The City of Abbotsford is investigating after residents witnessed large pillows of foam floating in a local creek a few days after a white powder was spread on the rooftops of a nearby townhouse complex.
Tom Ulanowski, who has lived at the complex at 4401 Blauson Blvd. on the side of Sumas Mountain for five years, said he's concerned the foam will harm wildlife in and around Clayburn Creek.
"I was quite shocked and concerned," he said. "Literally, there were piles of foam eight feet high in some areas."
Officials with the province's Ministry of Environment said they, along with the City of Abbotsford and Environment Canada, are monitoring the situation, but confirm the substance causing all the foam is Tide powdered detergent.
Using laundry detergent to deter moss from growing on roofs is a remedy easily found through an online search, but it also comes with warnings that the technique does not work, or worse, can damage roofs.
Health Canada regulates pesticides in Canada. Tide laundry detergent does not specify on its label that it can be used as a herbicide. Detergents contain surfactants and bleaches to break up stains that otherwise wouldn't dissolve in water, according to ingredient listings.
Ulanowski, an environmental scientist and analytical chemist who works in the cannabis industry, first saw a contractor applying what looked like detergent powder to roofs at his complex on Monday.
He and other residents saw some of the detergent blow off the roofs and end up in residents' yards and gardens. Ulanowski said some people and at least one dog suffered irritation from the detergent.
He and another resident brought their concerns to the strata's council before the foam started to appear Friday morning, following rain on Thursday.
After the foam was reported, the City of Abbotsford sent crews to inspect the creek.
The city's bylaw department is also investigating but has not said whether there will be any penalties to the contractor or strata for use of the detergent.
The province said the contractor has been asked to take action to clean up the foam, but said there doesn't appear to be any negative impacts on fish habitat.
Environment Canada has not responded to media requests for information about how it is responding to complaints about the foam.
CBC News also sent messages to the complex's strata management firm and the person believed to be the contractor who applied the detergent, but has yet to receive a response.
Ulanowski hopes the saga will serve as a warning to other property owners who may think it's a good idea to use laundry detergent as treatment for moss on roofs.
"Ultimately I just want people to be aware that there are better, more environmentally friendly options for things like moss control," he said.
"Using things like detergents and bleach that can persist and make their way into the aquatic environment is not an environmentally friendly solution and there can be severe consequences, potentially."