Eroded channel conditions Newtonbrook Creek
Eroded channel conditions in Newtonbrook Creek

The City of Toronto has initiated a study to identify sewer and watermain infrastructure within Newtonbrook Creek and Blue Ridge Creek that is at risk of damage due to erosion impacts as result of high flows from storms and snow melt.

This study looks at how the City’s storm sewer and watermain infrastructure can be protected within the creek using recommended solutions to help reduce or prevent future impact. This will ensure the City’s infrastructure continues to operate and service residents and businesses. The solutions will be part of a Newtonbrook Geomorphic Systems Master Plan (GSMP) for the creek that is implemented over a multi-year period.

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, rainwater 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

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

The map below shows the location of Newtonbrook Creek and Blue Ridge Creek and the area under study.

Map of Newtonbrook Creek study area with Cummer Avenue and Willowdale Avenue at the north-west and the Don River and Sheppard Avenue at the south-east.
Map of Newtonbrook Creek study area.

The study area is the approximately 4 kilometers along the length of Newtonbrook Creek from Willowdale Avenue south of Cummer Avenue to its confluence with the Don River west of Leslie Avenue. The Study Area also includes the 2 kilometer length of Blue Ridge Creek from Bayview Avenue east to its confluence with the Don River.

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Study Purpose

The purpose of the study is to develop a Geomorphic Systems Master Plan (GSMP) for the Newtonbrook Creek and Blue Ridge Creek. The study will satisfy the following requirements of a Master Plan.

  • Identify locations within the study area where City infrastructure is at risk due to erosion
  • Develop, evaluate and recommend solutions that protect the City’s water and stormwater infrastructure from excessive erosion processes within the stream
  • Improve stream functions, such as increasing stream bank stability, reducing erosion, enhancing stormwater conveyance, and improving habitats

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

Study Process

The study is following the Municipal Class Environmental Assessment study process for Master Plans, which is an approved planning process under the Ontario Environmental Assessment Act and includes opportunities for public input.
This study will follow key steps in the process:

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

Once a GSMP is approved, recommended solutions will be included in the City’s Stream Restoration and Erosion Control Program which will prioritize and allocate budget for detail engineering design and construction.
Residents will be notified prior to any construction occurring.

Infrastructure Risk Assessment

The study area includes 72 City of Toronto water, stormwater and sanitary sewer infrastructure sites. The level of risk due to erosion was assessed for all sites, with 24 priority sites elected for improvement. These 24 high and very high risk sites were group into 11 projects due to their proximity for further assessment as part of the study.

The level of risk caused by erosion is based on a technical assessment characterizing risk probability (time to exposure), existing bank protection, and risk severity, should damage occur.

Very Low Risk Sites
Infrastructure and site conditions are very stable

Low Risk Sites

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

Medium Risk Sites

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

High Risk Sites

  • Infrastructure is not exposed but is expected within near future; Regular monitoring required

Very High Risk Sites

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

The Newtonbrook Creek information deck provides details on the risk assessment for each site.

Project map for Newtonbrook creek with the location of 11 proposed projects.
Project map. Slide 6 of the Newtonbrook presentation deck.

Alternative Solutions

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

Alternative 1: Do Nothing

No planned interventions in the stream, continued monitoring, the sanitary sewer crossing will continue to be at risk of failure due to channel downcutting

Alternative 2: Local Works
Channel engineering works less than 150 metres in length (minor local adjustment to the creek bed), bank erosion protection (armourstone walls), outfall restoration

Alternative 3: Sub-Reach Scale Works

Natural channel design in channel length greater than 150 metres, channel realignment at select locations, outfall restoration, bank erosion protection (armourstone walls, vegetate buttresses and plantings)

Evaluation framework

Alternative solutions are evaluated per project, based on a range of criteria:

  • Addresses erosion and risk to City’s water and sewer infrastructure
  • Improves stability of stream and valley walls, flood conveyance, groundwater quality, vegetation, aquatic and terrestrial habitats including habitat for at-risk species, and minimal tree removals
  • Evaluation total capital costs against are considered against recurring costs for maximum improvements and outcomes over a span of 30 years
  • Protects built and cultural heritage as we as landscape and archaeological resources, long term benefits for the community, minimum or short term negative impacts, and consideration for impacts on private property
  • Evaluation of regulatory agency standards, availability of staff and technical resources, and maximum improvement for ecosystem and infrastructure

Recommended Solutions

The following recommended solutions were made based on a risk assessment and evaluation of Alternative Solutions:

  • 4 projects are recommended for local works less than 150 metres.
  • 7 projects are recommended for sub-reach scale work greater than 150 metres

Projects 3, 5, 8, 9

Recommended solution: Local work less than 150 metres
The recommended solution for these projects:

  • Addresses identified erosion risks while minimizing the area of environmental disturbance.
  • Lower capital costs and more economically efficient than the sub-reach scale alternative given the isolated nature of the project site.

Projects 1, 2, 4, 6, 7, 10, 11

Recommended solution: Sub-reach greater than 150 metres
The recommended solution for these projects:

  • Addresses identified erosion risks through an extended restoration design improving the geomorphic stability of the degraded channel.
  • Achieves resource allocation and costing efficiencies by addressing multiple risks, located in close proximity to each other, through a single construction project.

Future implementation of the recommended projects requires:

  • Tree and vegetation removal – to be replaced with healthy native species, to be further analyzed during detailed design
  • Pedestrian trail realignment to allow the stream to have a natural course and avoid future erosion

A public site walk and drop-in information was hosted on Wednesday October 18, 2023. Members of the public were provided an overview of the study, had the opportunity to review recommended solutions ask questions and provide feedback.

Consultation Materials

Next Steps

The Environmental Assessment study report will be posted on the project webpage for a 30-day public comment period. Once approved, the recommended solutions will be included in the City’s Stream Restoration and Erosion Control Program and implementation will be prioritized across all GSMPs City-wide.
The public will be notified prior to any construction occurring.

To receive study updates by email, contact  and indicate that you would like to be added to the mailing list.