Nutrient trap devices are bing installed in waterways that flow into Quamichan Lake in an attempt to improve water quality and discourage deadly blue-green algae outbreaks.
The Municipality of North Cowichan installing the traps, which contain a mixture of zeolite and limestone, in ditches and streams flowing into the lake. The nutrient traps are an experimental approach to filter the water entering the lake, thereby reducing phosphorus, which can create an environment that favours blue-green algae, a press release from the municipality said.
“Protecting and enhancing the environment, including Quamichan Lake, is one of Council’s key strategic priorities,” says North Cowichan Mayor Al Siebring. “Treating streams and ditches that flow into the lake with zeolite and limestone was a key recommendation to come out of 2019’s Quamichan Lake Blue-Green Algae Management Report, and we’re eager to hear the results of this approach. If proven effective for Quamichan Lake, the nutrient traps could also be used to treat runoff water from farms and neighbourhoods near other local watersheds like Somenos Lake, Fuller Lake, and Bonsall Creek.”
The health of Quamichan Lake has been a focus for North Cowichan since concerns were raised during a blue-green algae bloom in the summer of 2016 that killed several dogs in the area that swam in the water, and ingested the algae.
While blue-green algae is not uncommon in shallow urban lakes and has been present in Quamichan Lake since at least the 1930s, the blooms have become more intense and longer in duration in recent years.
“Studies in agricultural and wastewater treatment settings have shown that this mixture of minerals can be successful in removing phosphorus from water that it meets,” says Dr. Dave Preikshot, North Cowichan’s senior environmental specialist. “Our team will now monitor the concentrations of phosphorus in the water upstream and downstream of the nutrient traps to monitor the success of this approach.”
Quamichan Lake was also chosen in 2019 to become a national training centre for the Canadian rowing team.