The Department of Agriculture and Rural Development (DARD) has issued a warning to local people visiting Hillsborough Forest that the lake is currently covered with blue green algae, which is adversely affecting the quality of the water.
The warning comes after a dog was left with gastroenteritis after swimming in the lake recently.
A concerned owner had posted on an animal lovers Facebook page to warn people that swimming in the lake had made her dog very ill.
“He was in the water and that night he was sick and slowly got worst of the next couple of days,” she explained.
“He is now on medication for severe gastroenteritis.
“I was unaware that their is an on going problem with the quality of the water at Hillsborough Lake and although I have been told there is signage up about this we were unable to see any.”
Another local resident was also concerned about the swans and ducks that have made their home at the lake.
“Seven signets all died in the space of a week,” she said. “There are no seagulls anymore and there are now only four swans.
“Two years ago there were forty swans at the lake but that number has dwindled considerably.”
A spokesperson for DARD explained that warning signs had been erected around the Forest to warn visitors about the algae on the lake.
“Blue-green algae are typically found in nutrient rich waters such as Hillsborough Forest lake,” she said.
“The concentration levels of these algae are affected by factors such as rainfall, and due to recent warm weather and lack of rain algae levels may have increased.
“Warning signs are in place at public access points to remind visitors of the need to avoid coming into contact with the water.”