Breaking new estuary ground on the Steveston Jetty

Restoration of the Fraser Estuary begins

Steveston Jetty on a grey day, with overset diagrams showing some of the work we're doing.

This week we break new ground…literally! Raincoast has now begun construction of three breaches of the Steveston Jetty. The Steveston Jetty is an 8 km long rock jetty which controls the position of the main arm of the Fraser River as it enters the estuary for the benefit of shipping. However, this restricts the movement of juvenile salmon. This project will greatly benefit juvenile salmon entering the estuary, just in time for this year’s juvenile out-migration season.

The Steveston North Jetty, as with a number of others on the south side of the main arm, were constructed beginning in the early 1900’s with the shipping in mind, and likely with little consideration for environmental impacts. The jetty is a significant barrier to the natural movement of the juvenile salmon entering the estuary, preventing them from moving into brackish marsh habitats on Sturgeon Bank and instead forcing them into the deeper and salty water of the Salish Sea. For juvenile Chinook, chum and pink salmon, which enter the estuary as fry, this lack of access to marsh habitats may be particularly harmful, and they may not have had time to prepare their bodies for the transition to salt water.

When we began our research in the Fraser estuary in 2016, the presence of multiple barriers, including the Steveston Jetty, became a significant concern. With the announcement of the Coastal Restoration Fund in 2017, an opportunity to begin addressing these barriers appeared. Applying to the fund was the first step, and after we found out that we had been successful the real work started, which brings us to this week.

With support from Fisheries and Oceans Canada, we began to study the potential impacts of creating new breaches in the jetty, to help identify both the potential benefits and any potential negative impacts to shipping and navigation in one of Canada’s busiest shipping areas. We retained the expertise of hydraulic modeling specialists to run different model scenarios of breach locations and sizes, with promising results which demonstrate not only the potential new movement pathways for salmon but also restoration of the natural movement of freshwater and fine sediments which support a healthy delta.

Once we knew the potential benefits were high and the potential risk small, we retained engineers to draft a design, and began working towards the necessary permits and approvals. Long story short, everything has fallen into place just in time to meet our goal of completing phase 1 construction prior to the beginning of the 2019 juvenile salmon outmigration and spring freshet period. Phase 1 will remove rock from the jetty in three locations, creating 50 meter wide breaches. Once the rock is removed we will monitor the development of channels on Sturgeon Bank, along with changes to salinity and marsh vegetation. We will also monitor changes in juvenile salmon use of the surrounding marsh, comparing with baseline data collected in 2018.

If all goes according to plan, phase 2 construction will occur after a year of monitoring, and will further reduce the depth of the breaches so they are available at all but the lowest tide heights, creating multiple new ways for juvenile salmon, freshwater and sediment to move through the estuary in a more natural manner, hopefully resulting in direct benefits to juvenile salmon growth and survival.

This project is just one part of Raincoast’s five year Fraser Connectivity Project. We hope to build a series of projects which restore migration pathways for juvenile salmon throughout the Fraser estuary, while conducting extensive baseline and effectiveness monitoring to measure the impact of our restoration activities. Stay tuned for more updates.

For the Fraser and its salmon.

David Scott, Raincoast Lower Fraser Salmon Program Coordinator A squinting David Scott explains about the Fraser River

David Scott is interested in resource and environmental management, ecology and conservation of aquatic ecosystems. He’s working in the Fraser river and doing a PhD at the University of British Columbia. You can find David in the wild, looking for salmon.

 

Fraser River Estuary Project

 

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