An outbreak of avian botulism has been reported at Lakeside with RSPCA officers recovering the bodies of dozens of birds over the last few days.
Now Doncaster Council chiefs have urged members of the public and their pets to stay out of the water while the process of recovering the bodies of dead birds and rescuing others in distress goes on.
The outbreak was caused by this summer's heatwave and is the second tragedy to hit the town's bird population in recent months following the deaths of 100 ducks at Sandall Park.
RSPCA inspector John Gibson said the illness was down to the recent hot weather causing low water levels that led to rotting vegetation increasing the level of toxic algae.
"We have rescued a number of swans and other water birds who are responding well to treatment but many more have been found dead or had to be put to sleep," he said.
"We are removing the bodies as not doing so is known to increase the concentrate of the toxin and are urging people not to feed the swans."
In a statement, Doncaster Council said: "The water has been treated with a non-toxic and eco-friendly blue-green dye to control aquatic weeds that can sometimes cause other problems.
"It is not harmful but we would recommend that residents and their pets do not go in the water."
At Sandall Park, deadly blue green algae wasÂ confirmed and the Council has been working with theÂ Environment Agency to address the problem over a number of weeks.
Read more at: https://www.doncasterfreepress.co.uk/news/investigation-under-way-after-ducks-die-at-second-doncaster-beauty-spot-1-9307093