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Date Permissions Signed
Date of Award
Master of Science (MS)
Homann, Peter S., 1953-
Helfield, James M.
Matthews, Robin A., 1952-
Two large dams on the Elwha River, on the Olympic Peninsula in Washington State, are scheduled for removal in 2011. Removing the Glines Canyon Dam will release up to 10.6 million cubic meters of sediment from Lake Mills. The sediments will be exposed to new physical and chemical conditions and be redistributed throughout the ecosystem. In the summer of 2008, sediment samples were taken from the above-water delta and the submerged lake bottom of Lake Mills to identify initial physical and chemical characteristics relating to the variable status of phosphorus in the sediments. The sediments were analyzed for different forms of phosphorus (P), amorphous iron (Fe), carbon (C), nitrogen (N), and particle size. The lake sediments had greater concentrations of all elements analyzed and had smaller mean particle size compared to the delta sediments. A two-week incubation of sediments under various environmental conditions indicated P release was not affected by atmosphere type. For delta sediments, P release was greater in freshwater than saltwater throughout the incubation, while for lake sediments this occurred only initially. Overall, the magnitude of P release was similar for the two sediment types. An isotherm study performed in conjunction with the incubation study revealed that both the lake and delta sediments could immobilize large quantities of added P, but lake sediments maintained dissolved P concentrations at half the level of delta sediments. Managers could use the information found in this study to help understand the phosphorus release and immobilization patterns in sediments after dam removal.
Western Washington University
Elwha River (Wash.)
Copying of this thesis in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Cavaliere, Emily, "Elwha River sediments: phosphorus dynamics under diverse environmental conditions" (2010). WWU Graduate School Collection. 43.