Hamilton Public Health is telling people to avoid swimming in the west end of the harbour because of green surface scum.

Blue-green algae has been detected in the water and so Bayfront Beach has been closed to swimming. This is the second warning Public Health has issued about this area in a week.

“Residents are advised not to eat fish caught in these areas and not to let children or pets come into contact or drink from the water,” said Dr. Matthew Hodge, Hamilton’s Associate Medical Officer of Health. “Blue-green algae can be present in the water even in the absence of a visible scum and not all surface scums are toxic since they can be also caused by other, non-toxic algae.”

Blue-green algae produces toxins that have been detected at the western shortline of Bayfront Beach, and the Bayfront Park boat launch and Pier 4. Algae blooms “could be present or could arrive shortly” at other swimming areas in the harbour, public health says.

Some varieties of blue-green algae produce toxins and can irritate the skin. Adverse health effects are mostly caused by drinking the water, though skin contact with contaminated water can cause irritation and itching. Enough exposure to blue-green algae toxings can cause headaches, fever, diarrhea, abdominal pain, nausea or vomiting, skin rashes and mucous membrane irritation.

Anyone who has recently been in the water in the western areas of Hamilton harbour and is experiencing any of these symptoms should contact their doctor, Public Health says.

“It must be emphasized that the safety of Hamilton’s drinking water supply is not affected by this situation,” Public Health said in a news release. The health agency is continuing to monitor the presence of algae toxins in the harbour.