Addressing sea-level rise in Boundary Bay, B.C. through a “Living Dike” approach

Boundary Bay, located in the greater Vancouver area on the west coast of British Columbia, is an important marine ecosystem that provides many ecosystem services to the surrounding communities of Surrey, Delta, White Rock and Semiahmoo First Nation. With 400 ha of salt marsh, the area provides habitat for many species, including juvenile salmon, and is recognized as an Important Bird Area of the Pacific Flyway. The Boundary Bay marsh also provides flood regulation, by reducing the level of wave energy that reaches the approximately 15 km of coastal dikes installed to protect the surrounding communities and regional infrastructure. However, it is projected that by 2100, the salt marsh may be completely inundated and lost due to coastal squeeze—the intertidal habitat loss that arises due to the high water mark being fixed by the dike and the low water mark migrating landwards in response to sea-level rise. To prevent this from happening, the City of Surrey, the City of Delta and the Semiahmoo First Nation are collaborating to find an innovative solution. The “Living Dike” concept, led by West Coast Environmental Law, seeks to elevate areas of the salt marsh habitat by gradually delivering salt marsh material, coupled with the recurring planting of salt marsh vegetation. By raising the marsh slowly over the course of 25 to 30 years, organisms will be able to adapt as they migrate southward, while the marsh continues to provide ecosystem services such as wave protection.

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