Is it shaping up to be another bad summer for blue-green algae blooms on popular lakes in northern Ontario?
Blue-green algae, which can be toxic for humans, animals and fish, used to be mainly the bane of southern Ontario waterways.
But one could be forgiven for thinking the poisonous scourge has become a regular sight in the North, following another public-health advisory regarding Surprise Lake, a cottage haven just north of Thunder Bay.
It’s the third time since 2019 that the small, narrow lake has been hit with an algae warning, though tests on water samples in the two previous incidents showed they weren’t toxic.
Results from a sample taken on June 19 from Surprise Lake’s southern tip were still pending on Friday. Tests, which can take up to five days, are overseen by Ontario’s Ministry of Environment, Conservation and Parks.
Even if tests come back negative for any toxicity, people who make use of a waterway where algae was found should still exercise caution, especially if the bloom is still visible, experts say. Typically, blooms create a turquoise sheen on the water’s surface.
“A water sample provides a snapshot only for that particular day,” noted Thunder Bay District Health Unit public-health inspector Matt Bradica.
Algae blooms usually form and thrive in summer when lake and river temperatures rise, a phenomenon often compounded by excessive amounts of phosphorous.
Warming lakes have been linked to climate change, while high amounts of phosphorous has been linked to grey water from household appliances like clothes washers and dishwashers, as well as septic systems.
Though Surprise Lake is no longer known as a mecca for great fishing, some anglers continue to catch walleye and other species there.
Bradica said it’s not a good idea to eat fish caught in areas where blooms are spotted, since toxins can be absorbed in their organs.
It’s been estimated there are about 85 cottages on Surprise Lake, which is located in unorganized Gorham Township.
A spokesman for the Ministry of Natural Resources and Forestry said that while it doesn’t have a “primary role” in controlling development in unorganized areas, it does require permits for erecting structures, or for making alterations to land and waterways.
The health unit also inspects and approves septic systems, including some that were installed on Surprise Lake, to ensure “the proposed system is meeting minimum distances from any lake, pond, river, stream or any other body of water.”
During the hot summer of 2021, the public health unit issued eight warnings for blue-green algae across the Thunder Bay district, the most ever in a single season. Surprise Lake wasn’t on the list of reported blooms that year.
According to the Ministry of Environment, lakefront property owners can reduce their phosphorous output in a number of ways, including “using phosphate-free detergents, not bathing in lakes, maintaining naturalized shorelines, not using fertilizers . . . and ensuring that septic systems don’t leak or discharge into water bodies.”