On this page


Much of the following Information was provided by the Ontario Ministry of Natural Resources

Wetlands are described as lands that are seasonally or permanently flooded by shallow water as well as lands where the water table is close to the surface; in either case the presence of abundant water has caused the formation of waterlogged (hydric) soils and has favoured the dominance of water-loving (hydrophytic) or water-loving plants. The Province identifies wetlands based on the current state of the land regardless of the cause. Short-term inundation of land due to annual beaver activity or poor drainage does not create a wetland. However, if these conditions persist over the long-term (five to15 years) wetland vegetation and soils could become established and lead to the identification of these lands as wetland.

The Ministry of Natural Resources recently estimated (in 2008) that there are 51,000 hectares of wetland in the City of Ottawa. This represents approximately 18 per cent of the City’s total land mass. As of 2008, only 21,000 hectares of the City’s wetlands had been evaluated using the Ontario Wetland Evaluation System.

Four major types of wetlands are recognized in Ontario


Marshes are wetlands that are periodically or permanently flooded with water. Marsh vegetation typically consists of non-woody plants such as cattails, rushes, reeds, grasses and sedges. In open water marshes, floating and submerged plants such as water lilies and pondweeds can be found.


Swamps are wooded wetlands that are often flooded for a portion of the year, but appear quite dry during other times of the years. Swamp vegetation is dominated by trees, including both coniferous and/or deciduous species, and tall shrubs such as willows, dogwood and alder. Common throughout Ontario, swamps are remarkably diverse, exhibiting a wide array of vegetation, age and ecological settings.

Wetland with child


Bogs are peat-filled depressions that receive their water and nutrients from rainfall. Peat consists of partially decomposed plants. Bogs are extremely low in mineral nutrients and tend to be strongly acidic. They are typically covered with a carpet of Sphagnum mosses. Bogs can take several years to form and are extremely rare in the southern part of the province, through common through Northern Ontario.


Fens, like bogs are peatlands – that is, wetlands that accumulate peat. They are located in areas where groundwater discharges to the surface. Fens are typically more nutrient-rich than bogs, and the water is less acidic. While fairly rare in Southern Ontario, fens are quite common in Northern Ontario.

Why are wetlands important?

In addition to serving as an important component of healthy, functional ecosystem, wetlands provide a variety of ecological services that benefit humans. These include:

  • Improvement of water quality
  • Reduction of flood damage
  • Reduction of erosion
  • Groundwater recharge and discharge
  • Provision of habitat for fish and wildlife
  • Recreation and tourism (e.g. fishing, hunting, nature enjoyment etc.)
  • Sustainable wetland products (e.g. wild rice, cranberries, baitfish etc.)
  • Retention of carbon to help slow the release of greenhouse gases

The City recognizes the importance of wetlands, and supports the conservation of wetlands and their functions, through the policies in our Official Plan. Wetlands that have been identified by the Ministry of Natural Resources as being provincially significant (under the Ontario Wetland Evaluation System) are designated in the Official Plan as Significant Wetlands, and are subject to land use restrictions. Non-significant wetlands may be included within other environmental land use designations, or may be considered part of the City’s natural heritage system in the case of wetlands found in association with significant woodlands. 

For more information about wetlands, refer to the Ministry of Natural Resources website.

Frequently asked questions

Significant Wetlands

While all wetlands provide ecological services, some wetlands provide particularly valuable contributions based on a variety of physical, biological and social factors including size, location, diversity, hydrology, educational and/or recreational usage, and habitat for species at risk. The Ontario Ministry of Natural Resources has developed a systematic process for the classification and evaluation of wetlands in order to identify which wetlands provide sufficiently valuable services to be considered provincially significant. Significant wetlands are protected from development and site alteration under provincial planning policies.
The Province provides an exemption from property taxes on lands identified as significant wetlands (or other provincially significant natural features). Landowners who commit to preserving the wetland in its natural state can apply for this exemption on an annual basis under the Conservation Lands Tax Incentive Program.

How significant wetlands are identified

The Ontario Wetland Evaluation System (OWES) is used to assess wetlands to determine whether or not they are provincially significant based on their biological, social and hydrological functions. The OWES was developed by the Ministry of Natural Resources, and all wetland evaluations must be reviewed and approved by MNR staff. However, the Ministry typically does not conduct the actual evaluations itself. Qualified consultants, other agency staff and even private citizens trained in the application of the OWES carry out the majority of wetland evaluations.
The OWES methodology combines field investigations with “desktop” research, including aerial photo interpretation, review of available topographic and other mapping, and consultation with local stakeholders and interest groups. Ideally, field investigations include multiple site visits at different times of the year, to observe conditions in the spring, summer and fall. This approach yields a greater understanding of biological and hydrological components in particular. In cases where access to the site is limited, the evaluation may be based primarily on aerial photography and available background information, with field observations from roads and other public property. The completed evaluation is then submitted to the MNR for review and approval. The MNR maintains files on all evaluated wetlands, which are subject to revision as new information becomes available regarding changes in the wetland’s boundaries or its functions.

Most of the significant wetlands designated in Ottawa’s Official Plan were mapped in the mid-1990s. Since then, advances in technology and aerial photography have improved our ability to identify and map significant wetlands. The MNR provided updated wetland mapping to the City in 2008 as part of the Official Plan Review process that occurs every five years. Other changes have been identified subsequently through site-specific studies and re-evaluations based on new information.

If you want to challenge the MNR-approved mapping of a Significant Wetland, you will need to discuss your property with the MNR. You may need to have a qualified wetland evaluator visit your property and provide you with his or her opinion. The MNR may also want to visit your property. Please note: If the MNR finds that the wetland is larger than mapped at present, the boundary will be adjusted accordingly.

When new significant wetlands are identified, or the boundaries of previously evaluated significant wetlands change, the City will initiate an Official Plan Amendment and a Zoning By-law Amendment to accurately reflect the new wetland mapping as approved by the MNR. Affected property owners will be notified of the proposed change, and public notices will be posted as part of the amendment process. If you object to the proposed designation of a significant wetland on your property, then you must submit your comments to the City prior to the adoption of the amendment by Council. Your objection can be submitted in writing to the City’s planning staff, or you can make an oral submission by speaking at the Committee meeting where the amendment is being discussed. The appropriate staff contact and the date of the Committee meeting will be included in the public notice of the proposed amendment. If you feel your objections have not been satisfactorily addressed, then you can appeal Council’s decision to the Ontario Municipal Board.

Please note: If a person or public body does not make oral submissions at a public meeting, or make written submissions to the City of Ottawa before the proposed by-law is passed, the person or public body may not be added as a party to the hearing of an appeal before the Ontario Municipal Board unless, in the opinion of the Board, there are reasonable grounds to do so.

What the Significant Wetlands designation allows

Under the City’s policies in Section 3.2.1 of the Official Plan, a single house, accessory buildings, agriculture and forestry are permitted on existing lots within lands designated as Significant Wetlands. No new lots or site alteration such as grading or filling are permitted. If development or site alteration is proposed on land within 120 metres of the wetland, an Environmental Impact Statement is needed to show that the development will have no negative effect on the wetland, in keeping with the provincial policy statement.

Lands designated as Significant Wetlands are typically zoned “EP3” in the zoning by-law, which permits a single house as well as a home-based business and accessory structures plus agriculture and forestry operations. New lot creation through severance and subdivision is not permitted. Homeowners who want to undertake construction projects, including renovations, must follow standard procedures for building permits and septic permits.

In addition to these municipal regulations, the conservation authorities also regulate development or interference within any Significant Wetland and its adjacent lands (120 metres from the edge of the wetland). The same authority also extends to hazard lands associated with rivers, lakes and streams, floodplains, ravines and steep slopes. Working under Section 28 of the Conservation Authorities Act, the three conservation authorities in Ottawa administer the Development, Interference with Wetlands and Alterations to Shorelines and Watercourses Regulations, meaning that permission may be required from the conservation authority to undertake certain activities including the placing of fill, construction of a building or addition or installation of a new septic system. The conservation authority should be contacted to clarify the need for permission for any work within 120 metres of a Significant Wetland. Their information is provided on the contacts page.

Farming and significant wetlands

Ongoing farming activities are not affected by the wetland status of a property. For example, pasturing, cropping, switching between pasturing and cropping, fertilizing, spreading manure and application of herbicides are not affected. However, the conservation authority should be consulted on activities such as clear-cutting, drainage changes, or depositing large amounts of fill that potentially change the grade of the wetland or alter its hydrology. Periodically soaked or wet land used for agricultural purposes, that no longer exhibits wetland characteristics, should not be included in the mapping of a significant wetland.

Tree cutting and significant wetlands

The conservation authorities under their regulations do not generally become involved in the limited cutting of trees for firewood or other personal use. More extensive tree clearing or removal would, however, require permission to ensure that the activity would not adversely affect the wetland or its functions. A sustainable tree-cutting plan is likely to be a basis for any consideration of extensive tree clearing. The conservation authority should be consulted on the need for permission.
The City of Ottawa only regulates tree cutting on private lands in the urban area, and in specific adjacent rural areas recommended by staff for inclusion within the urban boundary, including a small area in the east end along the Ottawa River, between the urban boundary and Ted Kelly Lane. These areas are shown on Schedules C through H of the Urban Tree Conservation By-law (By-law 2009-200). Most privately-owned significant wetlands are located outside the area regulated by this by-law.

Contacts and resources

How can I get additional information?

  • Contact the Ministry of Natural Resources and Forestry (MNRF) directly
  • You can view the MNRF’s files on the evaluated wetlands at the Kemptville District MNRF office
  • Contact your Conservation Authority to better understand regulatory requirements
  • Information and updates regarding wetlands are available on the City’s website at ottawa.ca/wetlands
  • Refer to section 3.2.1 of the City's Official Plan for policies affecting land use in significant wetlands

Who can I contact about the evaluation of wetlands?

If you would like to discuss the evaluation of the wetland within or near your property, you may contact:

Ministry of Natural Resources and Forestry
Scott Smithers
Management Biologist, Kemptville District Office
Postal Bag 2002
10 Campus Dr.
Kemptville, ON
K0G 1J0
E-mail: Scott.Smithers@ontario.ca
Ministry of Natural Resources and Forestry

You can also arrange to visit the Ministry office in Kemptville to view its files on any wetland in the City.

Who can I contact at the Conservation Authority (CA)?

If you would like more information on the Conservation Authorities’ regulations affecting provincially-significant wetlands and the need for the CA’s permission, you may contact:

Mississippi Valley Conservation
Matt Craig
Manager of Planning and Regulations
Mississippi Valley Conservation Authority
10970 Highway 7
Carleton Place, ON K7C 3P1
Phone - 613-253-0006 ext. 226
E-mail: mcraig@mvc.on.ca

Rideau Valley Conservation Authority
Resource Specialist
3889 Rideau Valley Drive
Manotick ON K4M 1A5
613- 692-3571 ext. 1193 or 1132
E-mail: development@rvca.ca

South Nation Conservation
Mathieu Leblanc
Team Lead, Planning
1-877-984-2948 ext. 303
E-mail: mleblanc@nation.on.ca

Who can I talk to at the City of Ottawa?

If you would like to talk to a City planner generally about how this change affects how you can use your property, please contact a Development Information Officer by calling 3-1-1 or by visiting a Client Service Centre.
If you would like to discuss the process for adding the new wetlands to the Official Plan or any other matters, please contact:

Nicholas Stow
Planner III
City of Ottawa
110 Laurier Avenue West, 4th floor
Ottawa K1P 1J1
E-mail: nick.stow@ottawa.ca
613-580-2424 ext. 13000
Fax: 613-580-2459