In 1998, the Washington State Department of Transportation (WSDOT) with funding assistance from the Federal Highway Administration, constructed a groin and underwater dike adjacent to State Route 105 on the north side of Willapa Bay in the vicinity of North Beach. The structure was designed to arrest the northward migration of a deep ebb tidal channel that, if continued to move northward, threatened to erode the only transportation link connecting Tokeland and the Shoalwater Indian Reservation with Grayland and Westport. The structure was built in two segments: an above-water portion, generally referred to as the groin, and an underwater portion, referred to as the dike. As a condition of the emergency construction authorization, WSDOT agreed to conduct a biological monitoring program to evaluate the effect of the structure on the habitat and migration habits of salmonids that pass through the estuary and coastal area on their way in or out of Willapa Bay. The WSDOT supported a habitat evaluation study conducted by scientists from spring 2001 through fall 2002. The study was carried out in three phases to determine the effects of the structure on juvenile salmon (June 2001 and May 2002) and returning adult salmon (October 2001). Reports of the 2001 field monitoring programs have been completed. This document provides a summary of these reports and the results of the May 2002 field survey.
Pacific Northwest National Laboratory (U.S.)
Animal migrations, Beaches, Behavior, Data collection, Dikes, Environmental impacts, Erosion control, Estuaries, Field studies, Fishes, Groins (Hydraulics), Habitat (Ecology), Monitoring, Salmon, Shore protection.