Highland Creek Markham Branch (Corporate Dr.) Flood Remediation Municipal Class Environmental Assessment

Public Consultation #1

The first public consultation for the Highland Creek Markham Branch (Corporate Dr.) Flood Remediation Project was held virtually from November 30 to December 16, 2022

The online public consultation information showcased the project overview, the alternative solutions evaluated and evaluation results, the preferred alternative solution, and next steps on the project.

The comment period is now closed. However, the public consultation information is still available to view at the link below.


Toronto and Region Conservation Authority (TRCA) together with the City of Toronto have initiated a Municipal Class Environmental Assessment (EA) to determine a preferred flood remediation solution in order to help mitigate the risk of riverine flooding within part of the Progress Business Park Flood Vulnerable Area (FVA).

The flood remediation strategy will minimize the risk of riverine flooding on roads, and on residential and commercial lands, thereby protecting existing residents and businesses from flooding.

Explore the Project

*Image courtesy of City of Toronto.


The primary objective of the Highland Creek Markham Branch (Corporate Dr.) Flood Remediation EA is to find a preferred solution for minimizing riverine flooding within the study area.

The study will aim to minimize the risk of riverine flooding to roads, and to residential and commercial land, protecting existing residents and businesses, and will also unlock the potential for redevelopment opportunities within the southern portion of the Progress Business Park FVA.

This study will incorporate and expand on the Technical Feasibility Study completed by the City of Toronto and TRCA in 2020.

TRCA, in conjunction with the City of Toronto, will undertake the EA process in accordance with the requirements for Schedule C projects. Upon completion of the study, an Environmental Study Report (ESR) documenting the planning and decision-making processes will be prepared for public and agency review and comment.

There will be public and stakeholder consultation opportunities over the course of the study, per the EA process. Public notice of future consultation events will be advertised in the Scarborough Mirror newspaper in advance, posted on this website, and emailed directly to the project mailing list.

If you would like to be added to the project mailing list, please contact us.

Project Goals:

The Highland Creek Markham Branch (Corporate Dr.) Flood Remediation EA will seek to:

  • Define a preferred riverine flood mitigation strategy for the downstream portion of the Progress Business Park FVA
  • Complete the associated environmental assessment
  • Identify methods for the delivery of the mitigation strategy, such as including a phasing plan for implementation

The design of the riverine flood mitigation strategy will seek to:

  • Minimize riverine flood risk in the study area with robust and low maintenance cost-effective solutions
  • Minimize and mitigate impacts resulting from the implementation of flood remediation
  • Coordinate riverine flood mitigation designs with other City projects in the study area.


Select image below to view the full-sized map.

Highland Creek Markham Branch Environmental Assessment Study Area Map
Scoped Study Area (red line) captures where all flood remediation infrastructure alternatives are located, along with direct impacts and benefits as a result of the project, such as construction impacts. Broad Study Area (green dotted line) looks at the external benefits north of Highway 401 due to any infrastructure improvements that are proposed south of Highway 401 within the Scoped Study Area.


The project study area identified for this project is the Markham Branch of Highland Creek within the Progress Business Park FVA.

The Markham Branch of Highland Creek is surrounded by high-density residential and commercial lands as it flows southeast from Highway 401 to the Bellamy Road North crossing, and then east to Markham Road.

During infrequent storm events water spills out of the river and floods adjacent roads and lands within the study area. This flood plain not only puts people and property at risk during storm events, but also restricts opportunities for growth and redevelopment in this area.

The channel within the study area was realigned and engineered over 50 years ago. Reconstruction of the channel was initiated in the late 1990s and was completed in 2002, using natural channel design principles.

Highland Creek Markham Branch
View of the Highland Creek (Markham Branch) bounded on the west by McCowan Road, Highway 401 to the north, Markham road to the east and Ellesmere Road to the south. Image courtesy of City of Toronto.

Recent observations have identified that the channel has started to degrade due to erosion of bed material and bed structure. The Highland Creek watershed overall has poor surface water quality.

In 2019, TRCA completed a Flood Risk Assessment and Ranking Project to identify the areas of the greatest flood risk within TRCA’s jurisdiction, called Flood Vulnerable Areas (FVAs).

FVAs were ranked based on severity of impacts under multiple criteria including infrastructure, economics, community and social vulnerabilities as well as flood preparedness/resiliency.

The Progress Business Park FVA is located within the City of Toronto along the Markham Branch of Highland Creek and includes the area from Bellamy Road North extending north of Highway 401.

This FVA is the third highest-ranked FVA within the City of Toronto for potential impacts due to riverine flooding, and is among the top 10 highest-ranked FVAs within TRCA’s jurisdiction.

It was understood that the flooding is largely the result of undersized culverts restricting flow, causing water to back up upstream of the culverts.

In 2010, Toronto City Council approved the redevelopment of the lands at the southeast corner of Corporate Drive and Consilium Place subject to a Holding (H) provision until an acceptable flood plain and stormwater management plan is developed and substantially implemented.

The decision directed staff to undertake a Flood Remediation Study to investigate the feasibility, cost, and options to remove the flooding risk.

A Technical Feasibility Study (Stage 1) was initiated to better understand the existing conditions of the channel and related infrastructure to help determine feasible solutions for flood mitigation, and was completed in 2020.

This EA study (Stage 2) will build upon the feasibility study to evaluate and identify a preferred solution for implementation, following the EA process.


The Highland Creek Markham Branch (Corporate Dr.) Flood Remediation EA is following the Class Environmental Assessment process for municipal infrastructure projects outlined by the Municipal Engineers Association and approved by the Minister of the Environment and Climate Change.

The study is being undertaken in two stages:

  • Stage 1: Technical Feasibility Study (Completed)
    • Problem, opportunity, and constraints identified through assessments of existing channel conditions and related infrastructure
    • Screening of flood mitigation options and subsequent high-level design of the feasible options which provide adequate flood protection

Relevant information from the Technical Feasibility Study will be incorporated into the EA.

  • Stage 2: Municipal Class Environmental Assessment (Ongoing)
    • Development of alternative solutions based on findings from the Technical Feasibility Study, including additional consideration of upstream flood risk benefits
    • Public and stakeholders consultation on the alternative solutions
    • Selection of the preferred solution using a multi-faceted assessment considering technical, cost, environmental, cultural and social factors

Refer to the Stage 2 timeline below

Stage 2 Timeline

public consultation icon – Marks points of public consultation.
public consultation Summer 2022
Notice of Project Commencement
lightbulb icon Summer 2022
Baseline Inventory, Problem & Opportunity
alternative solutions icon Fall 2022
Develop and Assess Alternative Solutions
public consultation Winter 2022
Public Consultation #1
design concepts icon 2023
Develop and Assess Design Concepts for Preferred Solution
In progress
public consultation Winter 2024
Public Consultation #2
Not Yet Commenced
environmental study report icon Spring & Summer 2024
Prepare Environmental Study Report
Not Yet Commenced
public consultation Summer 2024
Public Review of Environmental Study Report
Not Yet Commenced
environmental assessment approval icon Summer 2024
Anticipated Completion of EA
Not Yet Commenced


Notice of Commencement and Public Consultation Event #1: September 2022

Public Consultation #1: Comment Period November 30–December 16, 2022

Public Consultation #2: Spring 2023


Have questions? Want to join the project mailing list? Please contact:

Highland Creek Markham Branch (Corporate Dr.) Flood Remediation EA Project Team
Toronto and Region Conservation Authority (TRCA)
101 Exchange Avenue, Vaughan ON L4K 5R6
Email: HCMBfloodEA@trca.ca
Phone: (647) 426-4520