Though it's not quite the season for it yet, it seems that foul-smelling, potentially even toxic algae is already forming on Toronto's waterfront, spurring residents to warn one-another to stay away — especially if they have pets.

Algae is not uncommon along the city's shores, but it certainly is unpleasant, emitting a stink comparable to rotting garbage and making our beaches look icky.

What's worse is that that if pets are exposed to the certain types of the stuff — cyanobacteria or blue-green algae in particular — while playing in the water, they can become very ill with symptoms that range from vomiting and diarrhea to paralysis, seizures and even death if it is the ingested in high concentrations.

As one person noted in a local Facebook group for dog owners in the Cherry Beach area, algae blooms appear to be collecting early this year, and could be extremely dangerous for pups.

A citizen alerted fellow pet owners to the sludge collecting on the water near Cherry Beach, which they added in a comment, has gotten worse since they first spotted it on May 9. Post from the Cherry Beach Dog Owner's Association Facebook group.

A photo they shared to the group last week shows a mass of the grey, yucky-looking and smelly gunk, which the individual said has grown in size in recent days and is especially bad around the Toronto Harbour Lighthouse in Tommy Thompson Park.

Many speculated that warming temperatures will only make the smell and size of the bloom — which usually occurs in late summer — worse.

Advocates and experts have been documenting earlier and more frequent harmful algal blooms in Canada and around the world lately, something they attribute to climate change, warmer water temperatures and higher carbon dioxide levels.

Toronto is snowy then beautiful weather then snowy and then cool weather and then we get a heat 1 heat wave and we have algae blooms and no one can touch the water and all the fish in lake Ontario die and the whole lake shore smells like rotting corpses and then you wanna puke

— Bobo (@HoodSheikh) April 16, 2024

Scientific American writes that whether this phenomenon is strictly bad "is a murky question," as "algae are an important food source for many marine animals, and large blooms can sometimes be a benefit for ocean ecosystems and fisheries... but some algal blooms also release toxins into the water and poison the environment."

Dead and decomposing blooms, along with being incredibly pungent, can also reduce oxygen concentrations in the water and thus disrupt the ecosystems — and harm pets, humans and other animals.

Vets generally advise owners to err on the side of caution and consider any and all algae blooms to be dangerous, and to stay away from them completely.

The Ontario Ministry of the Environment, Conservation and Parks, as well as the City of Toronto, were unable to confirm whether this bloom in particular is the blue-green kind or something non-toxic.