Event Title

Sediment loads along Puget Sound rivers: Implications for ecosystem health

Presentation Abstract

Washington State rivers carry about 6 million tonnes of inorganic sediment to Puget Sound each year. This load of gravels, sands, and fines provides beneficial material to river channels, floodplains, deltas, and sea beds. However, sediment can also detrimentally affect ecosystems in the greater Puget Sound watershed. For example, the Puyallup River network, which drains glaciated Mount Rainier volcano, carries about 1 million tonnes of sediment to Puget Sound each year while supporting important runs of steelhead, Chinook, coho, and pink salmon. Significant 20th century river management and development in the floodplain reduced aquatic habitat available to salmon. Acute sedimentation in certain river reaches, coupled with endangered species issues, now creates challenges for flood-risk management professionals tasked with protecting both the Puyallup River ecosystem and people and industries within the floodplain. Recent USGS research identified reaches of aggradation, sources of sediment, and temporal patterns of sediment delivery. Though the Puyallup River carries most of its sediment load during winter floods, significant sediment loads also occur during warm summer days when snowmelt or glacier melt produce pronounced spikes in suspended-sediment concentration. Similar sediment-monitoring and geomorphic research in the Elwha River is illustrating river response for river conditions of extreme surplus sediment. Comparative analysis of the Puyallup and Elwha Rivers enable insight into geomorphic response to heavy sediment loads of Pacific Northwest mountainous rivers. Throughout Puget Sound, improved understanding of the temporal and spatial dynamics of fluvial sediment will foster better strategies to manage sediment and impacts to ecosystems and people.

Session Title

Session S-03G: Ecosystem Services and Impacts of Sediment for Salish Sea Recovery

Conference Track

Shorelines

Conference Name

Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)

Document Type

Event

Start Date

30-4-2014 3:30 PM

End Date

30-4-2014 5:00 PM

Location

Room 6E

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

Text

Language

English

Format

application/pdf

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Apr 30th, 3:30 PM Apr 30th, 5:00 PM

Sediment loads along Puget Sound rivers: Implications for ecosystem health

Room 6E

Washington State rivers carry about 6 million tonnes of inorganic sediment to Puget Sound each year. This load of gravels, sands, and fines provides beneficial material to river channels, floodplains, deltas, and sea beds. However, sediment can also detrimentally affect ecosystems in the greater Puget Sound watershed. For example, the Puyallup River network, which drains glaciated Mount Rainier volcano, carries about 1 million tonnes of sediment to Puget Sound each year while supporting important runs of steelhead, Chinook, coho, and pink salmon. Significant 20th century river management and development in the floodplain reduced aquatic habitat available to salmon. Acute sedimentation in certain river reaches, coupled with endangered species issues, now creates challenges for flood-risk management professionals tasked with protecting both the Puyallup River ecosystem and people and industries within the floodplain. Recent USGS research identified reaches of aggradation, sources of sediment, and temporal patterns of sediment delivery. Though the Puyallup River carries most of its sediment load during winter floods, significant sediment loads also occur during warm summer days when snowmelt or glacier melt produce pronounced spikes in suspended-sediment concentration. Similar sediment-monitoring and geomorphic research in the Elwha River is illustrating river response for river conditions of extreme surplus sediment. Comparative analysis of the Puyallup and Elwha Rivers enable insight into geomorphic response to heavy sediment loads of Pacific Northwest mountainous rivers. Throughout Puget Sound, improved understanding of the temporal and spatial dynamics of fluvial sediment will foster better strategies to manage sediment and impacts to ecosystems and people.