The B.C. Ministry of Environment is looking into a leak from a local business that poured iron oxide into Matsqui Slough earlier this week, turning the waterway a reddish-brown colour.
The slough bore an intense rust colour at Harris Road, where it passes metres from a sign declaring it a salmon habitat.
Al Dutra, who lives next to the slough, noticed the discoloration Wednesday morning.
“I was a little worried,” he said. “I thought, ‘Holy doodle.’”
The city was already on the case, and told Dutra the cause of the change in colour.
Iron oxide is a common compound, and is widely used as a colouring agent. It also occurs naturally as rust. On Wednesday, the slough’s colour became normal further downstream where the water passes beneath Riverside Street.
That offered some comfort to Dutra, who keeps llamas and grows strawberries at his home.
“I thought it was something that got spilled, something poisonous,” he said. But he still has some concerns.
“It’s not normal,” he said. “I’ve been here a long time.”
The city’s director of engineering, Jim Gordon, confirmed the iron oxide spill, although he did not identify the business involved.
“We believe the source of the leak is now fixed,” Gordon said. “The ministry of environment is working through mitigation.”
Neither the B.C. nor Canadian environment ministries were available for comment at press time.
Iron dust isn’t toxic but can have a dramatic effect on bodies of water.
In 2012, a B.C. First Nation and a salmon company drew flak after dumping iron dust in the Pacific Ocean in an experiment designed to fertilize the water, and spur a plankton bloom. The idea was that the iron dust would both help the salmon and trap carbon underwater, but the experiment sparked criticism from a range of organizations worried about unforeseen effects.
While the sockeye have begun their annual spawning run, a 1997 study noted that the Matsqui Slough would be favoured by coho and chum salmon, which spawn in the fall.
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