Nearshore Restoration | Elwha Watershed Information Resource

Removal of the Elwha and Glines Canyon Dams will only partially restore the severely degraded nearshore of the Elwha River. Once the dams are removed, 17 million cubic yards of sediment (for example, silt and sand) that have built up behind the dams over the last ninety years will be released into the river. Within five years, about half of that sediment will travel downriver into the nearshore area and the Strait of Juan de Fuca (Shaffer and others 2005). (The rest of the sediment will remain in the watershed.) However, this initial transport of sediment is only one step in the nearshore restoration process.

Lower Elwha Klallam Tribe seining in the east estuary.
Anne Shaffer, Washington Dept. of Fish and Wildlife

In order to restore the nearshore ecosystem, additional monitoring and restoration projects will need to be implemented. Restoration monitoring (such as sampling of fish habitats and modeling and mapping coarse sediments) can provide key information in aiding the recovery of the nearshore area. Monitoring and research can help identify additional restoration projects that may be needed. Generally, these projects are small, well-defined efforts--but taken all together they can have dramatic impacts on the restoration of the nearshore. However, it is important to realize that the nearshore will likely never be restored to its pre dam condition. And yet, it is possible to restore the health of the nearshore ecosystem by removing the dams and implementing key restoration projects. The Elwha nearshore area falls under multiple jurisdictions (local, city, county, state, tribal, and federal), so cooperation between jurisdictions is essential to restoring the nearshore. Restoration projects can be implemented at any jurisdictional level, but the projects will need to be designed in collaboration with the groups working on the restoration of the entire Elwha River Watershed.

However, before any restoration projects can be designed, it is essential to understand the current state of the nearshore and establish methods for monitoring the progress of the natural restoration after the dams are removed. The baseline record of the nearshore will give researchers something to compare post dam removal observations against. Researchers have already developed initial shoreline monitoring projects to define the current state of the nearshore (before the dams are removed). Historical baseline records and information about similar, healthy local ecosystems will be used to help set restoration goals. Below is a summary of the initial steps necessary to define the nearshore ecosystem response (Shaffer and others 2006).

Defining Elwha nearshore ecosystem response in four key steps:

Determine where the sediment will settle in the nearshore and how long it will take to get there;
Identify and describe historic habitat areas and use;
Identify and describe current habitat areas and use;
Refine future models of the nearshore using information from the previous steps.

It may take up to five years for the sediment to settle in the nearshore. Some of the sediment may actually be harmful to nearshore marine life and vegetation in the short term--for example, if oyster beds are smothered by sediment or if new sediment disrupts a spawning area. While some negative impacts are unavoidable, closely monitoring and assessing the natural nearshore restoration after the dams are removed gives researchers a chance to negate some of the harmful effects by implementing individual restoration projects in a timely manner.

Framework for Assessing Nearshore Restoration

Researchers from the Washington Department of Fish and Wildlife, Lower Elwha Klallam Tribe, Olympic National Park, NOAA Fisheries, and Clallam County developed a strategy for 1) monitoring the nearshore response to removal of the Elwha River dams and, 2) defining additional restoration needs associated with salmon recovery. This section highlights the framework presented in their full report. A conceptual model for defining nearshore restoration of the Elwha is presented in the Puget Sound Research Conference 2005 proceedings.

Two important components need to be addressed in order to understand the nearshore response. The first component looks at how the Elwha nearshore is changing (both positively and negatively) in the time period following the dam removal. But just looking at that component is not enough to show definitively that the dam removal is responsible for the change. Theoretically, the altered resource and habitat function could be due to changes in local climate, water quality, etc. To determine which changes in the Elwha nearshore are due to the dam removal, researchers will look at the second component. This component compares the Elwha nearshore to similar nearshore areas outside of the Elwha. If similar changes occur in both locations, the change may be due to something other than the dam removal.

Metrics will be used to quantify the changes that occur. Specific metrics to be considered include (taken directly from by Shaffer and others 2005):

Current fish use:

The current fish use within the Elwha and comparable nearshore.
The current habitat structure and function within the Elwha and comparable nearshore.
The current functional linkages between fish use and habitat structure within the nearshore of the Elwha and comparable sites.

Post dam removal fish use:

The short- and long-term nearshore use by targeted fish species post dam removal in the nearshore of the Elwha and comparable areas.
The short- and long-term nearshore habitat structure response to dam removal within the nearshore of the Elwha and comparable nearshore areas.

Once researchers collect the required information, observed trends will be compared against predicted trends to identify other areas that need additional restoration.

Future Efforts

The upcoming Elwha restoration event--that is, the removal of the two dams and the subsequent redistribution of the built-up sediment--provides a special opportunity. Not only will the event partially restore a significantly degraded nearshore, but it will also allow researchers to study the relationship between the restoration processes in the nearshore and the rest of the watershed (Shaffer and others 2005). Many research activities and restoration projects will be undertaken at this site to help assess and restore the nearshore area.

In order to optimize the natural nearshore restoration after the dams are removed, it is important to have a good understanding of the nearshore area (Shaffer and others 2006). On that front, there are still several tasks that need to be addressed to get a clear picture of the nearshore area and an idea of how it will respond once the dams are removed. The 2006 paper by Shaffer and others highlights these remaining tasks:

Extensive sampling of habitats and fish use in the nearshore area to get baseline information;
Historic mapping of the nearshore;
Final modeling of sediments; and
Addressing water quality and the fate of fine sediments in the Elwha River.

For more information on the latest activities and collaboration opportunities of the Elwha nearshore consortium, please visit the Nearshore Consortium page.

Reference

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.

Shaffer J. A.and others. 2005. "Elwha and Glines Canyon dam removals: nearshore restoration and salmon recovery of the central Strait of Juan de Fuca." Proceedings, Puget Sound Research Conference 2005, Puget Sound Water Quality Action Team, Olympia, Washington. Download.

Additional Information

Stolnack, S., and R. J. Naiman. 2005. Summary of Research and Education Activities in the Elwha River Watershed and Adjacent Coastal Zone. Download.