Rapid water quality change in the Elwha River estuary complex during dam removal

Limnology and Oceanography
By: , and 

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Abstract

Dam removal in the United States is increasing as a result of structural concerns, sedimentation of reservoirs, and declining riverine ecosystem conditions. The removal of the 32 m Elwha and 64 m Glines Canyon dams from the Elwha River in Washington, U.S.A., was the largest dam removal project in North American history. During the 3 yr of dam removal—from September 2011 to August 2014—more than ten million cubic meters of sediment was eroded from the former reservoirs, transported downstream, and deposited throughout the lower river, river delta, and nearshore waters of the Strait of Juan de Fuca. Water quality data collected in the estuary complex at the mouth of the Elwha River document how conditions in the estuary changed as a result of sediment deposition over the 3 yr the dams were removed. Rapid and large-scale changes in estuary conditions—including salinity, depth, and turbidity—occurred 1 yr into the dam removal process. Tidal propagation into the estuary ceased following a large sediment deposition event that began in October 2013, resulting in decreased salinity, and increased depth and turbidity in the estuary complex. These changes have persisted in the system through dam removal, significantly altering the structure and functioning of the Elwha River estuary ecosystem.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Rapid water quality change in the Elwha River estuary complex during dam removal
Series title Limnology and Oceanography
DOI 10.1002/lno.10129
Volume 60
Issue 5
Year Published 2015
Language English
Publisher Wiley
Contributing office(s) Pacific Coastal and Marine Science Center
Description 14 p.
First page 1719
Last page 1732
Country United States
State Washington
Other Geospatial Elwha River
Online Only (Y/N) N
Additional Online Files (Y/N) N