Elwha Watershed Information Resource

Strait of Juan de Fuca --estuary habitat with bull kelp. Betsy Carlson, National Park Service

The Elwha nearshore encompasses the area that extends from the treeline on shore out 90 feet (30 meters) to the average height of low tidal events. The primary Elwha nearshore includes a 13-mile stretch of shoreline in the central Strait of Juan de Fuca and the aquatic environment of the nearshore is estuarine/marine (that is, saltwater or a mixture of salt and freshwater).

The nearshore area is built up by the process of sedimentation, the natural method whereby minerals and organic matter (such as silt and rocks) are deposited along the Elwha River nearshore region. Since the early 1900s, the natural flow of sediment down the river has been blocked by the Elwha and Glines Canyon Dams (constructed in 1914 and 1927, respectively). This sediment starvation has significantly reduced nearshore habitat and has negatively affected the species that use the nearshore (such as juvenile salmon). When the dams are removed, the natural flow of sedimentation will be re-established, but additional restoration projects will also be needed to restore the nearshore ecosystem.

Shoreline monitoring before and after the dams are removed is critical to understanding how the nearshore community structure will respond to the physical processes related to dam removal. For instance, a little over 17 million cubic yards of large and fine grained sediment have built up behind the two dams (NPS 1996). A significant amount of this sediment will be released into the river when the dams are removed, which initially may harm marine life (such as kelp, crabs, clams, and rockfish). Sediment releases will alter the nearshore substrate bottom from rocky to a mixture of sediment, which will change the habitat of plants and animals.

Four key steps have been developed by researchers to define the Elwha nearshore ecosystem response (Shaffer and others 2006):

• Define the geographic and temporal fate of the sediment once in the nearshore;
• Define historic habitat conditions and resource distribution;
• Define current habitat distribution and resource use; and
• Use the information from the first three to model future conditions.

These four steps are guiding pre dam removal research projects in the Elwha. One example of the many nearshore research projects is discussed in the section below. For information on all nearshore research projects, please see the Nearshore Consortium page.

Nearshore Fish of the Strait of Juan de Fuca--Implications for removal of Elwha Dams

Study Overview: This project involves studying nearshore fish communities. Information collected during this study will provide a baseline to track the effects of dam removal on the distribution and abundance of nearshore fish communities and aid in future dam removal assessments.

Research Activities: Since 2006, collaborators have been collecting data on nearshore fish communities at sites in the eastern and central Strait of Juan de Fuca from Discovery Bay to Crescent Bay. Between April and September (2006), sites were sampled on a monthly basis--as weather and tides permitted--using a 32-meter Puget Sound beach seine (net). Overall, 36 species were identified, including:

• Four species of Pacific salmon (Oncorhynchus species)
• Steelhead (Oncorhynchus mykiss), and
• Cutthroat trout (Oncorhynchus clarki).

Researchers found wide distribution of several fish species, including juvenile ling cod (Ophiodon elongatus) and all life stages of surf smelt (Hypomesus pretiosus). Pink salmon Oncorhynchus gorbuscha) were the most abundant of the salmon species.

Collaborators:

• Josh Chamberlin, NOAA Northwest Fisheries Science Center
• Jeff Duda, United States Geological Survey
• Kurt Fresh, NOAA Northwest Fisheries Science Center
• Anna Kagley, NOAA Northwest Fisheries Science Center
• Kim Larsen, United States Geological Survey
• Mindy Rowse, NOAA Northwest Fisheries Science Center
• Nikki Sather, Oregon State University
• Ann Shaffer, Washington Department of Fish and Wildlife
• Larry Ward, Lower Elwha Klallam Tribe

Notes

1. Nearshore Restoration of the Elwha River Through Removal of the Elwha and Glines Canyon Dams: An Overview
2. Observations of Eulachon, Thaleichthys pacificus, in the Elwha River, Olympic Peninsula Washington
   

Reference

National Park Service. 1996. Elwha River Ecosystem Restoration, Draft Environmental Impact Statement. National Park Service, Olympic National Park, 600 East Park Avenue, Port Angeles, Washington, 98362.

Shaffer, J. A. and others. Nearshore of the Central Strait of Juan de Fuca and Removal of the Elwha and Glines Canyon Dams: An Overview. March 2006. Download.