The Marmot Dam's concrete face was blown up in July 2007, liberating the Sandy River for the first time in nearly a century.
The fate of the Sandy River and its wild fish turned in what seemed like a moment, 10 years ago this October 19, as the river itself cleared away the last remnants of the Marmot Dam.
Undamming the Sandy liberated the entire 56-mile length of the river to flow freely for the first time in nearly a century. Dam removal also launched a watershed-scale conservation campaign to restore threatened wild salmon and steelhead -- which is beginning to bear fruit.
Two and a half salmon generations into its renewed life, the Sandy has shown us the resiliency of wild rivers and the potential of science-driven, community-based collaboration.
Doing what had never been done before
The 47-foot-high Marmot Dam blocked wild fish passage.
In 2007, removing a dam of this size – 47 feet high and 350 feet wide -- was unprecedented in the Pacific Northwest. Little was known about how to do it, and no one had ever de-licensed a federally licensed dam before. Only a confluence of circumstances, and years of extensive public-private cooperation, would lead to successful removal of Marmot, and the related Little Sandy Dam a year later.
Imagine it’s 1998: The water level in the Sandy River behind the 47-foot dam is only knee deep because the reservoir has filled with volcanic sediment from headwater glaciers on Mt. Hood. Adult salmon jump against the dam constantly from June through September attempting to migrate upstream to spawn. Returning wild salmon numbers have sunk catastrophically low throughout the Columbia Basin.
Beginning that same year, concerned Tribes, community advocates and scientists secured threatened listings under the Endangered Species Act to protect salmon in the Columbia Basin, including wild fish in the Sandy. Around the same time, the license to operate Marmot dam came up for renewal. To renew the license, Portland General Electric (the dam’s owner), would need to build improved passage for salmon and steelhead. The cost of meeting fish passage standards would have greatly exceeded profits generated from operating the dam. Given these circumstances, dam removal emerged as a clear win-win for PGE customers, fish and the Sandy, provided it caused no long-term harm.
The Sandy liberates itself for the first time in nearly a century.
The challenge remained: how to do what had never been done before at such a large-scale -- safely.
PGE and a team of stakeholders, collectively known as the “Sandy River Basin Partners,” and others came together and pooled resources to take advantage of this groundbreaking research opportunity. Scientists modeled the sediment load and flow rates in an experimental flume and decided one good storm could do the work of transporting the sediment away. This process became known as “Blow and Go.”
With great fanfare in July 2007, PGE CEO Peggy Fowler pushed the plunger that blew up the dam’s concrete face. Throughout the summer, workers peeled away the earthen structure, with a temporary earthen cofferdam holding the river back just upstream. The team waited for a storm with a high enough flow to transport the sediment downstream.
The storm struck October 19, 2007. With autumn rain pelting down, an excavator cut a small notch in the top of the cofferdam. He had barely made it safely to shore before the trickle became a stream, then quickly grew to a raging torrent. Within 19 hours, the Sandy roared back to life, carrying away decades of accumulated sediment overnight.
To see the demolition process of the dam, watch this time-lapse video.
Scientists were amazed to see how quickly the river righted itself and recovered its natural channel. Researcher Gordon Grant described the process as taking “one of the biggest unknowns in river geomorphology” and proving how the Sandy, “a large, energetic river, digests a mammoth meal of sediment.”
The primary goal of fish passage was achieved, as well as other victories. Despite fears, the water ran clear within days. The redistribution of sediment not only caused no harm, but also improved spawning habitat with the redistribution of gravels. Areas that had built up in the initial dam release eventually eroded back to pre-dam levels. No increased flooding occurred.
The Sandy 'digests a mammoth meal of sediment' shortly after dam removal.
For the health of the Sandy, dam removal was pivotal, but only the first leap toward recovery. Once it became clear in 1999 that the Sandy would eventually flow free, the Sandy River Basin Partners launched into action. The Partners restored miles of floodplain and side channel habitat. Work in key stream segments placed large logjams to give salmon places to spawn, feed, grow and migrate, jump-starting natural processes interrupted by historic development, logging, and post-flood clearing. Work along the stream banks in restoration zones reduced the spread of invasives and planted thousands of trees and shrubs for riparian vegetation.
Fellowship of the undammed
A decade later, the collaborative restoration of the Sandy is emerging as a success story in combining dam removal and science-based restoration to recover a river’s resiliency. Spring Chinook and Coho salmon and steelhead populations have shown significant growth, although fall Chinook appear to still be struggling. Monitoring shows increased spawning and juvenile rearing activity in restored areas. Wild fish remain threatened, but for those in the Sandy, the trajectory appears to have turned that rainy day in October.
The Sandy River Basin Watershed Council and partners are compiling a State of the Sandy, reviewing restoration that has been completed, how fish are responding, and how human population and activities have changed at basin and sub-basin scales. We’re examining what has worked, and how to further bolster and secure habitat gains.
The undammed Sandy is now a free-flowing corridor for fish, wildlife, and people.
Once a pioneer in the fellowship of the undammed, the recovering Sandy finds itself in good company. Over 1,000 dam removals have occurred nationwide in the last 40 years, and a recent USGS study indicated that many rivers return to their pre-dammed state quickly. Given a chance, river ecology can rebound. Salmon and other migratory fish can move back in. The Sandy’s lessons have also helped inform other dam removals, with sediment data shared in the planning for Elwha and other large-scale restorations since.
Post-dam progress in the Sandy has happened largely through voluntary collaboration. Hundreds of residents, dozens of agencies from local to federal, and thousands of volunteers of all ages have helped put habitat back together from Timberline to Troutdale. Challenges remain, from climate change, to continued development, to expanded impact from our year-round love of all kinds of recreation throughout the Sandy. Restoration of a century’s impacts will take more than one decade.
But for now, the Sandy offers a tale of ecological and social redemption: how dam removal and prioritized, collaborative, on-the-ground restoration have begun to restore the Sandy’s wild fish populations from deep decline to potentially historic recovery.
What seemed permanent proved to be a reversible step in river health.
Join the Sandy River Basin Watershed Council in celebrating 10 years of a free-flowing Sandy in conjunction with our 20th anniversary on Thursday, Oct. 19, from 6 to 9 p.m. at the Riverview Restaurant in Troutdale. Thanks to the PGE Habitat Fund, Metro, and Port of Portland for making this event possible. Tickets are only $25 and are available here.
The following organizations were either party to the dam removal process or are members of the Sandy River Basin Partners, or both. Many are also Intertwine Alliance Partners.
Alder Creek Kayak Supply, Inc.
American Rivers
American Whitewater
City of Sandy, Oregon
Clackamas County
Columbia Land Trust
East Multnomah Soil and Water Conservation District
The Freshwater Trust
Metro
Multnomah County
The Nature Conservancy
National Marine Fisheries Service
Native Fish Society
Northwest Sportfishing Industry Assoc.
Northwest Steelheaders
Oregon Council of Trout Unlimited
Oregon Dept. of Environmental Quality
Oregon Dept. of Fish and Wildlife
Oregon Dept. of State Lands
Oregon Trout Assoc.
Oregon Water Resources Dept.
Portland Water Bureau
Sandy River Basin Watershed Council
State of Oregon
Trout Unlimited Assoc.
U.S. Bureau of Land Management
U.S. Fish & Wildlife Service
U.S. Forest Service
WaterWatch of Oregon
Western Rivers Conservancy
SOURCES
https://www.usgs.gov/news/dam-removal-study-reveals-river-resiliency
http://onlinelibrary.wiley.com/doi/10.1002/2017WR020457/full
http://www.solutions-site.org/node/271