The Role of Tie Channels in Restoring Pre-Development Geomorphic Conditions on the Lower Columbia River: A Case Study

Tie channels have only recently been identified as key landscape features on the world’s larger rivers. They typically occur within the freshwater tidal portion of river systems. With extensive modification of the greater Columbia River basin, these features have not been identified before because of its altered topography and hydrology. Identification of these features is discussed along with the limits of their presence on the lower Columbia River. It is likely that tie channels were common prior to European settlement in portions of the Lower Columbia River valley, and likely played a key role in the survival of many life stages of anadromous fish species, particularly salmon. Recovering these novel features on the lower Columbia River requires an understanding of their geomorphology and the physical processes leading to their creation. A case study, a tie channel at Scappoose Bay, is discussed to illustrate these geomorphologic and the physical processes.