A bloom of poisonous algae is killing birds in Lake Zug and the canton is warning people not to swim and keep their dogs out of the lake.
The algae is commonly known as ‘blue-green algae’ – although in this case, it’s a burgundy colour.
The canton says there’s little it can do as it’s a totally natural phenomenon.
Experts say the algae is formed when there’s a combination of sunlight and cold weather as warm water, where the algae live, floats to the surface and then its fed by the light.
In June a similar bloom killed a dog in canton Neuchatel.
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