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Don Mills Channel Flood Reduction

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The Don Mills Channel is a small man made channel that runs through the commercial / industrial area in the Woodbine Avenue and Denison Street area.

The Don Mills Channel was realigned and straightened in the 1960s in preparation for development.  Over time, several sections of the channel were enclosed to provide more parking on private sites, and the channel now consists of a combination of open channels and enclosed sections.  The majority of the open channel and enclosed sections are located on private property, with easements for the City to inspect and maintain the system.

Businesses surrounding the Don Mills Channel have flooded numerous times since the land was developed. Major roads in the study area, including Woodbine Avenue, can be impassable during severe storms.

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Study Area
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Estimated Flooding

This image shows the predicted extents of flooding from the August 19, 2005 storm event within the study area, and pictures taken during and shortly after the storm.

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Don Mills Flood Reduction Environmental Assessment

A Class Environmental Assessment (EA) study for the Don Mills Channel Flood Reduction was completed and approved in 2018. The purpose of the Class EA study was to:

  • Identify and understand the causes of flooding in the study area;
  • Develop a range of alternative solutions to reduce flooding and flood damages from the Don Mills Channel;
  • Recommend the preferred solution or suite of solutions to best reduce flooding and flood damages; and
  • Establish the funding, approvals and other activities needed to implement the recommended solutions.

The Study Objective is to provide flood protection for a Council Approved 5 year Level of Protection for the Don Mills Channel Area, as per the Council Resolution (February 2018) 

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Preferred Alternative

The following Preferred Alternative was proposed from the findings in the Class EA Study for the Don Mills Channel Flood Reduction (A map of the proposed works is shown below):

  • Design/construction of a central municipal flood storage facility upstream of Steelcase Road East with a proposed storage volume of 37,000 m3;
  • Replacement and upgrade of existing corrugated steel pipe culverts at Steelcase Road East, Woodbine Avenue, Denison Street and Steelcase Road West; and
  • Implementation of a flood proofing and education program in the Don Mills Channel area.
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Project Implementation Schedule
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Documents, News & Resources

Reports to Council

Environmental Assessment Files

 

The proposed structural measures (pond and culvert upgrades) recommended through the Don Mills Channel EA are meant to protect the area from the five-year storm. To help property owners and tenants within the area withstand larger storm events, the City of Markham is developing a Flood Proofing and Education Program.

 

Don Mills Channel Maintenance Program

An inspection and maintenance program for the open portions of the channel, as well as culvert inlets, was also initiated in 2017 to retain the conveyance capacity and reduce flooding potential. The program consists of the assessment and removal of live vegetation/trees, deadfall, garbage, and deposited sediment (as required).

City infrastructure (sanitary sewer, stormwater outfalls) potentially at risk of flooding or erosion in this area are also inspected regularly. Erosion risk for private properties bordering the channel is assessed periodically. Culverts are inspected following major rain events to make sure debris is not lodged in front of the culverts. City staff will remove and dispose of any significant accumulation of debris.

What can you do?

  • Avoid storing equipment, vehicles and other assets in the floodplain, especially during storms
  • Do not dump garbage on the channel bank or in the channel
  • Do not encroach into the channel. Any encroachment will need to be removed, and the channel be restored to its original condition.
Contact

Robert J. Muir, M.A.Sc., P.Eng. ,
Manager, Stormwater
8100 Warden Ave., Markham, Ontario L6G 1B4
905.477.7000 extension 2357 | rmuir@markham.ca