Preliminary impacts of the Elwha Dam removal project to primary productivity

Abstract

Dam removal on the Elwha River has increased sediment concentrations in the buoyant river plume emptying into the Strait of Juan de Fuca. Such increased turbidity can decrease light available for primary production in the water column and may negatively impact primary production, which could have bottom-up effects on the entire food chain. To investigate the effects of turbidity, sediment profiles, light profiles, and chlorophyll-a profiles from the delta were analyzed for both in-plume and out-of-plume stations. Differences in sediment concentration and light attenuation occurred between stations within and without of the plume, and trends suggest that mixing in the water column may enhance primary production within the plume.