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Contaminated Sites

Contaminated sites are properties that have become contaminated either in the soil or the groundwater under the land. Learn about contaminated sites in Halton Region.

Contaminated sites are properties that through past usage have become contaminated either in the soil or the groundwater beneath the land. Different kinds of properties - industrial, commercial, institutional and residential - can become contaminated.

Contamination can occur from a number of different substances including:

  • Petroleum hydrocarbons
  • PCBs
  • Metals
  • Oils


In some cases, contaminated sites become under-used or abandoned. These sites are known as brownfields. The Ontario Ministry of Environment defines a brownfield (external link) as "lands on which industrial or commercial activity took place in the past and that may need to be cleaned up before they can be redeveloped."

In 2004, provincial regulations came into effect that detailed requirements of site assessments and clean-up for property owners interested in restoring and redeveloping brownfields. These regulations are known as the Record of Site Condition (external link) (O. Reg. 153/04).

Halton's Protocol

It is the Region's responsibility to ensure that potentially contaminated sites are assessed properly and cleaned up before development can occur. Development applications may only be considered for approval when the site meets Provincial Guidelines and Regional standards for soil and groundwater quality.

In March 2022, Halton updated its Protocol for Reviewing Development Applications with Respect to Contaminated or Potentially Contaminated Sites (PDF file). The Protocol outlines the steps that must be taken and the conditions that must be met by property owners when submitting a development application.

At a minimum the applicant must submit an Environmental Site Screening Questionnaire. Regional staff thoroughly reviews each application, using a checklist, to ensure accuracy and completeness.

As required by the Protocol, we will only accept ESA Report done in compliance with O. Reg. 153/04.

Environmental source information search

Halton Region offers a service to help applicants to complete Environmental Site Assessments (ESAs) for a small fee. This service includes a thorough records investigation of Halton Region's Environmental Source Information Database (Environmental Protection GIS Database) to identify potentially contaminated sites in the region.

Download Environmental Source Information Search (Fees & Waiver Form) (PDF file) for more information and to fill out the waiver form.