local ecosystem. This excerpt looks at naturalists and biologists striving to understand how nutrients flow through the Pacific Northwest food web and the myriad ways it is affected by migrating salmon. The book as a whole offers a fascinating look at how the most basic biological functions (yes, poop!) of even a few species can potentially affect life in every corner of the planet.
Extracted from by Eat, Poop, Die: How Animals Make Our World by Joe Roman. Published by Hachette Book Group. Copyright © 2023 by Joe Roman. All rights reserved.
When construction began in 1910, the Elwha Dam was designed to attract economic development to the Olympic Peninsula in Washington, providing electrical power to the growing community of Port Angeles. It was one of the first high-altitude dams in the region, with water moving more than a hundred meters from the reservoir to the river. Before the dam was built, the river supported ten channels of anadromous fish. All five species of Pacific salmon (pink, chum, sockeye, chinook and coho) were found in the river, along with bull trout and rainbow trout. In a good year, hundreds of thousands of salmon would ascend the Elwha to spawn. But contractors never finished the promised fish ladders. As a result, the Elwha isolated most of the ocean basin and 90 percent of the migratory salmon habitat.
Thousands of dams block the world’s rivers, decimating fish populations and clogging nutrient arteries from the sea to mountain springs. Some have fish ladders. Others send fish through concrete walls. Many act as permanent barriers to the migration of thousands of species.
In the 1980s, there was growing concern about the Elwha’s effect on native salmon. Populations had declined by 95 percent, devastating local wildlife and indigenous communities. River salmon are essential to the culture and economy of the Lower Elwha Klallam Tribe. In 1986, the tribe filed a motion through the Federal Energy Regulatory Commission to stop the relicensing of Elwha Dam and Glines Canyon Dam, an upstream reservoir that was even higher than Elwha. By blocking salmon migration, the dams violated the Point No Point Treaty of 1855, in which the Klallams ceded a large portion of the Olympic Peninsula with the stipulation that they and all their descendants would have “the right to fish in areas usual and customary. .” The tribe teamed up with environmental groups, including the Sierra Club and the Seattle Audubon Society, to pressure local and federal officials to remove the dams. In 1992, Congress passed the Elwha River Fisheries and Ecosystem Restoration Act, which authorized the decommissioning of the Elwha and Glines Canyon dams.
The Elwha Dam demolition was the largest dam removal project in history; It cost $350 million and took about three years. Beginning in September 2011, the cofferdams diverted water to the side when the Elwha Dam was dismantled and destroyed. Glines Canyon was more challenging. According to Pess, it took a “glorified jackhammer on a floating barge” to dismantle the sixty-meter reservoir. The barge did not work when the water receded, so new equipment was sent by helicopter. By 2014, most of the dam had collapsed, but rockfalls still blocked fish passage. It took another year of moving rocks and cement before the fish had full access to the river.
The response of the fish was quick, satisfactory and, at times, surprising. Elwha River bull trout, landlocked for more than a century, began swimming back to the ocean. Chinook salmon in the basin increased from an average of about two thousand to four thousand. Many of the Chinook were descendants of farmed fish, Pess told me over dinner in Nerka. “If ninety percent of your population before dam removal comes from a hatchery, you can’t just assume that an all-natural population will appear right away.” The rainbow trout, which had dwindled to a few hundred, now numbered more than two thousand.
Within a few years, a greater mix of local and wild farmed fish returned to the Elwha Basin. And the surrounding fauna responded too. The American dipper, a river bird, fed on salmon eggs and insects infused with new nutrients of marine origin. Their survival rates increased and females who had access to fish became healthier than those who did not. They began to have multiple offspring and did not have to travel as far for food, a return, perhaps, to what life was like before the dam. A study conducted in nearby British Columbia showed that the abundance and diversity of songbirds increased with the number of salmon. They didn’t eat the fish; in fact, they were not even present during the salmon migration. But they were benefiting from the increase in insects and other invertebrates.
Equally exciting was the fact that dam removal revived migration patterns that had lain dormant. The Pacific lamprey began traveling upstream to breed. The bull trout that had spent generations in the reservoir above the dam began to migrate offshore. Rainbow trout swam up and down the river for the first time in decades. As the years passed, the river began to look almost natural as sediment that had accumulated behind the dams was washed downstream.
Success at Elwha could be the start of something big, spurring the removal of other aging dams. There are plans to remove Enloe Dam, a fifty-foot-high concrete wall in northern Washington, which would open two hundred miles of river habitat for steelhead trout and Chinook salmon. Critically endangered orcas off the coast of the Pacific Northwest would benefit from this increase in salmon, and with only seventy individuals left, they need all the fish they can get.
Spring Chinook salmon flow on the Klamath River in Northern California has declined 98 percent since eight dams were built in the 20th century. Coho salmon have also seen a sharp decline. In the coming years, four dams are scheduled to be torn down with the goal of restoring salmon migration. Further north, Snake River dams could be breached to save Washington state’s endangered salmon. If that happens, historic numbers of salmon could return, along with many species that relied on the energy and nutrients they transported upstream.
Other dams are being built in the West: stick, stone and mud dams. Beaver dams help salmon by creating new slow-water habitats critical for juvenile salmon. In Washington, beaver ponds cool streams, making them more productive for salmon. In Alaska, the ponds are warmer and the salmon use them to help metabolize what they eat. Unlike huge concrete reservoirs, designed for stability, beaver dams are dynamic, heterogeneous landscapes that salmon can easily traverse. Beavers eat, build dams, defecate and move on. We humans may want things to be stable, but the Earth and its creatures are dynamic.
This article originally appeared on Engadget at https://www.engadget.com/hitting-the-books-eat-poop-die-joe-roman-hatchette-books-153032502.html?src=rss
