Science, Uncertainties, and Limitations about Juvenile Salmon Habitat Restoration in the Lower Columbia River Gorge

The lower portion of the Columbia River Gorge (Lower Gorge) extends from Bonneville Dam downstream to the mouth of the Sandy River (RM 146 to RM 122). This dramatic portion of the Columbia River, which was formed during ice-age floods, is protected by the Columbia River Gorge National Scenic Area Act.  Tourism, recreation, transportation, and hydropower activities and associated infrastructure in the Lower Gorge are a key component of the region’s identity and are vital to its economy.

Historically, the majority of research and restoration efforts in the lower Columbia River focused on estuarine and urban portions of the river, neglecting the Lower Gorge. However, recent monitoring efforts that filled previous knowledge gaps indicate that floodplain and tributary habitats in the Lower Gorge likely are important not only to spawning populations of Lower Columbia River salmonids, but also to up-river stocks that rear in the estuary as they out-migrate towards the ocean.  This presentation will summarize the findings from these studies and others that illustrate the potential importance of juvenile salmon habitat in the Lower Gorge and opportunities for its restoration. Additionally, it will use case studies of current restoration projects to address key uncertainties (e.g., the historic importance of Lower Gorge habitats), limitations (e.g., transportation infrastructure), and positive attributes (e.g., high levels of protection afforded by strict land use regulations) associated with restoration of juvenile salmon habitat in the Lower Gorge.