Things to consider: These are areas of ecological significance within a jurisdiction. By-law definitions should make reference to the municipal official plan, zoning by-law or other applicable planning document(s) where the jurisdiction’s environmentally sensitive areas are described, as the Ontario Regulation 153/04 does not provide a definition. A general definition is as follows:

“‘Environmentally Sensitive Area’ means an environmentally sensitive area, natural area, ravine, core supporting area, environmental constraint area, or other area as designated in the City's Official Plan, as amended, including as set out in Schedules "B" and "B 1" thereto, or the Regional Official Plan, as amended, used to define, describe or delineate an area of environmental importance;”1

An additional regional example includes:

“‘Environmentally Sensitive Area (ESA)’ refers to Environmentally Sensitive Areas identified in the Halton Region Environmentally Sensitive Areas Consolidation Report dated April 2005, as amended.”2

O. Reg. 153/04 does provide site condition standards for environmentally sensitive areas, which municipalities may also refer to, and are applicable if:

  1. the property is,
    1. within an area of natural significance,
    2. includes or is adjacent to an area of natural significance or part of such an area, or
    3. includes land that is within 30 metres of an area of natural significance or part of such an area;
  2. the soil at the property has a pH value as follows:
    1. for surface soil, less than 5 or greater than 9,
    2. for sub-surface soil, less than 5 or greater than 11; or
See the Definitions Page for additional terms relevant to any site alteration or fill by-law.


Things to consider: By-laws which include reference to environmentally sensitive areas generally restrict site alteration on these lands within the Prohibitions section of the site alteration by-law. Language generally indicates that site alteration is not permitted on these lands unless approved by Council/the Corporation, unless a building permit or other development agreement has been issued, or unless it is permitted by Provincial legislation. Examples of language that achieves this intent include:

“No person shall undertake, cause, permit or perform any Site Alteration within an area designated as an Area of Natural Significance or an Environmentally Sensitive Area or any similar designation under the Corporation's Official Plan unless permitted specifically by provincial legislation or regulation.”3


“Notwithstanding any other provision of this By-law, the Director shall not issue a Permit under this By-law with respect to lands in the City of Burlington defined and designated as an Environmentally Sensitive Area by the City’s Official Plan without the approval of Council.”4

By-laws can also include regulations for specific environmentally sensitive areas, as in the example below. These areas can be defined in the by-law, wherever appropriate, as in the following example:

“No person shall carry out any Site Alteration Adjacent to or within 30 metres of Wetlands, Fish Habitat, significant valley lands, significant woodlands, significant wildlife habitat, habitats of Rare and Endangered Species, Areas of Natural or Scientific Interest and permanent or intermittent streams without having been issued a Permit under this By-law by the Director of Engineering or without having obtained written permission from the Conservation Authority where applicable.”5