Oxbow Park Stream Restoration Project, Portland Water Bureau, Portland, OR
Natural Systems Design and partners are currently working on an Engineered Log Jam design on the Sandy River that is intended to engage relic side channels to enhance aquatic habitat for overwintering juvenile coho. The project allows the Portland Water Bureau to meet its mitigation obligations established in the 2010 Bull Run habitat conservation plan (HCP). The proposed design increases side channel habitat and complexity while preserving a natural experience for the park’s many visitors. Site constraints include steep and limited site access, a very dynamic river morphology with significant peak flows, public safety, and aesthetic considerations. This project is based off of a larger geomorphic assessment that assessed ongoing geomorphic trends of this dynamic river that is highly influenced by eruptive events from Mount Hood. Significant lahars from the volcano effectively re-set the channel and floodplain, and a key finding of the geomorphic study is that the Sandy is still adjusting to recent mud flows, so enhancement designs not only need to look at current conditions, but need to account for the ongoing geomorphic trajectory of the river.