The video was being circulated on social media Tuesday.
Acting as a mock tour guide of the geyser, which was caused by a broken water main at a construction site, Stewart jokes the water blasting high into the sky directly behind him is a "natural" occurrence.
"Hi, we're in Montreal, Quebec, in front of the famous geyser," Stewart tells the camera.
"A little known fact — this geyser has existed in Montreal all these years and nobody has uncovered it."
The broken water main burst on Tuesday at around 2 a.m., leading to the closure of several blocks of St-Laurent, a main street running through Montreal's Plateau-Mont-Royal borough.
The road had reopened by around 10 a.m.
Another resident, who captured the geyser from farther afield, wondered why it took so long for city crews to arrive.