In a meeting in Dartmouth Thursday night, the city of Halifax outlined three options to deal with weed infestations in Lake Banook and Lake Micmac in Dartmouth.
The weeds hamper rowers and swimmers and have prompted complaints to the city.
"The racing kayaks are very tippy, so if you were to take a stroke and catch weeds, there'd be a good chance you could fall out of your kayak," said Fred Van Horne of the Atlantic division of CanoeKayak Canada.
The problem started in 2009 after the water level was dropped in the lakes to install a pipe along the shore, according to Cameron Deacoff, an environmental performance officer with the municipality.
"When that water level was lowered for that work, what happened is that the sediments at the bottom of those lakes were exposed to more light and wind and oxygen than usually happens," he told CBC’s Information Morning.
"The plant matter that was already residing in the sediments there had the chance to grow in a way that they didn’t before."
He said the weed problem is most prevalent in shallow waters near shore.
Three possible options
The most expensive option to deal with the problem is to dig up and remove the sediment, a process that would cost about $1 million a year.
The city could also chop plants with an aquatic lawnmower-like machine. The device costs between $100,000 and $300,000, and the city would spend another $20,000 a year to operate it. Contracting out the work would cost about $180,000 a year, Deacoff said.
The least expensive option is to use an aquatic herbicide to the kill the weeds. It would cost about $119,000 per year.
A report to the city said there's no danger to humans or wildlife if the herbicide is applied properly.
"I guess I just really don't want to have to tell my daughter that the lake's closed because it's poisoned a week each year for the next five years," said Pam Rubin, a Dartmouth resident at the meeting.
Deacoff said Thursday’s meeting is a chance for city staff to gauge what people in the community want to happen with the lakes.
The final decision is up to the Halifax council.