Volunteers with the Cougar Creek Streamkeepers and workers from the City of Delta have installed a beaver pond leveller to help minimize trail flooding along Lower Cougar Creek in the Delta Nature Reserve.
Park users may have noticed the leveller, which consists of a long flexible pipe through the beaver dam with a cage at the upstream end to prevent beavers from blocking the pipe intake, alongside the main trail between the second and third boardwalk entrances.
The level of the bottom of the pipe as it passes through the beaver dam sets a limit on how high the water can get in the pond before it overflows into the pipe and exits downstream of the dam.
As well, the corrugated interior of the pipe makes upstream swimming easier for adult salmon as they head to Cougar Creek’s best spawning grounds.
“Hopefully the beavers won’t notice the contraption, but will happily continue building their dam, unaware that the leveller limits their pond to a safe height that doesn’t flood the trail,” reads a press release from the Streamkeepers.
The beaver pond leveller is a joint pilot project of the Cougar Creek Streamkeepers, Burns Bog Conservation Society, City of Delta, EBB Consulting and the Pacific Salmon Foundation (PSF). In May, the foundation granted the Streamkeepers $1,129 for the pond leveller — a project valued at $2,287 — as well as $2,400 to the Burns Bog Conservation Society for Lower Cougar Creek riparian restoration.
The grants were awarded through the foundation’s Community Salmon Program, which supports volunteer and community–driven organizations that undertake salmon conservation and restoration projects in British Columbia and the Yukon, according to the PSF’s website.
“Though beavers are a nuisance, with their tree-cutting and dam-building, they are also a keystone species for healthy wetlands and salmon streams,” the Streamkeepers note. “A pond leveller is not maintenance-free, but we hope this one will reduce the amount of effort the City of Delta has to spend on dismantling beaver dams to prevent flooding. We’d all like to have our beavers, and our trail too.”
The leveller won’t completely eliminate trail flooding though, as the low level of the trail itself, combined with large volumes of stormwater runoff piped directly into Cougar Creek during rainy weather, guarantee that flooding will still occur.
However, in the coming years Metro Vancouver will be upgrading the trail and officially adding it to the Delta-South Surrey Regional Greenway, which currently runs from Mud Bay to 64th Avenue in North Delta and provides connections to the Boundary Bay Dyke Trail and Watershed Park in Delta, and Mud Bay Park and Joe Brown Park in Surrey.
As well, the City of Delta is continuing its efforts to reduce stormwater runoff at its source by diverting it into landscaping, including the more than two dozen rain gardens created by the Streamkeepers, instead of piping it into the creek.
“Meanwhile, whenever we’re faced with a slog through ankle-deep water [on the trail], we can recall how fortunate we are to have this relatively natural floodplain. Not only is it a safety-valve for protecting built areas from flood waters, it’s also a vibrant and healthy wetland habitat that nurtures fish, amphibians, birds and yes, those industrious beaver engineers,” the Streamkeepers say.