Stormwater in North Delta should be managed better before it rushes into nearby creeks and streams, say the Cougar Creek Streamkeepers.
“North Delta could benefit from a first-flush system to reduce the concentration of toxins that enter the water,” said Pete Willows with the Streamkeepers.
Such a system would direct stormwater from local roads on to vegetated areas, before running into local creeks.
“It is extremely important during long periods of no rain to direct the first flush of water from road surfaces into vegetated areas to keep the accumulated toxins out of the watercourses,” Willows said in a news release issued by the B.C. Wildlife Federation.
He was commenting after the Streamkeepers hosted a workshop at the creek Aug. 20 to 21. During the workshop, participants found about two dozen dead baby salmon and trout at the Westview Drive water discharge culvert.
The wildlife federation news release said polluted water runoff apparently killed the fish but wildlife federation environmental chemist Josh Baker said that’s not likely, saying there was a little drizzle over the weekend, but not enough to flush any stormwater into the creek.
As well, people smelled chlorine around the creek on Saturday, saying the fish kill could have been caused by someone dumping swimming pool or hot tub water down a curbside storm drain.
Water temperatures in Cougar Creek were normal at 17 C and water quality tests on Sunday didn’t show any pollutants, Baker said.
“It was likely somebody just dumped something,” he said.
Delta city manager Sean McGill said it’s not possible to confirm that stormwater was the cause of the fish kill.
“A reported chlorine smell and presence of suds in the creek are other potential, unconfirmed causes. It is unfortunate that the press release from the B.C. Wildlife Federation included statements around cause, when to our knowledge this was not determined,” McGill said.
The death of the fish was difficult to see for the Cougar Creek Streamkeepers who work hard to restore salmon to the creek.
Baker said about 200 adult coho return yearly to a stream in a highly urbanized area.
“I think the Cougar Creek folks have seen this a couple of times now,” he said.
Cougar Creek is a rearing area for chum and coho salmon, cutthroat trout, and other species.
He pointed out that all of the stormwater from Metro Vancouver roads runs directly, untreated, into local streams. During winter, when water levels are high, the pollutants are diluted but during summer, with low water, they’re concentrated.
Wetlands could be improved so they absorb stormwater and purify it before it reaches a stream, said Baker.
The City of Delta, in this particular location, could modify the outflow pipe so it flows on to a nearby vegetated area, before then draining into Cougar Creek.
“It’s one of the few known locations that are problematic so it’s an easy solution. That would be our hope is they can help move that forward,” Baker said.
Generally municipalities ensure water is treated adequately, through such things as integrated stormwater management plans, he added.
“Soil is still the best biotreatment we have,” Baker said.
Stormwater management can include wetlands, sediment retention ponds, rain gardens, and stream side channel habitats.
McGill said the city takes the protection of waterways seriously.
“We continue to install rain gardens and other green infrastructure to collect and infiltrate stormwater into the ground, which cleans and cools the water before it enters streams,” McGill said.
The city also lends out storm drain marking kits to schools and community groups to paint yellow fish next to storm drains, so people know that all drains lead to fish habitat.
“Delta’s school rain gardens all have signage talking about the importance of clean stormwater and we periodically undertake other public education initiatives to increase awareness,” McGill added.
McGill said Delta applied for a grant under the Investing in Canada Infrastructure Program – Green Infrastructure – Environmental Quality Substream for Cougar Creek Enhancements (Westview Bend/Huff Corridor).
He said their application was denied in July 2021, but the city is planning to apply for another grant for the same project.