The Province of Manitoba is responding to concerns from Portage la Prairie residents about worsening weed growth and uncertain water levels at Crescent Lake.
Thick vegetation has been building up across the lake this summer, and city officials say they’re limited in how they can manage it. At the same time, the city has had to pause its usual practice of pumping water in from the Assiniboine River, something that’s been done for decades, due to rules connected to aquatic invasive species (AIS).
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Herbicides not allowed in fish-bearing waters
The province confirms that federal law blocks the use of chemicals in bodies of water that contain fish.
“Although native vegetation in waterbodies like Crescent Lake can affect how people use those waterbodies, the application of herbicides to fish-bearing waters is prohibited by federal law,” notes the province in a written statement.
City Director of Operations Jocelyn Lequier-Jobin says the chemical the city used in the past, known as Reward, is no longer permitted because Crescent Lake is now considered a fish habitat.
She explains that weed growth has been particularly heavy near the west end of the lake and says the city is currently seeking approval to use mechanical harvesting instead.
Zebra mussels bring new water pumping restrictions
The province also confirms that new restrictions on pumping from the Assiniboine River are in place because the river is part of an AIS control zone.
“Manitoba’s Aquatic Invasive Species regulations have been in place for ten years to help prevent the spread of AIS,” says the province.
Lequier-Jobin mentions that without the ability to pump during dry summers like this one, the lake level drops quickly due to evaporation. She also warns that low water could impact recreation, weed removal efforts, and even fountain installations, all of which rely on boats being able to access the lake.
The province says it is already in touch with the City of Portage to explore future options.
“The Assiniboine River where Portage la Prairie pumps from is part of an AIS control zone, and the province has had discussions with the City of Portage on ways to mitigate the risk of spreading AIS as part of future plans for Crescent Lake pumping,” continues the province.
City, province working together
For now, both the province and the city say they’re committed to finding long-term solutions. The city has pumps and infrastructure in place and is waiting on provincial approval to begin using them again.
“We are looking for some methods that we might be able to use to get water into the lake,” Lequier-Jobin adds. “But it’s going to take a bit of time to figure that out.”
As for weed control, harvesting can only happen from mid-June to mid-September, outside of fish spawning season. Lequier-Jobin remarks that mechanical removal could reduce regrowth in future years.
“They do say that as you do it each year, it tends to reduce the regrowth in future years,” she says.
The province is asking all communities to do their part in protecting Manitoba’s lakes.
“All communities need to work together to stop the spread of AIS and prevent permanent damage to lakes and other waterways,” it emphasizes.
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