On paper, a Mississauga data centre is a warehouse. That borrowed label is why the city passed By-law 0143-2026 on September 16, 2026, prohibiting the use on every lot it governs. It took effect on passing and runs one year unless the study finishes first, and the one rezoning application in the system was answered with a freeze on the entire category.
An interim control by-law is a Planning Act tool: it lets a council stop a defined use inside a defined area while it studies what its rules should say. Mississauga set the area at the whole city and the use at any Major Digital Infrastructure Facility of 10 megawatts or more, counted per lot.
The short answer. No new data centre of 10 megawatts or more can proceed in Mississauga, and no existing warehouse or science and technology facility can convert or expand into one at that size. Facilities already operating legally may keep operating; anything under the 10 megawatt line sits outside it. The freeze lasts one year, or until the land use study finishes to council’s satisfaction; council may extend it to two years in total.
Nothing in the by-law rules on the one application that forced the question.
- What exactly does By-law 0143-2026 prohibit?
- Why did the freeze arrive before the rules it waits for?
- Is one year of stillness protection, or is it a signal?
- What should an operator planning in Ontario record from this date?
What exactly does By-law 0143-2026 prohibit?
The prohibition is written in land rather than in projects; its Schedule A map covers all lands in the city. The line is a meter reading: computer systems, servers and their supporting components on one lot, storing or processing digital information, peaking at 10 megawatts or more in total. The count is taken per lot, so splitting one facility across neighbouring buildings does not shrink it. Section 3 closes another door: a facility meeting the definition cannot be read as any other permitted use.
The conversion clause carries the sharpest edge in the document: it reaches buildings already standing in the city’s industrial parks. An existing warehouse, distribution facility or science and technology facility may not convert or enlarge into one at that threshold during the freeze.
Why did the freeze arrive before the rules it waits for?
Mississauga’s own release states the problem in its background section, in flat language. Neither of the city’s rulebooks names the use. The Official Plan files it as warehousing, distribution and wholesaling; the zoning by-law files it as a warehouse and distribution use, or a science and technology facility. Neither document was written for a building whose defining feature is the power it draws, the water it consumes and the heat it sheds. Several data centres already operate or hold permission inside the city under those borrowed categories, approved under rules that never named the use.
The Meadowvale rezoning application forced the question into the open: a council cannot weigh a use its own policies do not describe. Staff had briefed the general committee on the province’s draft Data Centre Playbook one week earlier, on September 9, and the provincial guidance was still guidance rather than law. Council therefore reached for the one instrument that requires no finished policy behind it. It used that instrument at the full scale the Planning Act permits: one by-law for the entire municipality. That sequence is the accountability record in this file: the freeze is dated September 16, and every rule it waits for carries a later date or no date at all. Ottawa had landed on the same wall thirteen days earlier, when it published expectations and kept none of the switches. Ottawa Set Five Expectations for Data Centres. The Switches Sit Elsewhere.
Is one year of stillness protection, or is it a signal?
Shield or flare? The by-law reads honestly as each, and the document supports both readings. The first treats the freeze as protection, because the study it orders is broad and overdue. The by-law directs staff to spend the year on the questions the use itself raises: the power these buildings draw, the water they consume, the heat they shed, the noise they carry and the air they emit. A city that runs that study properly hands its next applicant a rulebook instead of an argument.
The second reading treats the freeze as a signal, because capital reads a one-year stop as a position rather than a pause. The by-law covers every lot in the city, catches conversions nobody has proposed yet, and runs at the pleasure of the council that passed it. A proponent comparing Ontario municipalities this fall will register Mississauga as the city that answered its first serious application by prohibiting the category. Five days after this vote, two more Ontario councils gave two different answers to the same question. Milton Voted to Study Data Centres. Sault Ste. Marie Voted to Stop Them.
The freeze protects the city only while the study is actually moving, because the instrument expires on its own date whether the work is finished or not. Time is the entire substance of what council bought on September 16; without a finished study, the pause becomes the policy by default. The signal and the protection are the same year, and the study calendar is the only thing that decides which name the year earns.
What should an operator planning in Ontario record from this date?
Record the threshold first, because 10 megawatts is now a municipal number with a by-law behind it, and thresholds travel between council chambers. Record the scope second, because the conversion clause means an existing industrial building in Mississauga is no longer a quiet route around the freeze. Record the sequence third, because the municipal clock now runs ahead of the unfinished provincial playbook, and it is the clock that binds.
The city promises an interim report on scope and timeline before the end of this year, with public engagement through the review. An operator with power-hungry plans anywhere in Ontario should read that report on the day it lands. It will show how a city-wide freeze intends to spend its year.
Every other date in this file can move: studies slip, reports defer, and councils extend their own instruments. One date sits outside that traffic, fixed by the text of the by-law itself. By-law 0143-2026 expires on September 16, 2027, one year from the day it passed. It ends earlier only if the study finishes to council’s satisfaction, and council may stretch the term toward its two-year limit. Anyone who wants a different answer in Mississauga has that date, and only that date, to plan around.
Recap. On September 16, 2026, Mississauga passed By-law 0143-2026 and froze every new data centre at 10 megawatts or more, city-wide, for one year. One rezoning application stood in the system; council answered it with a category freeze, not a decision on the file. The freeze exists because the city’s plan and zoning by-law classify data centres as warehousing, a category written before the use had a name. The study now under way decides whether the year bought protection or merely sent a signal.
Follow the whole Ontario file as it moves: Canada’s data centre map: what is built, what is blocked, what is waiting.
