The largest dam removal project in U.S. history was conducted from September, 2011 to August, 2014 on the Elwha River in northwest Washington State. (Check out the Elwha River Restoration Blog by the National Park Service for more information about this exciting restoration project.) Our group is studying the fate of mud released from the former reservoirs to the coastal ocean. This system is providing excellent opportunities to study tidally dominated dispersal of fine-grained sediments, which has implications for signatures of natural and anthropogenic events like landslides, river floods, and dam removal in energetic coastal environments. Between 2011 and 2015, we deployed large bottom-boundary layer sensor platforms and collected grab samples, CTD/OBS casts, and water samples to study the dispersal and short-term deposition patterns of mud delivered by the river.
Jenny investigates a recently recovered tripod (Photo Credit: E. Eidam)
Light monitoring platform (Photo credit: I. Miller)
From 2015-2018, we are transitioning into a study focused on evolution of nearshore muddy deposits and the impact of fine-grained sediment on benthic communities. During dam removal ~10 Mt of sediment washed downriver, and previously abundant kelp virtually disappeared from the adjacent nearshore ecosystem. These kelp provide important habitat for ecologically important species such as salmon. The link between current benthic light availability and sediment delivery and transport was investigated in order to understand conditions during dam removal. Seven instrument platforms were been deployed for two-week periods to monitor were deployed on the 10-m isobath along a 16 km transect centered on the river mouth for seven fortnightly periods in 2016 and 2017 to monitor near-bed photosynthetically available radiation (PAR), suspended sediment, wave climate, current velocity, temperature, and salinity. Read more about the project on the Washington Sea Grant website.
And, check out this interactive website for video footage of dive surveys around the Elwha. This website is also part of an interactive display at the Feiro Marine Life Center.
Funding source: National Science Foundation, Washington Sea Grant
People: Andrea Ogston, Chuck Nittrouer, Ian Miller (WA Sea Grant), Emily Eidam, Kristen Lee Webster, Hannah Glover
Collaborators: Jon Warrick (USGS), Steve Rubin (USGS), Helen Berry (DNR)
Project publications
Eidam, E.F., Ogston, A.S., Nittrouer, C.A., Warrick, J.A. 2016. Tidally dominated sediment dispersal offshore of a small mountainous river. Continental Shelf Research, 116, 136-148.
Miller, I.M., Ogston, A., Dolan, J., 2015. Sedimentology of intertidal sediment deposits after dam removal on a coastal river. Coastal Sediments 2015, San Diego.
Gelfenbaum, G. Stevens, A.W., Miller, I., Warrick, J.A., Ogston, A.S., Eidam, E., 2015. Large-scale dam removal on the Elwha River, Washington, USA: Coastal Geomorphic Change. Geomorphology, 246, 649–668.
Data collected: 2011 – 2015
Time-series data were collected using a variety of acoustic, optical, and peripheral sensors mounted on two bottom-boundary-layer tripods. Each tripod measured ~2 m tall to allow for investigations of sediment transport processes within the boundary layer. Details of each tripod deployment including major sensors deployed are given below; data are available upon request to PI Andrea Ogston (ogston [at] ocean.washington.edu). Measurements were collected at hourly intervals for up to 6 minutes at frequencies ranging from 1-16 Hz.
Primary instrumented tripod
Secondary instrumented tripod
Data collected: 2016 – 2017
Time series data were collected following the methodology from the NSF program, with the same tripod. The tripod was deployed in two locations (see map). Light monitoring platforms were deployed at 7 locations along the 10-meter isobath. Bed sediment samples were collected across the delta using a shipek and a box corer. Water column profiles and water samples were collected during tripod and instrument platform deployments and recoveries.
Map of the Elwha River with tripod locations (triangles), light mount locations (circles), and bed samples (grey hexagons).
BBL Tripod
Light monitoring platforms
NOTE: Full time-series records are not available for all instruments for all deployments due to memory, battery, and/or biofouling issues.
Data is available upon request.
News & public presentations
Seeing the light at the Elwha Delta (May 2016)
Sediment flow at Elwha River’s mouth an outdoor classroom for University of Washington students (Peninsula Daily News, Apr 2015)
2015 Whiteley Lecture Series: mysteries of NW marine world explored (Feb 2015)
A unique lab class: UW students explore nation’s largest dam removal (UW News, Aug 2014)
Elwha dam removal creates outdoor classroom for U. Wash. students (Environmental Monitor, Aug 2014)
Dramatic changes following Elwha Dam removal (Kitsap Sun, Mar 2013)
Tracking sediments’ fate in largest-ever dam removal (UW Today, Mar 2013)
Researchers excited by early signs of Elwha changes (Peninsula Daily News, Jul 2012)
Related blog entries
Marine Sedimentary Processes Apprentices in the field (Oct 2018)
Elwha River research enters a new phase (Dec 2017)
Ocean 492, Autumn 2016 (Oct 2016)
Taking advantage of this rainy winter at the Elwha (Dec 2015)
CB1021 — another successful Elwha cruise! (Aug 2014)
Salish Sea Conference (May 2014)
Short Takes on Dam(n) Science (Feb 2014)
Rapid response cruise to the Elwha (Jan 2014)
Summer and fall Elwha cruises (Aug, Nov 2013)
Undergraduate Research Apprenticeship at Friday Harbor Labs (Spring 2014)
Elwha cruise with the Ocean 492 class (Apr 2013)
Ocean 492 at Friday Harbor (Spring 2013)
Elwha Science + Comics Interview (Mar 2013)
Recovering the Elwha tripod (and some surprises from the seafloor) (Mar 2013)
Elwha Nearshore Consortium Meeting (Feb 2013)
R/V Thompson cruise (Jan 2013)
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- Dave and Andrea get ready for sampling on the R/V Weelander
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- Ian Miller (WA Sea Grant) deploys a LISST in the Elwha surface plume
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- With the help of D. Thoreson from UW Oceanography, we prepare to deploy a mini instrument system.
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- The Barnes, ready to go at the Port Angeles Boat Haven dock
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- CTD sampling on a calm morning in Freshwater Bay
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- Retrieving a box core
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- The primary instrument seabed, fresh from the seafloor!
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- Sunrise at Port Angeles
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- Students help collect shipek grab samples aboard the R/V Barnes at the Elwha
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- Maggie, from UW CEE, helps prep sensors in advance of the next instrument deployment
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- An instrumented tripod ready to be deployed from the deck of the R/V Barnes in Port Angeles
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- Ocean 492 class, Spring 2014; field trip to former Lake Mills, Elwha River
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- Rocks (the pre-dam-removal substrate) mixed with freshly delivered reservoir mud
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- The Elwha plume intersects waters of the Strait on a cloudy fall day
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- Andrea & Aaron monitor the progress of the sidescan sonar system
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- At the end of the August cruise, the secondary tripod was returned to its 22-m site offshore of the river mouth
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- Dan and Niall work on both tripods at the Port Angeles harbor in August
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- New muddy/sandy deposits near the river mouth
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- Niall and Suzan set the Shipek to collect a seabed sample
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- Many portions of the subaqueous sample are still too coarse to sample with the Shipek. That doesn’t mean they always come back empty, though…
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- Kevin and Wenhua collect surface water samples in November
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- We caught barnacle season during the summer deployment. Lots of scrubbing happened immediately after this photos as taken.
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- MUD! (and sand) Finally seeing noticeable amounts of mud mixed with sand near the river mouth.
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- Riane collects light measurements from 1 m, 2 m, 5 m, and 10 m water depths in the surface plume.
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- Ben and Tianna collect water samples.
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- Andrea and Trevor prepare to collect a surface water sample with a Niskin bottle.
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- The primary tripod, ready for re-deployment at the Elwha
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- We recovered the tripod using the secondary acoustic release. The line for the primary release was a bit tangled. Above, Dan works to unlink the shackle from the retrieval line.
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- Back row, left to right: Riane, Brianna, Tianna, Trevor, and Campbell Front row, left to right: Kevin, Emily, Ben, and Andrea
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- The class explores lime deposits that were once mined from the island