The McTavish Reservoir exposed

Andrew Chau has a great post on the McTavish Reservoir today at urban-ism:

many people don’t realize that the large grassy field above the mcgill campus hides enormous tanks of water that feed into the city’s water systems. the curious castle-like structure that seems so out of place, the strange manhole covers that litter the fields, and the artificial flatness of the site are hints of what lies beyond. the cavernous spaces below are from another world: the underground grottoes of the stockholm metro, the troglodyte dwellings in matmata, the sahara.

where people now play a game of soccer or frisbee, or lie down with a book to read on the grass, there once was an open-air water tank encircled by an idyllic carriage-path. the medieval castle looked appropriate to the scenery, and the picturesque view overlooked the developing city.

this is leagues away from what the site is like now. the 13.5 million gallon open air reservoir has been covered over by a concrete slab, and a layer of soil and grass have been planted atop in order to sanitize the infrastructure. the castle-like structure now houses the pumps, and the carriage-way is a jogging track. the underground tanks are still the primary holding tank and distribution point for the city, but are now unbeknownst to most residents nearby.

Here’s a bit of historical background on the reservoir. It was built between 1853 and 1856, with natural rock used to hold the water. It was 24 feet deep and held 13.5 million gallons of water. In 1862, it was enlarged to hold 16 million gallons, and then enlarged again in 1877 to hold 37 million gallons.

The castle-like pumphouse was completed in 1932; its six pumps, now fully automated, suck water out of the St. Lawrence River through a series of aqueducts. In 1957, the reservoir was covered. No changes have been made to it since then.

What I want to know is why the reservoir was covered. Anyone?

Photos by Andrew Chau; map courtesy McGill University


  1. Recently, they have begun some sort of covert work operation on the reservoir. The city set up this tarp-walled structure on the resrvoir, in which all work happens…at night. When I went to walk my dog there, a man greeted me at the entrance shaking his finger, indicating blocked access to the reservoir.

    Turns out they’re protecting the reservoir – and two others on the island – against “terrorist threats” nowadays, as this Le Devoir article dated Oct 5 states:

    In 2003, a TQS reporter managed to enter the Atwater filtration plant undetected, access the main control panel, and even dip his hand in the reservoir. He aired his report on TV, and everyone turned paranoid. I assume something like this led the city to cover the resrvoir in the first place.

    On another note, the castle was built by a Swiss family called the Dubayes (unsure spelling) whose descendants live on Cote-st-antoine in westmount nowadays. They have all the original plans as drawn in the day posted on their home’s walls.

  2. I would guess it was covered for health and safety, you don’t want people skinny dipping or drowning accidentally in it, and since water from the St. Lawrence is first pumped to a water treatment site somewhere outside the city (I forget where exactly) and then this clean water is stored in those tanks, you don’t want it exposed to falling dead leaves and other debris (natural or otherwise). Yes we’ve come a long way in water treatment, and there’s still more to come.

    U2 Civil Engineering, McGill

  3. I believe a lot of reservoirs in NA started to get covered in the 1950s because of the “Red Scare.” It was thought that communists could easily poison the city’s water supply. Given that, it’s not surprising that they’re now taking additional steps to guard against terrorist activity during today’s post-911 hysteria. I’m more surprised that it’s actually taken them this long to get around to doing it.

    There are actually several of these underground reservoirs scattered around the city. Mactavish is the oldest and probably the most interesting of the lot, but it’s only the fourth largest in terms of overall capacity. From what I’ve heard, similar efforts will be made to secure some of these other ones as well, most likely by welding manhole covers and installing motion detectors in the spaces surrounding the tanks.

  4. From what I undestood, the city is only going to protect the bigger ones. They aren’t welding them though; just putting locks on top of the covers, like some already had. Still, that’s never enough considering their ”terrorists attacks”. I’ve walked on McTavish two weeks ago and all I can say is: Please, get someone to do the job, and do it right, the system is currently a pile of *censured word. Come on, my house is even more secure than thoses reservoirs with only one Teckel. I can’t complaint of the lack of security, I like it this way if it’s not even less, but if you’re about to do it, do it correctly. Seriously, if someone really wish to make it unusable, he will. Go get Batman, he will secure thoses places properly.

  5. I heard the reservoir was covered because of the fallout from air pollution contaminating the water supply. Back in those days coal and wood were the principal heating fuels and the air was black with soot.

  6. The red scare? I hardly think so. Coal and wood being primary fuels in those days? I came to Canada in 54 and while some people did use coal, the primary fuel was oil. Besides that, streetcars accounted for a good proportion of public transit and the were electric. I would think that the logical reason would be to reduce evaporation and prevent the growth of algae… Lloyd

  7. The park is now officially being threatened to be fenced off for good. See for more information about the proposed closure of this park as well as Dupuis park on the 3A reservoir of the Atwater filtration plant.

  8. Hello,

    Does anyone have a picture of the black hydrant? What kind is it? Does it look like the other old Montreal hydrants? Thanks

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