Local conservationists are sounding the alarm after witnessing a localized fish kill in North Delta’s Cougar Creek last weekend.
On Aug. 20 and 21, the B.C. Wildlife Federation and Cougar Creek Streamkeepers hosted a fish habitat stewardship workshop at the Westview bend of Cougar Creek.
The waterway, which flows roughly west from Cougar Creek Park in Surrey before turning north below Westview Drive and meandering through the Delta Nature Reserve on its way to the Fraser River, is an important local spawning channel for chum and coho salmon, cutthroat trout and other species.
According to a BCWF press release, as environmental chemist Josh Baker was explaining to participants the dangers that toxins pose to salmon- and trout-bearing streams, workshop participants observed at least two dozen dead salmon and trout in the creek.
The fish, the release states, were apparently poisoned when toxic compounds were flushed into the creek by untreated stormwater from a nearby road.
“Participants from all over the Lower Mainland got to observe the fish kill firsthand,” Streamkeeper Pete Willows said in the press release.
Neil Fletcher, BCWF’s director of conservation stewardship, said events like this are most often due to urban pollutants entering a stream during the first rain after a dry period.
“The low flow combined with a higher concentration of pollutants is a recipe for disaster,” Fletcher said in a press release.
To reduce the concentration of toxins that enter local fish-bearing streams and creeks, Willows believes North Delta could benefit from a “first flush system” that directs rainwater into vegetated areas that help filter out compounds toxic to fish — something that’s especially important after long periods of no rain.
“Our community has an amazing salmon-bearing stream, right in the middle of our community. There are so many things that can be addressed — from education to development practices — that could improve our relationship with the natural environment,” Willows said.
Fletcher said salmon in urban watersheds benefit from integrated stormwater management techniques that “consider how a drop of water moves from our communities to the ocean,” noting the fish are indicators of environmental health.
Solutions can incorporate green infrastructure such as restored wetlands to filter pollutants (a “natural and permanent” line of defence, Baker said), sediment retention ponds, rain gardens and the provision of side-channel habitats.
“This should be in combination with both public education and more engineered solutions closer to the source to limit the amount of toxins released into our waterways,” Fletcher said, adding more investment, resources and attention from all levels of government are critical to support healthy watersheds.
“We invite the City of Delta to engage with the BCWF and the Cougar Creek Streamkeepers to generate effective solutions to this entirely preventable scenario,” Fletcher said.
Tuesday’s press release noted the BCWF and Cougar Creek Streamkeepers will be back at the site later in the year to improve the riparian corridor (i.e. the creek’s banks and adjacent vegetated areas), remove invasive plants and introduce native plants and shrubs to mitigate some of the effects of urban encroachment.