Lower Elwha River Restoration, Lower Elwha Klallam Tribe, WA
Dr. Abbe has been working in the Elwha River for 15 years where his engineered logjam (ELJ) work has been a crucial component of restoring the river’s lower 3 miles prior to and following dam removal of the Elwha and Glines Canyon Dams 2011 – 2013. NSD’s latest state-of-the art ELJ design introduced a new architecture that accommodates over a 90 degree change in the direction of incident flow while retaining the critical racked logs at the upstream face of the structure. The architecture also economizes the number of logs and uses the racked log piles to reduce the risk of scour compromising structural integrity. Dr. Abbe led a detailed geomorphic investigation to evaluate in-stream habitat and function of existing ELJ’s. In addition, a 2-dimensional hydraulic model was used to predict flow distribution following aggradation. The results of the geomorphic and hydraulic analyses were used to inform design architecture and layout of additional habitat structures to provide stable, long-term salmonid habitat. The NSD designs were developed specifically for the Elwha Tribe to implement with their own construction crew.