Following reports on social media of algae blooms on Horse Lake earlier this month the Ministry of Environment and Climate Change Strategy is asking the community to report any further algae blooms.
In a statement emailed to the Free Press, the ministry noted algae blooms typically take place in favourable conditions such as hot temperatures, increased nutrients, lots of sunlight and stable wind conditions, all of which were in play on Aug. 1 when members of the community posted photos of green algal blooms to social media. The ministry said that these blooms can also be caused by runoff from human activities, such as residential areas and agricultural operations.
"Additional nutrients can increase the risk and severity of a bloom, however; run-off with additional nutrients do not always lead to blooms if the other conditions aren’t favourable," the ministry said. "High turbidity from run-off or wildfire smoke can limit the light penetration into the water which then can prevent excessive algal growth."
The ministry noted that green algae blooms, like the one reported on Horse Lake, are not harmful to humans but are displeasing and can clog filtration systems. The algae people should look out for is cyanobacteria, which is a type of blue-green algae that appears naturally in freshwater lakes.
When cyanobacteria blooms it can produce toxins that are harmful to humans, pets, livestock and wildlife if ingested or absorbed through the skin.
"How much and under what conditions cyanobacteria will produce toxins is still unclear, so it is better to be safe and stay out of the water when there is an algal bloom," the ministry noted. "If water from a lake with an algal bloom is being used for domestic purposes (washing and drinking), it is advisable to use an alternate source as boiling does not remove the toxins."
The ministry said that as part of the British Columbia Lakes Monitoring Network Program Horse Lake's water quality is monitored twice annually, once in the spring and once in the summer. They noted its next sample is scheduled to be taken this month which will tell them how many nutrients and chlorophyll is in the water.
Based on samples taken in 2021 and 2022, they noted Horse Lake tends to develop algae blooms in the middle of the lake during the summer. While the potential for algae blooms is elevated, they noted that the production of cyanobacterial toxins is unlikely and that Horse Lake's chlorophyll levels tend to be lower than other lakes in the Cariboo.
The public is encouraged to report any concerns about algae blooms of any kind on any lakes by going to the environmental public health feedback page at interiorhealth.ca or gov.bc.ca's algae watch page.
