Recent discussions around the proposed Roberts Bank Terminal at the mouth of the Fraser River and its potential transboundary effects outside of Canada are a reminder of the significance of the Fraser River for the entire Salish Sea.
This map shows the major rivers of the Salish Sea’s watersheds along with heavily generalized marine surface currents. The Salish Sea is considered an estuarine ecosystem due to the large amount of freshwater that enters the sea each year, and well over half of that freshwater comes from the Fraser River. This freshwater mixes with the marine waters that enter the Salish Sea from the Pacific Ocean to form a brackish surface layer. The brackish surface water currents spread out both north and south from the mouth of the Fraser River, eventually reaching much of the Salish Sea.
Ocean currents do not recognize international borders. Changes to the Fraser River therefore have the potential to alter ecological and oceanographic conditions across the Salish Sea.
You can learn more about the rivers and watersheds of the Salish Sea in the Freshwater chapter of the Salish Sea Atlas.
Map details: the rivers are symbolized by their average annual discharge of freshwater during the 1981-2010 time period, with data from USGS and Environment Canada (full data details and download available here). The Brackish Surface Flow currents are heavily simplified and generalized representations of the annual tidally averaged surface flow based primarily on Khangaonkar et al.’s (2016) analysis of results from the Salish Sea Model. Larger surface current arrows indicate larger volume currents. Download the full-size map here.