Part C: Renewable energy natural heritage assessments

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C1. Overview of the natural heritage assessment

The natural heritage assessment includes 3 sequential stages that are required under the Regulation:

a records review to determine if natural features, provincial parks or conservation reserves may exist in the vicinity of the project location
a site investigation of land and water within a specified distance of the project location to determine if additional natural features exist and to confirm the presence and location of natural features, provincial parks or conservation reserves identified in the records review
an evaluation of significance of any identified natural features

A report is required to summarize each of these 3 stages. This part of the Guide describes each stage of an NHA.

Development prohibitions and exceptions to prohibitions related to natural features are included in sections 37, 38, 41, and 43 of the Regulation.

In addition, an EIS (go to part D of this Guide) and/or an EEMP (go to part E of this Guide) may also be required.

C2. Records review

The records review is the initial stage of an NHA and is required under section 24 of the Regulation. The purpose of the records review is for the applicant to gather information about the area in which a project location is proposed, identify natural features, provincial parks or conservation reserves, and make preliminary determinations about site feasibility.

Records reviews must be completed by qualified persons (go to part B of this Guide).

A records review involves a search and analysis of records that relate to natural features maintained by specified organizations to determine if the project location is in or within 50 or 120 metres, as the case may be, of a natural feature. Applicants must undertake a records review and prepare a records review Report as described in section 25 of the Regulation.

Table C1 of this Guide contains procedures for conducting a records review, for identifying natural features and for determining the boundaries of natural features.

While these records are to be searched and analyzed as part of a records review, this information can also inform other aspects of the NHA. In locations where little information about natural features is available, applicants can use the records review to assemble general information about the project location and potential natural features, before progressing to the site investigation stage.

As part of contacting any planning authorities (for example, municipality, conservation authority) during a records review, applicants must determine if an ELC assessment for the area has already been conducted and if any ELC mapping for the area is available.

Applicants should also consider other available information and resources available for the area where the project is proposed to be located. For example, applicants can refer to the following for additional sources of information:

data sources provided in the SWHTG and the SWHTG ecoregional criteria schedules
sources of information listed in appendix E2 related to birds and bats
sources of information described in the OWES manuals

Indigenous knowledge, where voluntarily shared, may be considered to support natural heritage assessments.

Applicants may want to consider searching and reviewing records for an area wider than that required by regulation to accommodate any potential changes to project design or layout that may occur later in the project planning stages.

Wildlife habitat data collected during the records review may identify critical habitat components (for example, potential hibernacula, raptor nest) which should be noted as points on a map. While these critical habitat components may originate further than 120 metres from the project location, they will often have associated candidate or confirmed significant wildlife habitat that can extend well beyond the area of the critical habitat component itself.

Table C1: records review requirements related to specific natural features
Natural feature	Records review requirements
Wetlands	Geospatial information about provincially significant wetlands across Ontario must be accessed through Ontario GeoHub. Where Ontario GeoHub identifies a wetland that has already been evaluated as provincially significant, the applicant may need to access paper or digital wetland evaluation data records to inform other requirements (for example, for an environmental impact study). Wetland evaluation data records may be available from: MNR work centre offices (for wetland evaluations completed prior to 2023 and for wetland evaluations completed for wetlands located on public (Crown) lands) Local municipal offices (official plans, wetland evaluations completed after 2023) within organized municipal boundaries Ontario GeoHub must also be searched for geospatial information about wetlands that may be present at or in the vicinity of the project location which may not yet have been evaluated for significance. Wetlands in a provincial plan area can include any wetlands identified through the following processes: wetlands evaluated and identified in accordance with the Ontario wetland evaluation system (OWES) wetlands identified in mapping provided by the province or a conservation authority wetlands identified in a natural heritage evaluation or a hydrological evaluation required under a provincial plan Where all or part of a project location is proposed within a provincial plan area, municipal records (for example, mapping to support official plans) must be searched for information about wetlands. Where all or part of a project location is proposed within the jurisdiction of a conservation authority, the conservation authority must be contacted to identify any wetlands mapped within the area of their jurisdiction.
Woodlands in Ecoregions 6E and 7E	Municipal records (for example, as part of official plans) must be searched to identify any significant woodlands that may have already been identified by the municipality.
Areas of natural and scientific interest (ANSIs)	Ontario GeoHub must be searched for geospatial information about ANSIs. Boundaries and level of significance (that is, provincially significant or regionally significant) of each confirmed ANSI are available in the ANSI data class. Where Ontario GeoHub identifies a provincially significant ANSI, the applicant may need to access paper or digital records (that is, site district reports, Ecodistrict reports or ANSI checksheets/checklists) to inform other requirements (for example, for an environmental impact study). When needed, such reports or documents must be requested from MNR work centre offices. When searching ANSI records, all provincially significant ANSIs must be identified and included in the records review report. Also, in the context of provincial plan areas, regionally significant life science ANSIs must be included in the records review. Information related to regionally significant ANSIs located outside of provincial plan areas and candidate ANSIs must also be collected, and noted in the records review Report, as this information may aid in identifying other natural features (for example, wetlands, woodlands, wildlife habitat) at or in the vicinity of the project location.
Wildlife habitat (general)	Information about any known critical wildlife habitat components and any associated candidate or confirmed SWH that may extend to or within 120 metres of the project location must be searched and analyzed. Ontario GeoHub must be searched for information about wildlife habitat at or within the vicinity of the project location. For example, a search of Ontario GeoHub for the term ‘wildlife’ (and other related terms) will return various data sets and documents that may support the identification of candidate SWH). Municipal records (for example, as part of official plan) must be searched to identify any SWH that may have already been identified by the municipality.
Wildlife habitat for birds and bats	During the records review, records must be searched to identify and collect all available bird and bat information related to the project location and its vicinity. This will include information on: the species present (or likely present) and their relevant life cycle/history characteristics any confirmed SWH features associated with candidate SWH (for example, caves, talus, karsts, cliffs, woodlands, grasslands, wetlands, ridges) habitat types (for example, mapped ELC) important bird areas (IBAs) other relevant information (for example, potential feeding, breeding, roosting/nesting, stopover, staging and migration areas not already included in IBAs) A list of information sources specific to birds and bats and their habitats that applicants may find helpful are provided in appendix E2 of this Guide.
Sand barrens, savannahs, tallgrass prairies and alvars in provincial plan areas	Ontario GeoHub must be searched for information on any sand barrens, savannahs, tallgrass prairies and alvars that may have already been identified and mapped by the province. Open data can be accessed by searching for “provincially tracked species (1 km grid)” or “SOLRIS (Southern Ontario land resource information system (SOLRIS) 3.0) in Ontario GeoHub. Precise boundaries are available through the natural heritage information centre. To request access to them follow the instructions for restricted natural resources datasets on natural resources data access requests.
Provincial parks or conservation reserves	Go to part F of this Guide

Records review report

Consistent with the Regulation, a report must be prepared setting out a summary of the records searched and the results of the analysis conducted.

Further to subsection 25 (3) of the Regulation, the following information must be included in the report:

description of all records reviewed. At a minimum, include the title of the record and a description of information contained in the record
source and ownership of the record
date(s) the records were searched, collected or accessed
list of all organizations contacted

C3. Site investigation

The site investigation is the second stage of an NHA and is required under section 24 of the Regulation. The purpose of the site investigation is to confirm the presence and boundaries of natural features and provincial parks or conservation reserves within the site investigation area for the project location, and identify any additional natural features not identified through the records review.

Site investigations must be conducted by qualified persons (go to part B of this Guide).

Applicants must undertake a site investigation and prepare a site investigation report in accordance with section 26 of the Regulation. Table C2 of this Guide describes additional requirements for conducting site investigations for each natural feature.

Applicants may wish to expand the site investigation area to an area large enough to accommodate any potential changes to project design or layout that may occur later in the project planning stages.

Applicants must conduct an ELC assessment as a component of a site investigation or alternative investigation. The ELC assessment can also be used as the basis for the creation of the site investigation map.

Classifying lands to the vegetation type level provides the finest scale of detail and is required for identification of rare plant communities. The ELC assessment must include an interpretation or orthorectified aerial or satellite imagery to delineate ELC units where possible. Verification of this interpretation to confirm accuracy must be undertaken during the site investigation. Where it is not reasonable to visit the site (go to section C3.1 of this Guide), applicants are encouraged to use geospatial tools and platforms (such as Geographic Information System software) and/or analyze orthorectified aerial or satellite imagery to complete an ELC assessment as part of an alternative investigation.

Fieldwork to support the site investigation must be conducted at times which are seasonally appropriate for the natural features being studied.

Prior to conducting the site investigation, it may be helpful to have an understanding of the following so that the appropriate and relevant information can be collected:

criteria for evaluating the significance of natural features (go to section C4 of this Guide)
alternative approaches to evaluating for significance (go to section C4.1 of this Guide)
additional fieldwork which may be necessary to prepare an EIS report (go to part D of this Guide)

Applicants should consider retaining supporting data files (for example, shapefiles) related to the site investigation in case they are needed to support the application process.

Table C2: site investigation requirements related to specific natural features
Natural feature	Site investigation requirements
Wetlands	Wetlands must be delineated using methods outlined in the OWES or the ELC. OWES methods to delineate wetlands must be used if the wetland must be evaluated to determine significance (go to section C4 of this Guide). ELC methods to delineate wetlands must be used where OWES methods are not used. If all or part of the project location is within the greenbelt plan area, the greenbelt technical paper must be used to further identify wetlands during the site investigation. If all or part of the project location is within the Oak Ridges moraine conservation plan area, the Oak Ridges moraine conservation plan technical paper series 1 – Identification of key natural heritage features must be used to further identify wetlands during the site investigation.
Woodlands in ecoregions 6E and 7E	Woodland boundaries must be delineated using the outer edge of the trees’ drip line. ELC methods must be used to delineate treed areas which meet the definition for “woodland” in the Regulation. If all or part of the project location is within the greenbelt plan area, the greenbelt technical paper must be used to further identify woodlands during the site investigation. If all or part of the project location is within the Oak Ridges moraine conservation plan area, the Oak Ridges moraine conservation plan technical paper series 1 – Identification of key natural heritage features must be used to further identify woodlands during the site investigation.
Wildlife habitat (general)	The site investigation must include the identification of any confirmed or candidate SWH identified through the records review. Identification and delineation of candidate SWH must be conducted using: the applicable regional ELC manual to identify and delineate ecosites (note: the southern ELC manual is to be used where identification of rare vegetation types and specialized habitats requires classification of vegetation type) SWH technical guide (provides guidance for identifying the types and extent of habitat) where available, SWH ecoregional criteria schedules (source of ELC ecosite codes, habitat criteria and information sources) When conducting the site investigation, applicants must understand that critical wildlife habitat components (for example, potential hibernacula, raptor nest) may originate further than 120 metres from the project location, however, they will often have associated candidate or confirmed SWH that can extend well beyond the area of the critical habitat component itself.
Wildlife habitat for birds and bats	All candidate bird and bat SWH must be identified and delineated within 120 metres of any part of the project location. The SWHTG and SWHTG ecoregional criteria schedules provide criteria to help in identifying candidate SWH, confirming SWH and defining an area that supports the form and function of SWH. Criteria schedules have been completed for ecoregions 3E, 5E, 6E and 7E in Ontario and provide more detailed guidance for habitats found within each ecoregion. Some examples of bird and bat SWH are provided in the list below. Other specialized SWH for birds and bats, not listed below, may also be present. The knowledge and expertise of the qualified person(s) during the wind project site assessment process (that is, records review, site investigation, evaluation of significance) is critical for identifying and evaluating the significance of bird and bat habitats. Bats: seasonal concentration areas bat hibernacula bat maternity colonies bat migratory stopover areas Birds: seasonal concentration areas colonial bird nesting sites waterfowl stopover and staging areas waterfowl nesting sites shorebird migratory stopover areas landbird migratory stopover areas raptor winter feeding and roosting areas wild turkey winter range turkey vulture summer roosting areas Rare or specialized bird habitats, including: woodland area-sensitive bird breeding habitat raptor nesting habitat osprey and bald eagle foraging and perching habitat sharp-tailed grouse lek habitat Habitat of bird species of conservation concern, including: shrub/early successional bird breeding habitat open country bird breeding habitat marsh bird breeding habitat
Sand barrens, savannahs, tallgrass prairies and alvars in provincial plan areas	The identification of sand barrens, savannahs, tallgrass prairies and alvars must be determined by using the ELC for Southern Ontario. Sand barrens, savannahs, tallgrass prairies and alvars, as defined in the greenbelt plan and the Oak Ridges moraine conservation plan (ORMCP), are comprised of the alvar community class, sand barren and tallgrass (prairies, thicket, savannahs and woodland) units of the ELC system. Given the sensitive and unique features of these natural features, qualified persons experienced in dealing with these special communities must be involved in a site investigation that might include these natural features. If all or part of the project location is within the greenbelt plan area, the greenbelt technical paper must be used to further identify these features during the site investigation. If all or part of the project location is within the Oak Ridges moraine conservation plan Area, the Oak Ridges moraine conservation plan technical paper series 1– Identification of key natural heritage features must be used to further identify these features during the site investigation.
Provincial parks or conservation reserves	Go to part F of this Guide

C3.1 Alternative investigation

Under section 26 (1.1) of the Regulation, an alternative investigation may be conducted if the applicant determines that it is not reasonable to visit a site (a part of air, land or water within the site investigation area) to conduct a site investigation. An alternative investigation must verify the accuracy of the records review report while identifying any additional natural features not identified through the records review. In the site investigation report, the applicant must provide an explanation of the rationale for making the determination that it was not reasonable to visit the site.

In most cases, an alternative investigation will be best conducted through analysis of orthorectified aerial or satellite imagery or other forms of aerial survey (for example, drones, helicopters) verified with observations, where possible, from the project location and fence line or roadside observations. The applicant may also undertake other forms of site visits to support the alternative investigation including, access via rights of way (for example, roads, unopened municipal road allowances, hydro corridors), roadside checks, water access, using binoculars in leaf-off conditions to examine the interior of a site, and other means of making direct observations.

Some examples of situations where visiting a site for the purposes of conducting a site investigation would not be reasonable, as well as information which is required to be provided in the site investigation report to support the determination are provided below. These examples are not exhaustive; however, they represent commonly encountered scenarios.

Examples of rationale for undertaking an alternative investigation include:

when access to a site is not granted by an adjacent landowner
when visiting a site is unsafe (for example, unstable soils)

Supporting information must be provided in the site investigation report to demonstrate why the alternative investigation is the only feasible approach. For example:

attaching a summary of results of requests to access site (for example, a list of landowner(s) or occupier(s)/possessor(s) of land, as applicable, contacted, number and method of contact attempts, time/date of contact, summary of communications), and copies of any written correspondence and replies should be kept on file by the applicant)
documentation confirming presence of unsafe conditions (for example, conservation authority records and official plan schedules indicating hazard area)
visual evidence depicting presence of unsafe conditions (for example, photographs)
rationale for proceeding or intending to proceed with the project despite unsafe conditions (for example, description of how the project would be constructed if site is unsafe to access)
description of efforts to overcome or mitigate unsafe conditions in order to visit the site to conduct a site investigation (for example, use of aerial survey)

In all cases, applicants must be able to provide a rationale for determining that a site is not reasonable to visit, a description of efforts to access the site, and associated documentation.

The determinations required under the Regulation continue to apply to alternative investigations, as well as specific requirements of the site investigation report. Likewise, the direction and resources identified in sections of this Guide related to natural feature specific site investigations remain relevant and should be consulted.

Site investigation report

Consistent with the Regulation, a report must be prepared containing all information specified in subsection 26 (3) of the Regulation.

When preparing a map(s), in addition to what is set out in the Regulation, the following mapping procedures must be followed:

map(s) must be at a scale appropriate to the size of the project location and surrounding natural features and be based on the most recent information available. The operational map scale standard is 1:20,000, at a minimum. A finer scale may be required where more accuracy and detail is warranted
include a unique identifier for each natural feature and reference consistently throughout the site investigation report
clearly depict all areas where an alternative investigation was conducted
where several natural features are present, include multiple maps arranged by feature type
where the project location extends over a large area, an overview map along with the operational map(s), at scales that appropriately reflect the geographic orientation of the project
indicate the distance between each natural feature and the project location directly on maps, or include a table which references the distances
illustrate the entirety of natural features on map(s), including portions which extend outside of the site investigation area
clearly identify each natural feature by type on the legend
any exported map(s) must be georeferenced

Include an additional map of the project location and surrounding area showing high-resolution aerial or satellite imagery available from the Ontario imagery program.

Applicants may also refer to the document “Map design considerations for accessibility” for recommendations on designing maps that are accessible.

C4. Evaluation of significance

With some exceptions set out in the Regulation, paragraph 3 of subsection 24(1) of the Regulation requires applicants to determine if any natural features located within the site investigation area are significant or provincially significant.

Prior to undertaking an evaluation of significance of a natural feature, applicants may wish to consider if the project could be relocated outside of the natural feature or its adjacent lands. If, after such a relocation, the project is no longer proposed to be located within a natural feature or its adjacent lands, an evaluation of significance is not required.

Previously evaluated natural features

In some instances, the significance of a natural feature can be established solely through the information obtained during the records review (for example, a previously evaluated wetland identified as provincially significant).

Where the applicant references a previous evaluation of significance, the evaluation of significance report must note this and summarize information required in the report to the best extent possible.

In cases where a natural feature within the site investigation area has previously been evaluated as significant or provincially significant, the applicant is not required to re-evaluate the feature for significance.

Criteria and procedures for undertaking an evaluation of significance

Applicants must undertake an evaluation of significance and prepare an evaluation of significance report as described in section 27 of the Regulation.

Evaluation criteria and procedures that must be used when conducting an evaluation of significance are listed in table C3 of this Guide. All criteria and procedures identified in table C3 may be amended from time to time, and where column 2 of table C3 does not refer to the most recent version of the criteria or procedure, it is to be read as referring to the most recent version.

Evaluations of significance must be completed by qualified persons (go to part B of this Guide). In conducting an evaluation of significance, subsection 27 (1) of the Regulation requires that applicants make use of any available information related to the natural feature, including all information:

obtained through the records review
obtained through the site investigation or alternative investigation
received from the public, Indigenous communities, municipalities, local road boards and local services boards, until such time as the evaluation of significance report has been prepared

For locations outside of provincial plan areas, if through evaluation, the natural feature is assessed to be not significant or not provincially significant, the feature is not subject to development prohibitions. However, applicants must document these findings in the evaluation of significance report.

As with the site investigation stage, any fieldwork associated with an evaluation of significance must be conducted at seasonally appropriate times for the natural features being studied.

Table C3: Criteria and procedures for evaluating the significance of natural features
Natural feature	Criteria / procedure to evaluate significance
Wetlands	For a wetland identified during the records review or site investigation that has not been previously evaluated for significance, applicants must use the most recent version of the Ontario wetland evaluation system southern manual (for wetlands located in ecoregions 6 and 7) or the Ontario wetland evaluation system southern manual (for wetlands located in ecoregions 2, 3, 4 and 5) to determine provincial significance. The OWES manuals are available on a website of the government of Ontario. Wetlands determined to be provincially significant by an evaluation using a previous version or edition of the OWES manuals continue to be considered to be provincially significant.
Woodlands in ecoregions 6E and 7E	For a woodland identified during the records review or site investigation that has not been previously evaluated for significance applicants must use: For woodlands outside of provincial plan areas: criteria and procedures set out in appendix C1 of this Guide For woodlands within provincial plan areas: criteria and procedures related to woodlands set out in greenbelt and Oak Ridges moraine technical papers (go to section A4 of this Guide) Woodlands that are mapped and determined to be significant by a planning authority (for example, municipality) are considered to be significant.
Wildlife habitat	The entire area of an important bird area is considered to be confirmed significant wildlife habitat. For candidate SWH identified during the records review or site investigation applicants must use the following to evaluate for significance (that is, to determine confirmed SWH): The significant wildlife habitat technical guide with the following modifications with respect to the criteria for habitat of species of conservation concern: references to “species identified as nationally endangered or threatened by COSEWIC, which are not protected under Ontario’s Endangered Species Act” are replaced with “species listed in schedule 1 under the federal Species at Risk Act” references to “species identified as provincially vulnerable based on lists of VTEEE species of Ontario” are replaced with “species included in the protected species in Ontario list under the Species Conservation Act, plus any species currently classified as special concern by the committee on the status of species at risk in Ontario (COSSARO).” Significant wildlife habitat eco-regional criteria schedules (where available) The SWH technical guide and SWH eco-regional criteria schedules are available on a website of the government of Ontario.
Areas of natural and scientific interest (ANSIs)	ANSIs are identified and confirmed as provincially significant using the “identification and confirmation procedure for areas of natural and scientific interest (2011)”. In accordance with this procedure, only MNR can determine the significance of an ANSI and thus applicants do not need to undertake evaluations of ANSIs. Note: ANSIs that have been identified but not confirmed through the accepted evaluation (confirmation) procedure are referred to as “candidate ANSIs”. For the purposes of this Guide, an ANSI is not considered provincially significant until it has been confirmed by the MNR. While “candidate ANSIs” do not need to be considered under this framework, applicants are encouraged to gather information on candidate ANSIs during the records review, as information about such candidate ANSIs could support identification of other significant natural features (for example, candidate significant wildlife habitat).
Sand barrens, savannahs, tallgrass prairies, alvars in provincial plan areas	An evaluation of significance regarding these natural features is not required if the project is located within a provincial plan area (go to subsection 27 (6) of the Regulation).

C4.1 Alternative approach to evaluation of significance

Although a full evaluation of significance is preferred, in some cases, the applicant has a choice as to whether they:

conduct an evaluation of significance according to procedures specified in table C3 of this Guide
treat the natural feature as if it were significant, complete an assessment (where required) and complete an EIS

Note that the assessment under approach (b) will not be used to officially define the status of natural features (for example, as significant or not significant).

Table C4 of this Guide describes situations where the applicant can choose to treat a natural feature as if it were significant or provincially significant instead of completing an evaluation of significance. Where all or part of renewable energy project is proposed to be located in or within the adjacent lands of a natural feature that is treated as if it were significant, an EIS must be conducted (and, in some cases, a wetland assessment). In these cases, the evaluation of significance report for eligible natural features must note that an EIS (and a wetland assessment, if applicable) was completed instead.

table C4: Eligible situations for alternative approaches to an evaluation of significance
Eligible situation	Requirement instead of evaluation
All or part of a renewable energy project is proposed within candidate significant wildlife habitat (SWH) or its adjacent lands	Treat the candidate SWH habitat as if it were significant Gather sufficient baseline information on any identified candidate SWH to assess key habitat characteristics and ecological functions to inform preparation of the EIS Prepare an EIS report using the procedures set out in part D of this Guide
All or part of a renewable energy project is proposed: within the adjacent lands of a wetland that has not previously been evaluated for significance and the development is not proposed within the wetland itself to span a wetland, where structures would be located outside of the wetland (for example, placement of a transmission pole adjacent to edges of a wetland with a transmission line mounted between poles) within a northern wetland that has not previously been evaluated for significance	treat the wetland as if it were provincially significant conduct a wetland assessment using the procedures set out in appendix D2 of this Guide) prepare an EIS report using the procedures set out in part D of this Guide
Development proposed within a woodland (located in ecoregions 6E or 7E) or its adjacent lands, where the woodland has not been previously evaluated for significance.	treat the woodland as if it were significant gather sufficient baseline information to assess key habitat characteristics and ecological functions to inform preparation of the EIS prepare an EIS report using the procedures set out in part D of this Guide

All baseline information gathered, including information required for the wetland assessment, must be described and included in the EIS report.

Note, for wetlands, a wetland cannot be “treated as if it were significant” instead of completing an evaluation of significance if any part of the project location is proposed within a southern wetland or a coastal wetland.

Updated: May 28, 2026

Published: May 28, 2026