Yellow Creek Geomorphic Systems Master Plan

The geomorphology of a stream examines how natural and human factors have shaped its form and function over time. Erosion can affect the path a stream follows (form) and the aquatic and terrestrial habitats the stream supports (function). Erosion results in gradual changes to the form and function of the stream and stream bed. Significant changes to water levels contribute to increased erosion.

During storm events, rain water or snow melt runoff enters underground pipes via drains and catch basins on streets and in parks and is discharged from storm sewer outfalls into watercourses that flow to Lake Ontario. At times these flows can be high, resulting in erosion damage. High flows from past storms have caused substantial erosion damage to sewers and watermains located in and near the City’s ravines and watercourses.

This erosion damage can:

• Destabilize the soil near sewers and watermains
• Expose or break buried sewers and watermains
• Damage storm outfalls, erosion control structures, the bottom or banks of the watercourse and aquatic habitats

To learn more about erosion in streams and rivers, view the Understanding Streams information deck.

The map below shows the location of Yellow Creek and the area under study.

The study area is the 1.3 km aboveground length of Yellow Creek from south of Mount Pleasant Cemetery east of Yonge Street at Heath Street and north of St. Clair Avenue, to the southern part of David A. Balfour Park, south of Summerhill Avenue near Mount Pleasant Road.

While we aim to provide fully accessible content, there is no text alternative available for some of the content on this page. If you require alternate formats or need assistance understanding our maps, drawings or any other content, please contact us at 416-338-2985 or email yellowcreek@toronto.ca.

Study Purpose

The purpose of the study is to develop a Geomorphic Systems Master Plan (GSMP) for Yellow Creek that will include recommendations for stabilizing the creek and protecting water infrastructure from erosion. Through the study, the City:

• identified concerns related to erosion that may damage the City’s water and storm sewer infrastructure
• evaluated solutions that protect the City’s water and storm sewer infrastructure from excessive erosion processes within the stream
• recommended solutions to improve stream functions, such as increasing stream bank stability, reducing erosion, enhancing stormwater conveyance, and improving habitats

The study did not examine trail conditions or recommend improvements to trails, forestry or ravine amenities.

Study Process

The study was carried out following the requirements of the Municipal Class Environmental Assessment (MCEA) Master Planning process, where the level of investigation, consultation and documentation are sufficient to fulfill the requirements for Schedule B projects identified within the Master Plan.

Steps in the MCEA study process

1. Identify the problem or opportunity to be studied
2. Identify and evaluate alternative solutions
3. Consult public on evaluation results and study recommendations
4. Complete study report and make available for public review

Following a successful review period the Master Plan will be complete. Projects identified within the Master Plan may proceed to detailed design and implementation and will be included in the City’s stream restoration and erosion control program. Implementation will be prioritized across all GSMPs city-wide.

The Master Plan report is shared with the City’s Parks, Forestry and Recreation division and TRCA for coordination and collaboration to advance a long-range plan for Yellow Creek.

The Master Plan for Yellow Creek includes projects that are projected to be carried out in the medium term (5-10 years) and long term (beyond 10 years).

The decision for when long term projects are addressed will be assessed using several factors including a monitoring program of the existing erosion control structures, which, overall, are currently in a reasonable state of repair.

The City will issue future notification prior to any construction.

Infrastructure Risk Assessment

In Yellow Creek there are 10 City of Toronto water infrastructure sites at risk of erosion:

• Seven storm water sites
• Three watermain sites

The level of erosion risk has been assessed at each site:

Low-Risk Sites

• Infrastructure and site conditions are stable
• Limited monitoring is required

Moderate-Risk Sites

• Infrastructure and site conditions are relatively stable
• Limited/some monitoring may be required

High-Moderate-Risk Sites

• Infrastructure and site conditions show signs of erosion
• Regular monitoring is required

High-Risk Sites

• Infrastructure is exposed and/or at significant risk of failure
• Regular monitoring and improvements to the infrastructure are required

Map image of infrastructure sites.There are no high-risk sites for water infrastructure in Yellow Creek.

Alternative Solutions

The following alternative solutions for natural channel design were evaluated for the infrastructure sites at risk of erosion in the study area:

Alternative 1: Do nothing (no planned interventions, only ongoing monitoring)

Alternative 2: Improvements through local works less than 100 metres

Alternative 3: Improvements to a segment of the creek greater than 100 metres

Recommended Solutions

Based on a risk assessment of the water infrastructure sites, and following a detailed evaluation of the alternative solutions, the City is recommending four projects to stabilize the creek bed and banks of the creek through natural channel design. All four recommended projects would involve improvements to a segment of the creek greater than 100 metres (Alternative 3).

Of the infrastructure sites, one infrastructure site has been identified as moderate-high risk of damage from erosion. A portion of Project #1, which addresses the higher-risk Site 4, will be prioritized over other recommended projects for Yellow Creek.

For more detail on the project recommendations, go to the Public Consultation heading below to participate in the Virtual Meeting on November 27, 2023 or view the Virtual Public Meeting presentation deck.

Future implementation of the recommended projects will require tree and vegetation removal, followed by native species replanting. A restoration plan will be developed prior to construction as part of a future design phase after the study.

While we aim to provide fully accessible content, there is no text alternative available for some of the content on this page. If you require alternate formats or need assistance understanding our maps, drawings or any other content, please contact us at 416-338-2985 or yellowcreek@toronto.ca.

The Master Plan report is available for a 30-day review period from March 5 to April 4, 2025. See the Yellow Creek Notice of Completion for details.

• Yellow Creek Master Plan
• Yellow Creek Master Plan Appended Figures
• Appendix A-Archaeological Assessment Stage 1 Report (Part 1)
• Appendix A-Archaeological Assessment Stage 1 Report (Part 2)
• Appendix A-Archaeological Assessment Stage 1 Report (Part 3)
• Appendix A-Archaeological Assessment Stage 1 Report (Part 4)
• Appendix B-SAR Screening
• Appendix C-Flow Capacity and Bank Condition Assessment
• Appendix D-Historical Assessment
• Appendix E-Hydraulic Summary
• Appendix F-Detailed Geomorphic Assessment
• Appendix G-Terrestrial Ecology Assessment
• Appendix H-Hazard Assessment (Part 1)
• Appendix H-Hazard Assessment (Part 2)
• Appendix H-Hazard Assessment (Part 3)
• Appendix I-Climate Change Assessment
• Appendix J-Short Term Monitoring Memo (Part 1)
• Appendix J-Short Term Monitoring Memo (Part 2)
• Appendix J-Short Term Monitoring Memo (Part 3)
• Appendix J-Water Level and Discharge Monitoring Memo
• Appendix J-YCGSMP Water Quality Sampling Memo
• Appendix K-Conceptual Design Alternatives A1
• Appendix K-Conceptual Design Alternatives A2
• Appendix K-Conceptual Design Alternatives A3
• Appendix K-Conceptual Design Alternatives A4
• Appendix K-Conceptual Design Alternatives A5
• Appendix K-Conceptual Design Alternatives A6
• Appendix K-Conceptual Design Alternatives A7
•  Appendix K-Conceptual Design Alternatives A8
• Appendix K-Conceptual Design Alternatives A9
• Appendix L-Criterion Rankings Based on Effects of the Alternative Solutions
• Appendix M-Public Consultation (Part 1)
• Appendix M-Public Consultation (Part 2)

While we aim to provide fully accessible content, there is no text alternative available for the report appendices. If you require alternate formats or need assistance understanding maps, drawings or any other content, please contact us at 416-338-2985 or yellowcreek@toronto.ca.

A virtual public meeting was held on November 27, 2023. Members of the public were provided with an overview of the study, had the opportunity to review recommended solutions, ask questions and provide feedback.

Consultation Materials

• Public Meeting Summary
• Yellow Creek Virtual Public Meeting presentation
• Yellow Creek Consultation Report

Next Steps

The Master Plan report has been posted for a 30-day public review period, following which, the recommended solutions will be included in the City’s stream restoration and erosion control program. Implementation will be prioritized across all GSMPs City-wide.

The public will be notified prior to any construction occurring.