Lake Temescal closed to swimmers due to the detection of a blue-green algae bloom Monday, which can produce dangerous toxins according to the East Bay Regional Parks District.
The algae can produce kidney, liver and neurotoxins, according to Water Management Supervisor Hal MacLean. They can cause skin rashes in humans, but consumption of the toxins can be fatal for dogs.
“I think it can be fatal for anything that drinks enough toxins. … The problem with dogs and livestock is that they’d be exerting themselves, then they’d go and drink a lot of water and that’s how they’d get the exposure. … For humans, generally, you don’t go in the lake to drink a lot of water.”
Blue-green algae blooms are an annual problem in bodies of water throughout the region. They’re often associated with warmer temperatures in stagnant or still waters, but MacLean said the lake is a complex ecosystem and it’s hard to be certain which factor is responsible.
“I’m not sure exactly why we’re having a bloom. … It does have to do with higher temperatures. Some how (the algae is) getting a foothold, taking off and out-competing.”
The lake is still open for fishing but there is no estimate for when it will reopen to swimmers. Other uses for the park, including picnics, bird watching and jogging, are not affected.
Lake Temescal is located near state Highway 24 and state Highway 13. It was opened to the public in 1936, and originally built to store drinking water, according to district officials.
It is tested for bacteria on a weekly basis from April through October.
Even in good water conditions, district officials say there is always some risk. Swimmers are advised to keep water out of their mouths, to shower as soon as possible after leaving the water and to avoid swimming for at least three days after a rainstorm.