Archaeological assessments

Before approving a land development project regulated by legislation, the approval authority for the project requires an archaeological assessment of all lands that are part of the project. Assessments are required when the land is known to have an archaeological site on it, or has the potential to have archaeological resources.

Archaeological assessments must be carried out by consultant archaeologists. We publish a list of all archaeologists licensed in Ontario.

Provincial criteria for determining areas of archaeological potential

Areas of archaeological potential are areas of a property that could contain archaeological resources.

See the ministry checklist (PDF) for determining archaeological potential. We developed it for non-specialists, such as approval authorities and development proponents, to help them identify areas of archaeological potential on lands being developed.

What triggers an archaeological assessment?

Housing subdivisions and other land development projects. The approval authority — under the Planning Act, usually the municipality where the new subdivision is located — will include the requirement for an archaeological assessment as one of the conditions for development approval to ensure that the development proponent meets their legal obligations under the Ontario Heritage Act.

Public development projects such as power projects, highway or road construction, or sewer construction require an archaeological assessment under the Environmental Assessment Act directly or through a Class Environmental Assessment. In many cases, an environmental assessment determines the need for an archaeological assessment, and it is completed as part of the overall environmental assessment process.

Renewable energy projects such as wind farms and solar farms may also require archaeological assessments in order to obtain a Renewable Energy Approval from the Ministry of the Environment.

Quarrying, forest harvesting, installing pipelines and other land use activities also require archaeological assessments.

Lands owned by the Province. The Ontario government, through Infrastructure Ontario, has its own environmental assessment process, including archaeological assessment, for its properties.

What happens during an archaeological assessment?

During the first three stages, the consultant archaeologist will:

  • Discover any archaeological resources on the lands that are being developed;
  • Determine the degree of cultural heritage value of any archaeological resources found on the property;
  • Recommend the most appropriate strategies for conserving archaeological sites prior to land development activities.

The consultant archaeologist will recommend a fourth stage — mitigation of development impacts — where warranted.

Not all stages will be necessary for all projects.

Stage 1: background study and property inspection

The consultant archaeologist determines whether there is potential for archaeological sites on the property. He or she reviews geographic, land use and historical information for the property and the relevant surrounding area, visits the property to inspect its current condition and contacts this ministry to find out whether or not there are any known archaeological sites on or near the property. A Stage 2 assessment is required when the consultant archaeologist identifies areas of archaeological potential.

Stage 2: property assessment

The consultant archaeologist surveys the land to identify any archaeological resources on the property being developed. For a ploughed field, he or she will walk back and forth over it looking for artifacts on the surface. In forests, overgrown pasture areas or any other places that cannot be ploughed, he or she will dig parallel rows of small holes, called test pits, down to sterile subsoil at regular intervals and sift the soil to look for artifacts. He or she may use other strategies if properties are paved, covered in fill or have deeply buried former topsoils (such as floodplains or former sand dunes). The consultant archaeologist will help determine whether any archaeological resources found are of sufficient cultural heritage value or interest to require Stage 3 assessment.

Stage 3: site-specific assessment

This stage is for all archaeological sites that may be of cultural heritage value or interest. The consultant archaeologist accurately determines the size of the archaeological site, evaluates its cultural heritage value or interest and, where necessary, makes recommendations for Stage 4 mitigation strategies. To this end, he or she conducts further background research and fieldwork that expands the information gathered in Stage 2. He or she maps the spatial limits of a site and acquires further information about the site's characteristics by excavating one-metre by one-metre square test units across the site. Based on circumstances, some sites, for example ones that have been paved or are deeply buried, may require specialized methods of assessment.

Stage 4: mitigation of development impacts

This stage involves implementing conservation strategies for archaeological sites that are of cultural heritage value or interest. Determining the best approach for conserving the site may include reviewing possible strategies with the development proponent, the municipality or other approval authority, Aboriginal communities, and other heritage stakeholders.

Conserving archaeological sites that have cultural heritage value or interest does not mean stopping development. Conservation can involve putting long-term protection measures in place around an archaeological site to protect it intact. The site is then avoided while development proceeds around it. This is called protection ‘in situ’ and is always the preferred option for mitigation of development impacts to a site. If protection is not viable, mitigation can involve documenting and removing an archaeological site, through excavation, before development takes place.

Long-term avoidance and protection

Unless long-term protection measures are in place, an archaeological site is not considered truly protected. The consultant archaeologist will provide the development proponent with recommendations for an avoidance and long-term protection strategy. These can include protection measures such as restrictive covenants on title, zoning by-law amendments or the transfer of land ownership to a municipality or other public land-holding body. Ontario's Heritage Toolkit outlines these and other long-term protection measures.


If circumstances do not allow a site to be protected in situ, the site may be excavated before construction begins. The purpose of excavation is to document the site through measurements, maps, drawings and photographs and to remove artifacts.

Report to the ministry

After completing an archaeological assessment, the consultant archaeologist develops and sends a report to this ministry. We review the report to ensure that:

  • The licensed archaeologist met the terms and conditions of his or her licence, including the ministry's requirements for fieldwork and reporting.
  • Any archaeological sites found were properly conserved.


For more information contact:

Ministry of Tourism, Culture and Sport
Archaeology Programs Unit