MUSKOKA LAKES - Residents living on Three Mile Lake are again being warned not to drink the water.
The lake, which is close to Windermere, has burst into bloom – blue-green algae blooms. The blooms release harmful toxins into the water, which can cause gastrointestinal symptoms.
Jerry Capko, manager of the Safe Water Program for the Simcoe Muskoka Health Unit, said it is at an early stage, so things are still uncertain.
“This isn’t something for people to panic about, but they shouldn’t drink the water, and they should be careful about where they go swimming,” he said.
The health unit released a public notice on Friday warning residents that if they are drawing water from a surface supply where algae is evident, boiling or other home treatment devices will not destroy the toxins. Well water in the area remains safe.
Residents faced a similar situation in 2005 when the bloom first appeared in alarming numbers the lake. Since then, they have taken precautionary measures such as reducing phosphate use, to try to prevent the situation from happening again.
Judi Brouse, director of watershed programs for the Muskoka Heritage Foundation, said there isn’t a definite answer to the cause of algae blooms, but she said phosphorus levels, the hot weather, sun, and lack of rain all contributed to the blooms - similar to conditions mentioned in 2005.
“These things all come together to create the perfect storm,” Brouse said.
It can also be washed away by a perfectly timed storm.
The toxin, microsystin, is released when the cells in the bloom are broken down, which often happens around this time of year. Naturally this process can last at least three weeks, but it’s unpredictable.
“Things can happen in between. If you have ideal conditions, it can last longer. If you have a storm and everything gets stirred up and blown away, it could end much sooner,” Capko said.
The Ministry of Environment found the blooms at both ends of the lake, but only the west end was above the safe drinking level. Capko said that doesn’t mean much because water moves and the tests are a few days old.
“The only thing we can confidently say is that the ministry of environment is continuing to test and we’ll see how things progress and inform people appropriately,” he said.
The health unit said the toxicity was not at a level that would cause skin irritations, but to take precautions.
“It’s a slowly evolving thing, it’s precautionary. It may or may not go into something serious,” Capko said.