In fall of 2011, the National Park Service began an incredible restoration experiment to remove the Elwha River dams.
A hundred years ago, anglo entrepreneur Thomas Aldwell looked at the narrow gorges of the Elwha River on the Olympic Peninsula and saw an opportunity. Within the span of a few decades, two dams were built along the river to generate hydroelectricity- the Elwha Dam, built about 5 miles upriver from the mouth in 1910 to power a pulp mill in Port Angeles, and Glines Canyon Dam, built another 8 miles upriver and completed in 1927 to supplement power to the growing City of Port Angeles and its industrial needs.
The dams had profound impacts on the Elwha River system, creating two major reservoirs, blocking anadromous fish passage to over 70 miles of spawning habitat, and starving the lower river of sediment while creating billions of cubic yards of sediment storage within the reservoirs themselves. By the 1980s, we started critically looking at these impacts questioning the need for these dams, which produced very little power relative to the needs of Port Angeles, and were now located within a National Park. In the early 1990s, congress passed the Elwha River Ecosystem and Fisheries Restoration Act, which set the stage for the dams’ decommissioning and removal.
In 2011, The Park Service and its partners began the restoration process removal of the lower dam, the Elwha River Dam, followed by the demolition of the dam upstream, Glines Canyon. Between the two reservoirs, 24 million cubic feet of sediment had built up- enough to cover Manhattan’s Central Park with 18 feet of material! Because there has been so much sediment built up in these rivers, the restoration had to be strategic in approaching its release- timing of removal had to be staggered and paced, to avoid periods of fish migration, and also to gradually move the depositional area of sediment in the upper reaches of the reservoir, allowing the river to move the sediments out. The Park Service has prepared a series of excellent web videos that show more detail about the history of the dams, and the process of their removal.
How is this related to climate change, you may well ask? As we know, our glacial systems are experiencing profound changes. Olympic national park is no exception- its glaciers are showing significant retreat, and with this retreat comes a host of changes to the park and its river systems: reduction in timing and magnitude of glacial-fed water supply, instability of its stream beds associated with glacial retreat, and shifts in the location and size of snow and snowmelt-dependent habitats. On our current trajectory, scientists predict essentially no snowmelt-dominant watersheds remaining in Washington by the end of the 21st century. These changes are profound. For the natural systems of the park and its wildlife, therefore, maximizing the function and integrity of the river systems that we do have becomes even more critical, because fish and wildlife facing the stressors of climate change are going to need all the help they can get.
Which brings me to why I spent a day with some friends and National Park Service staff planting seedlings along the windswept 20-foot-high sediment terraces that are the leavings of Mills Lake behind Glines Canyon Dam.In order to accelerate the revegetation and stabilization of the massive sediment terraces left behind from draining the reservoir, the Park Service has been conducting revegetation of the terraces. The effort is a massive one- 400,000 native plants are slated for replanting these denuded areas left behind by a hundred years of submergence- yet when you stand on the terraces, you feel absolutely dwarfed by their scale and wonder how many millions of plants, really, it will eventually take to bring this area back to a forested state. Especially since these little plants have a heck of a trial in front of them, working to recreate a soil system and plant community in river sediments that are currently almost devoid of organic material. One of the interesting things about our planting plots we worked on the day I went out was that some of our plants had been inoculated with mycorrhizae, a fungus that is symbiotic to plant roots and helps to fix nitrogen, thereby supplementing the plant’s nutrition; this was part of a study to evaluate whether mycorrhizal inoculation might assist with the survival and establishment of these new plantings.
We – collectively, there were about a dozen of us out there the day I went- probably got a few hundred plants in the ground. It feels like a drop in the bucket of several hundred thousand that are needed. But it is something. And it was profoundly moving to be able to bear witness to a major, major shift in the Elwha River ecosystem, from a dammed and suffering river, to one flowing free and offering passage to millions of salmon to its upper reaches once again. Because our rivers are going to need all the help they can get.