Application of Salish Sea model: water quality improvement through anthropogenic nutrient reductions

Salish Sea includes a network of coastal waterways spanning the southwest British Columbia (Canada) and northwest Washington State (USA) and includes the major waterbodies, the Strait of Georgia, the Strait of Juan de Fuca and Puget Sound. The Salish Sea Model was developed by PNNL in cooperation with Ecology based on the unstructured FVCOM model for hydrodynamics and the CE-QUAL-ICM model for water quality. The model is forced by river and wastewater inflows, tides, wind and solar radiation. The land based freshwater inputs include almost 100 wastewater plants (municipal and industrial) as well as another 100 or so watershed inflows that have direct discharge into the Salish Sea. These sources contribute anthropogenic loadings of nutrients to the Salish Sea. An assessment of the model’s response to reference conditions as well as current conditions gives us a sense of the extent of water quality impacts due to anthropogenic nutrient loads alone. An overview will be presented that will include model response from our latest model scenarios with various reductions of anthropogenic nutrient loads and how the model responds to these reductions. This will set the stage on how we may approach a “nutrient management strategy” to reduce/eliminate the impact of anthropogenic nutrient loads on dissolved oxygen