Early last December a rock slide occurred downstream from the Twin Bridges crossing of the Seymour River, partially blocking the channel and backing up the river.
A large area of the forest was flooded and many trees remain underwater.
The subsequent removal of the public footbridge was necessary because debris caught up on the submerged bridge deck and put the integrity of the structure at risk. The slide also created a permanent barrier to fish trying to migrate upstream, blocking access to salmon and steelhead.
In 2015 steelhead runs were damaged by the slide in January, and the salmon runs were hindered in the fall. Fisheries and Oceans Canada, the Seymour Salmonid Society, and the Squamish and Tsleil-Waututh First Nations operated a system of hoop nets to capture and transport fall-run salmon over the barrier into the upper river.
Ongoing fish trapping and a subsequent radio-tagging program is providing insight into the movement of fish in the lower river and could be of benefit if a longer-term trapping program is pursued.
While the limited trap and haul programs were successful in terms of saving brood stock for the hatchery this past season, it is not likely that this can be successfully sustained at times when the river flows are much higher, such as after a heavy rain or during the spring freshet.
Several engineering companies were recently engaged to assess how the barrier can be made more accessible for fish. They examined various options ranging from doing nothing to completely removing the slide debris with blasting and heavy construction. The recommended option is to re-shape the rock slide with scaling, and non-explosive, low-velocity rock breaking, and using the natural river flows to move material.
The project must work within specific fisheries windows and as such may span up to four years. This is due to two main factors: the safety of the fish and the use of natural river action to dissipate the debris. Once the required environmental approvals are obtained and funds have been raised, work will commence – which will hopefully be within the first available fisheries window.
The pedestrian bridge is located within the Lower Seymour Conservation Area, which is owned and managed by Metro Vancouver. An engineering firm is working on a conceptual plan for re-establishing pedestrian access across the Seymour River and improving access from Riverside Drive.
Metro Vancouver has committed to bring designs and plans to the public in April/May 2016 for input, with final detailed plans being completed within the year, and construction taking place in 2017. In 2016, they also plan to improve the Baden Powell staircase, which should facilitate the west to east connection across the Seymour River at the south end of the Lower Seymour Conservation Reserve.
I, along with the many frequent users of this trail network, am eager to see the natural fish runs return to the Seymour River, and the Twin Bridge crossing restored. Mother Nature is a powerful force and incidents such as the slide are reminders that we cannot plan for every circumstance. However, the excellent inter-agency cooperation across different levels of government, First Nations and the Seymour Salmonid Society is a testament to our community’s resiliency and the recovery we can achieve.
