Montréal bylaw: Prevent illicit stormwater discharge

Utilities and Infrastructure Quebec 3 Minutes Read · published February 11, 2026 Flag of Quebec

Montréal, Quebec property owners must prevent illicit discharges of stormwater to protect public sewers, waterways and neighbourhoods. This guide explains applicable city rules, who enforces them, steps to comply, how to report suspected discharges and practical site controls you can apply on your property.

What is an illicit stormwater discharge?

An illicit discharge is any release of non-stormwater or uncontrolled stormwater to the municipal drainage system, street, ditch or watercourse that is not authorised by a permit or municipal connection rule.

How to prevent illicit discharges

  • Inspect gutters, downspouts and connections at least twice a year and after major storms.
  • Keep permits and connection drawings on file when altering roof drainage or hardscape.
  • Install oil traps or separators for vehicle service areas and ensure regular maintenance.
  • Schedule regular sweeping of paved areas to reduce sediment and contaminants entering drains.
  • Document maintenance and any inspections to demonstrate due diligence.
Keep a dated photo record of drainage work and maintenance to support a defence if enforcement arises.

Penalties & Enforcement

Municipal enforcement in Montréal is carried out under the citys regulatory framework and by-law enforcement services. Specific fines, escalation tables and some sanction details are set in the applicable municipal regulations or borough by-laws; where amounts or ranges are not published on the cited pages this text notes that explicitly and points to the enforcing offices and complaint routes.

  • Fine amounts: not specified on the cited page; see the citys by-law repository for the controlling regulation.Voir le règlement[1]
  • Escalation: first, repeat and continuing offences are subject to progressive enforcement, but exact ranges and daily continuing fine formulas are not specified on the cited page.
  • Non-monetary sanctions: inspectors can issue orders to stop an activity, require corrective works, and may refer matters to court; seizure or injunctions may be available under municipal law.
  • Enforcer and complaints: By-law Enforcement/Service de lenvironnement receive reports and inspect alleged illicit discharges; file complaints through the citys official environmental complaint form.File a complaint[2]
  • Appeals and review: appeal routes are set out in the applicable by-law or administrative decision notices; time limits for appeals are set in those instruments and are not specified on the cited page.
If an inspector issues an order act promptly and document all remediation steps.

Applications & Forms

Requirements vary by project. The city publishes permit and by-law application pages for drainage, tie-ins and construction. If no specific form applies for a minor correction, the city may accept written proof of correction; exact form numbers and fees are not specified on the cited by-law repository page.

Common violations

  • Directly connecting wash water, effluent or contaminated runoff to storm drains without authorization.
  • Illegal rerouting of downspouts to public right-of-way or unapproved outlets.
  • Failure to maintain oil separators or containment for high-risk areas.

Action steps for property owners

  • Inspect and record current drainage points and connections.
  • Obtain required permits before altering drainage; consult municipal permits office.
  • Schedule regular maintenance and keep receipts and service reports.
  • Report suspected illicit discharges promptly using the official complaint page.

FAQ

Who inspects and enforces illicit stormwater discharges?
The City of Montréals by-law enforcement and environmental services inspect complaints and enforce municipal regulations.
What penalties will I face for an illicit discharge?
Monetary fines and orders can apply; specific fine amounts are not specified on the citys by-law repository and vary by regulation and offence.
How do I report a suspected illicit discharge?
Use the citys official environmental complaint page to submit a report and request an inspection.

How-To

  1. Map all roof, surface and subsurface drains on your property and photograph outlets.
  2. Check municipal by-laws for required permits before modifying connections; get written approval if needed.
  3. Install appropriate controls such as sediment traps, oil separators or infiltration features where required.
  4. Document maintenance and corrective actions and keep records for at least two years.
  5. If you discover or witness an illicit discharge, report it immediately through the official complaint page.

Key Takeaways

  • Preventive maintenance and documentation reduce enforcement risk.
  • Obtain permits before altering drainage systems.
  • Report illicit discharges using the citys official complaint route promptly.

Help and Support / Resources

  1. [1] City of MontrE9al - RE9glements (by-law repository)
  2. [2] City of MontrE9al - File an environmental complaint

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