A Toronto city councillor says he has the answer to the great city stink mystery that took over social media Thursday.

Mike Layton tweeted Friday morning that the smell is organic fertilizer applied to the fields by the Parks and Recreation Department.

Layton, the Ward 19 councillor, said this is something that is done annually to all fields in the city and some horticultural beds.

He said that in his ward alone, which includes Queen West, Little Portugal, Trinity-Bellwoods Park and more, about seven fields were treated.

"It smelled like eggs and sulphur," said Wilbur Huang, who was walking downtown on Portland Street near King Street when he was hit with the stench. 

Huang told CBC Toronto he assumed it was coming from the sewers.

Laura Magisano thought it was likely emanating from the patties police horses leave on the streets.

"But when I walked for another 10 minutes and still smelled it, I really didn't know what it was. It was unpleasant to say the least," she said. 

Many grossed-out Torontonians — and people in surrounding communities — inundated Twitter and Reddit with complaints about a manure-like smell taking over the Greater Toronto Area. 

Many theories blamed dogs and farms, and some even questioned themselves.

One Reddit user said the stench carried from home in Richmond Hill to the school campus.

"It smelled funny north in the Richmond Hill area and I'm on campus at Bayview and Lawrence and it smells like poop here too what gives," said the user.

The complaints stretched across the GTA from Mississauga, to Brampton, Georgetown and more.

Layton said he didn't know why the smell was so far reaching, but the farms in those areas could be a contributing factor.

He also said there have never been this many complaints.

"It's a little warmer, the winds may have been different, but we typically don't get complaints like this," he said.

A similar smell plagued the city a few years ago, when the Ministry of Environment linked it to rotting leaves after a stretch of warm fall weather.

This also happened in the spring of 2011, and again, environmental officials cleared up the confusion, blaming the spring thaw for the unpleasant smell.