Port proposes building marsh at mouth of river
Creation of wildlife habitat would offset damage done by development
The Vancouver Fraser Port Authority is proposing to convert a sand flat at the mouth of the Fraser River into 43 hectares of productive, intertidal marshland for wildlife, including juvenile salmon and birds.
The initiative, which the province says doesn’t require a formal environmental assessment, is designed to offset environmental damage associated with ongoing port development, including a planned container expansion at Roberts Bank.
The marsh would be located immediately north of Steveston’s south arm jetty, next to the 5,152-hectare provincial Sturgeon Bank Wildlife Management Area. The port is proposing to initially build up the sand flat with fill. After the fill settles, marsh vegetation tolerant of brackish water would be planted or allowed to colonize naturally.
Environment Canada biologist Sean Boyd said in an interview that the port’s proposal “could be positive, developing some productive marsh habitat, if engineered properly.”
His main wish is that the project be located and/or designed so that fresh water from the Fraser River can flood into Sturgeon Bank — prime wildlife habitat that’s suffering from erosion. The new habitat would also have to be protected with rip-rap rock to prevent damage from currents and storm waves, he noted.
Research shows that some areas of Sturgeon Bank have receded by up to 500 metres over more than two decades.
One theory is that the jetty has funnelled fresh water out into the Strait of Georgia, thereby causing a die-off of plants such as three-square bulrush as salinity levels have increased in Sturgeon Bank. To the south, these plants thrive at Westham Island, which receives more fresh water from the Fraser.
Federal and provincial officials are working together on the dilemma, since the implications are serious for birds, young fish and people.
Loss of the marshes would allow rising sea levels to hammer away at exposed municipal dikes.
Boyd said that climate change has also altered the timing of the spring freshet of the Fraser — lower and earlier peak flows, which may get worse in the future.
Sediment flows are also part of the picture.
“It’s becoming fairly complex,” Boyd said.
“All of these things seem to be affecting each other.”
The Fraser River estuary is an important migratory, rearing and spawning area for fish, juvenile salmon, as well as serving as a globally recognized bird habitat, including a stopover for western sandpipers headed north to breed in spring.
A port overview of the planned project submitted to the environmental assessment office in Victoria notes that, in the late 1970s, about 44,000 cubic metres of sand and silt were dredged from the lower Fraser River and placed on Sturgeon Bank for an experimental marsh project.
The project didn’t include an adequate buffer to protect the site from wave action and the fill material eventually dispersed.