CONSERVATIONISTS are raising a red flag over some potentially toxic orange sludge that has started to build up around the mouth of Lynn Creek, and which they say threatens the stream's budding salmon run.
The substance began to appear in the creek after Port Metro Vancouver rebuilt a rail bridge and underpass for Brooksbank Avenue near Harbourview Park last year. It appears to be coming directly from the outflow of a new culvert that was installed to help protect the structure.
"The beach there is all red and looking really bad," said Doug Hayman, a member of the North Shore Streamkeepers. "This looks terrible."
But appearances aren't the Streamkeepers' biggest concern. Rather, the group fears the goo could endanger the salmon that they encourage to spawn there.
"We're raising coho salmon. Right now we have 5,000 coho fish that will be going in there next year, and this year we put in 3,000," said Hayman. "We get our brood stock out of Lynn Creek. We have to have all kinds of special permits to do this, and I just can't see how they would let this happen."
Hayman reported the rust-coloured slime to the Department of Fisheries and Oceans, but under the Fisheries Act, "deleterious substances" must be handled by Environment Canada. That agency has since been alerted, and will likely be visiting the area next week.
The sludge appears to be iron precipitate and bacteria, a naturally occurring substance that accumulates when low-oxygen, iron-rich groundwater mixes with oxygenated water at the surface.
The Lower Mainland's groundwater is very high in iron that largely lies dormant, according to John Werring, aquatic habitat specialist with the David Suzuki foundation, but when it reaches the surface, it can drastically change an ecosystem.
"It can be very, very problematic," Werring said. "It can actually cause toxicity to aquatic organisms, and cause lethality in fish if it's extensive."
Beyond that, it is likely to edge out the green algae usually found in the area, which is grazed on by insect larvae and snails. Those invertebrates, a food source for fish, can't survive on the iron bacteria orange slime.
"Essentially, it's part of the food chain," Werring said.
Luckily, the damage appears to be limited the mouth of the creek at this point, said Werring. "Normally these things are more of a nuisance from an overall productivity of a stream perspective, unless it is extensive," he said.
Port Metro Vancouver staff are now looking into the problem with Environment Canada. The port agrees iron precipitate is the most likely culprit, according to Kim Keskinen, a PMV environment specialist.
"That's our best guess at the moment," she said. "We'll be meeting (Environment Canada) on site on Monday and taking some samples and looking into it. That would seem to be what it is, but we don't know for sure yet."
The port installed the culvert and an adjoining pump station to draw ground water away from the underpass and prevent flooding, freezing and other events that could damage the new structure.
It's not clear, though, that the resulting iron precipitate is a threat to fish, said Keskinen. "That is another thing of debate."
Clearer information about the problem and how to fix it won't be available until at least next week, she said.
"Hopefully, we'll be able to confirm that it's simply iron precipitate and how we can address it, if we can," said Keskinen.
If it's an iron problem, it shouldn't be too hard to solve, Werring said. Instead of pumping the water into the culvert and creek, it could be redirected somewhere inland or to a freshwater body that can tolerate the increase in iron - or into sewage treatment.
But Hayman, who would like to see the problem resolved at its source, isn't sure it can be addressed that easily if it would mean rebuilding the bridge.
"They've spent a lot of money," he said. "They've got railway tracks and all that stuff down there. They're not going to pull that up, but something should be done."