This site provides maps that identify roads around Mississippi Lake that are expected to flood a minimum of 30 cm during a 1:100 year flood event.  The maps were produced using 2020 LiDAR information, and updated to included more recent survey data provided to MVCA.

If you are concerned about the elevation shown for your road, MVCA will review any additional recent information that is produced by a qualified professional and is based on the Canadian Geodetic Vertical Datum CGVD28.

Background

In 2022, MVCA adopted a Watershed Plan for the Mississippi River that recommends a variety of actions to support safe and sustainable development. One recommendation was to examine roads that flooded during the 2019 flood and other roads with potentially “unsafe access”. Last year, the Mississippi Lake Association (MLA) approached MVCA to pursue an investigation of roads abutting the lake. Preliminary investigations were conducted in 2023 and results are being shared with MVCA’s Board of Directors, Emergency Services at the Township of Beckwith, Township of Drummond North Elmsley, and the Municipality of Mississippi Mills, and area residents.

Methodology

A table-top review of flood plain mapping was used to identify roads at risk of flooding during a 1:100-year flood event. MVCA did spot-check surveys in a selection of areas where information received indicated that road works may have altered the road’s vulnerability during a 1:100-year flood event. Based upon the desktop review and field spot checks, MVCA created a list of roads at risk for use by area municipalities and local road associations to prioritize the need for further surveys and road works. This work will assist municipal staff involved in emergency response during flood events.

Unsafe Access

Vehicular and pedestrian access routes are deemed unsafe if the depth of flooding during a regulatory (1:100 year) flood event is equal or greater than 30 cm along the travelled surface of the road where the water velocity does not exceed 1.0 meter/second. Under these circumstances, development of the property may be limited by MVCA to prevent loss of life and property during a flood event. Alterations can be made to a road to reduce or eliminate this risk, but must be done in consultation with MVCA and requires a permit and legal survey to verify finished grades.

Findings

Much of Mississippi Lake was developed before flood plain mapping was available and before regulations were in place to restrict development within the flood plain. Therefore, several roads and properties around the lake are subject to
seasonal flooding, and are particularly vulnerable during large flood events as evidenced during the 2019 spring freshet/rainfall event.

The maps available on this site identify roads that are expected to flood a minimum of 30 cm during a 1:100 flood event, as well as road segments affected by that flooding, i.e. you might not be able to safely access and evacuate your property due to road flooding elsewhere.

If your road is identified as potentially flooding during a 1:100 year event, you should plan to evacuate in advance of a major flood event, and have emergency fuel, water, and food supplies that will last a minimum of 72 hours.  You can request notification regarding water conditions by emailing info@mvc.on.ca.