Toxic algae makes early appearance in harbour

Toxic blue-green algae has made an early appearance in Hamilton Harbour this year.

On the upside, both city beaches in the harbour are already closed to swimmers.

Public health officials have confirmed the presence of the toxin-producing algae near the Bayfront Park boat launch and beach as well as at Pier 4 Park beach. Tests show concentrations of the toxin microcystin at levels beyond 10 parts per billion, the threshold the city uses to issue a warning.

It’s also likely algae is present near Pier 8, local marinas and west to the closed Waterfront Trail, said water quality manager Eric Mathews. “This is earlier than we would normally expect,” he said, noting past alerts have typically come in late July or August.

The city warning is aimed particularly at boaters, windsurfers and other regular harbour users who might regularly touch the water. Beachgoers should also avoid swimming in the harbour — but Bayfront beach is already permanently closed due to poor water quality, while high water levels have closed Pier 4. Ingesting water contaminated with the algae-produced toxins is the greatest health risk, Mathews said, but coming into “incidental contact” with the polluted water could also cause skin irritation and itchiness. If you do touch the water, try to quickly wash your hands, Mathews said.

Drinking the water could lead to diarrhea, abdominal pain, headaches and fever. Anyone who experiences those symptoms after being in contact with water in those areas of the harbour should call a doctor, says a city release.

It’s not clear why the unwelcome cyanobacteria showed up early this year. But record rain and lake levels have contributed to more sewer overflows into the harbour, which provides more nutrients for algae.