Restoring a habitat restoration at Deltaport East Causeway: lessons learned

Deltaport East Causeway is on the west shore of Fraser River Delta. In 2010, VFPA constructed habitat along the causeway as a condition of the Fisheries Act Authorization for Deltaport Third Berth Project. The original habitat... [ view full abstract ]

Deltaport East Causeway is on the west shore of Fraser River Delta. In 2010, VFPA constructed habitat along the causeway as a condition of the Fisheries Act Authorization for Deltaport Third Berth Project. The original habitat was monitored annually for both biological and physical metrics. Monitoring indicated that wave and wind exposure was preventing establishment or impairing functions of shoreline and habitat along the causeway. Performance deficiencies were related to salt marsh productivity and retention of beach sediment.  

In 2016 we proposed a remedial concept to address performance deficiencies relating to salt marsh productivity and retention of beach sediment. The barrier beach and back beach marsh concept made use of onsite materials, was both cost effective and efficient in creating and enhancing habitat for species that use the area. The design was developed with well-known geomorphological principles of crenulate beaches in terms of wave exposure, beach planform and sediment distribution based on several local natural analogs.  The beach combined with artificial headlands provides a dynamically stable framework on which to support diverse habitat even under conditions where sediment supply has been interrupted or does not exist due to local conditions. One year on, the beach and marsh has performed well morphodynamically.  Establishment of new salt marsh has encountered challenges, including:  accumulations of eelgrass wrack from adjacent sub-tidal flats and woody debris, and scour of back beach marshes during strong southeasterly winter storms.  This paper outlines, the design basis for beaches and marsh complexes, lessons learned and mitigation options moving forward.