Raisin River (South Branch) and Gray's Creek Watersheds

Overview

The Raisin Region Conservation Authority (RRCA) is preparing a detailed model of the main channel and riverbanks of the South Branch of the Raisin River and Gray’s Creek. This model will enable the RRCA to prepare updated floodplain mapping along these two watercourses. Floodplain mapping is as a mandatory program for the RRCA under Ontario Regulation 686/21.

The updated flood hazard mapping (in progress) is the result of a partnership between the RRCA, the City of Cornwall, the United Counties of Stormont, Dundas and Glengarry, the Township of South Stormont, and the Township of South Glengarry. This project is funded in part by the Government of Canada, the Province of Ontario, the City of Cornwall, and the United Counties of Stormont, Dundas and Glengarry.

Field Surveys and Access

The RRCA and a field survey crew (J.D. Barnes) will be working along the South Branch of the Raisin River and Gray’s Creek in June 2026. Most of the field survey work will take place on municipal property. 

As part of this work, the RRCA mailed letters to specific landowners in April and May 2026 to request access to private property. Where access to private property has been requested and permission granted, it is the intent to only access the portion of properties that abut the watercourse. Access points will vary by location and could include the water’s edge, property lot lines, or driveways.

The field surveys will be limited to:

• surveying the watercourse and riverbank areas to determine the topography;
• surveying culverts and water crossings along the watercourse;
• making a visual assessment of the terrain for the purpose of river modelling; and,
• taking reference photographs for the purpose of evaluating water flows.

Protecting People and Property from Natural Hazards

Under the Conservation Authorities Act, the RRCA reviews development applications near water and wetlands to protect people and property from natural hazards such as flooding and erosion. Flood hazard maps are essential components of these reviews, and this current study will provide up-to-date information on the flood hazard in the area along the South Branch of the Raisin River and Gray’s Creek. Flood hazard maps also help inform municipal official plans and zoning schedules.

For more information

Please contact the RRCA at info@rrca.on.ca or (613) 938-3611.

The views expressed here are those of the RRCA and do not necessarily reflect those of the above funders.