Don't touch the water at Pier 4 or let your dog drink it after blue-green algae bloom, expert says

Blue-green algae, recently detected at Hamilton's Pier 4 beach, produces toxins that can cause skin irritation, sore throats, swollen eyes and lips, fever, nausea and vomiting and diarrhea.

In other words, don't touch it. Don't let your pets touch it. And definitely don't let anyone (or any pets) drink it, says a McMaster University water scientist and policy analyst.

"A small dog could be killed if it was drinking that water," says Gail Krantzberg, a water scientist and professor in the university's masters of engineering and public policy program. "Do not let a dog off-leash near a water body that has blue-green algal blooms because the microcystin toxin is deadly. 

"The biggest problem with humans is if they ingest the water," she added, speaking to CBC Hamilton on Tuesday, days after Hamilton public health announced the harbour-facing beach had been closed after tests detected elevated levels of the algae, called cyanobacteria.

Her advice if you come into contact with water near Pier 4, or water looks to have the pea-soup look and petroleum-like sheen that the algae produces: "Wash in fresh water as soon as humanly possible."

The city announced July 4 that the beach was now closed, advising people in the area in a media release to "avoid all contact with the water along the shoreline of Pier 4 Park beach," located just west of the tugboat playground. 

Heavy rainstorms and intense heat create perfect conditions

That's not to say there isn't blue-green algae in other parts of the harbour, it's just that testing swimming beaches falls under the city's purview, so that is where they monitor, says Richard MacDonald, public health's manager of food and water safety.

For instance, the nearby Bayfront Park beach has been closed to swimming for years, so it is not tested by the city, he says. 

"Don't use it, don't recreate there," he said this week, noting areas such as public boat launches – including at Bayfront – fall under the scope of the provincial Ministry of the Environment, Conservation and Parks. "They do monitor and do respond to complaints."

Both MacDonald and Krantzberg confirmed that closing the beach on July 4 was early in the summer season compared to other years, stating that the combination of heavy rainstorms and intense heat has created the perfect conditions for the toxin-producing algae to flourish. 

The rains bring runoff, which includes nutrients such as phosphorus, into the water and feeds the algae, which is always present in the water but in diluted amounts, said MacDonald.

"It's not surprising" we're seeing a bloom right now, even if it is early in the season, he said, noting the calmer water in that area plays a role as well.

Algae blooms produce 'very putrid smell'

According to City of Hamilton's 2023 beach monitoring report, the Pier 4 beach was closed for six days last year due to blue-green algae blooms. It was also closed an additional 21 days for e. Coli contamination. The same year, blue-green algae blooms closed the beach at Binbrook Conservation Area for 20 days, in addition to the 29 days the beach there was closed for e. Coli. Those two beaches were the ones the City of Hamilton tests that saw blue-green algae blooms last year.

Krantzberg says the algae is very hardy once it has bloomed, and often stays present in the water well into the cooler months of the fall. She adds there aren't really any good ways to remove them as the bacteria releases the toxins when their cells are destroyed.

"If you have a dry and cool fall, they can die off, but once they've established, they will linger for very long periods of time," she said, noting they bear a distinct and recognizable aroma.

"There is a very putrid smell associated with the cyanobacteria, particularly as they decompose. You can have fish kills, [when the bacteria] absorb oxygen and small fish die, and that also adds to the unpleasant aroma or the stink."

'Go somewhere else for goodness sakes'

As climate change continues, and storms and hot temperatures happen more frequently, we can expect these early blooms to continue, Krantzberg says, noting the nutrients in the lake often come from runoff that can be agricultural or from the urban area.

"We just wash all the residue from our vehicle and from our fertilizers down the sewer system and they go untreated," she explained. "That's cumulatively a huge impact in an urban setting like Hamilton, sitting surrounded by agricultural lands.

"Until we get a really strong handle on agricultural  runoff, that's going to be an issue in Hamilton harbour for a long period of time."

She also noted that population density has an effect on cyanobacteria levels, as people increasingly live on waterfront land and clear away the plants that suck nutrients out of the environment.

"Removing natural vegetation to make nice grassy areas, that's a dangerous thing to do," Krantzberg says, while noting that thanks to improvements in sanitation and sewage treatment, the Hamilton harbour remains cleaner than it has been in a very long time. 

"People say, 'I remember when we used to swim in the water' – but [it] was really polluted then," she says, noting that even today, it's best to keep swimming and other water sports to areas with lower risk of blue-green algae. "Just go somewhere else for goodness sakes."