Tenasillahe Island Restoration Project
Multiple factors have contributed to the decline of anadromous salmonids throughout the Columbia River basin. The lower Columbia River and estuary are of particular importance because all stocks of anadromous salmonids within the basin use the area to varying extents, especially as rearing habitat for juveniles. Lower Columbia River habitats have been substantially altered by such factors as flow manipulation and dike construction.
The U.S. Army Corps of Engineers' (USACOE) has proposed a phased restoration project at Tenasillahe Island intended to benefit juvenile salmonids. Restoration actions may include tidegate modifications, construction of controlled water inlets to improve water movement and juvenile salmonid ingress and egress between the sloughs and river. Activities of the long-term phase may include breaching dikes on the island to restore tidal circulation to natural conditions.
The U.S. Fish and Wildlife Service, Columbia River Fisheries Program Office (CRFPO) is conducting pre-and post construction assessment of this restoration project. The goal of this assessment is to describe fish presence, distribution, habitat use, and accessibility as well as habitat characteristics of two sloughs at Tenasillahe Island and Welch Island, an adjacent un-diked island. Ultimately, comparisons will be conducted between sloughs on Tenasillahe Island (treatment site) before and after construction associated with the USACOE restoration project, and among sloughs on Welch Island (reference site).
This unique opportunity to conduct pre- and post-construction monitoring will assist in evaluating the overall effectiveness of the restoration project and will likely contribute to other potential restoration efforts in the Columbia River estuary.