The City of Toronto has initiated a study to identify sewer and watermain infrastructure within German Mills Creek that is at risk of erosion from high flows due to storms and snow melt.
This study looks at how the City’s 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 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:
To learn more about erosion in streams and rivers, view the Understanding Streams information slides.
The map below shows the location of the German Mills Creek area under study.
The study area is the two-kilometer length of German Mills Creek from Steeles Avenue East to where it meets the East Don River in the west.
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 germanmills@toronto.ca.
The study will not examine trail conditions or recommend improvements to trails, forestry or ravine amenities.
This study will follow the Municipal Class Environmental Assessment process for Master Plans, an approved planning process under the Ontario Environment Assessment Act. This study will carry out the following key steps:
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.
The study area includes 56 City of Toronto water, stormwater and sanitary sewer infrastructure sites. The level of risk due to erosion was assessed for 43 water and stormwater sites. Based on the risk assessment, 11 priority project sites were identified for further evaluation 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.
Low risk sites
Medium risk sites
High risk sites
Imminent risk sites
The map below shows the 11 sites with at-risk infrastructure identified as priority projects.
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 improvements
Alternative 2: Improvements through local works less than 200 metres
Alternative 3: Improvements through local works less that 200 metres and floodplain connections
Alternative 4: Improvements in a segment of the creek greater than 200 metres
Alternative solutions are evaluated per project, based on a range of criteria:
The following recommended solutions were made based on a risk assessment and evaluation of Alternative Solutions:
Future implementation of the recommended projects would require tree removal, followed by restoration and replanting with native trees and shrubs.
Project 1, 2, 3
Recommended solution: Local work less than 200 metres, with floodplain connections
The recommended solution for these projects:
Project 1 may require realignment of the pedestrian bridge located 500 metres west of Leslie Street to allow the stream to follow a natural course.
Projects 4, 5, 6, 7
Recommended solution: Local work less than 200 metres.
The recommended solution for these projects:
Projects 8, 9
Recommended solution: Local works less than 200 metres and floodplain connections
The recommended solution for these projects:
Project 10, 11
Recommended solution: Local works less than 200 metres
The recommended solution for these projects:
The public is invited to learn about the study, ask questions and provide feedback on the study recommendations.
Consultation Materials
Visit the study area with the project team to learn about the study recommendations and speak with members of the project team.
Friday August 18, 2023 (rain or shine)
Drop in any time between 9:00 a.m. and 11:00 a.m.
Site walk at 9:00 a.m.
Meet at the trail entrance south of Steeles Avenue on the west side of Leslie Street.
This is a wheelchair accessible venue. Please contact Aadila Valiallah at 416-338-2985 or germanmills@toronto.ca, 72 hours in advance if you require additional accommodation.
Paid parking is available at the Canadian Memorial Chiropractic College at 6100 Leslie Street.
Mandarin and Cantonese-speaking interpreters will be present at the event.
Complete the online survey or submit comments by phone or email before September 1, 2023. Contact us to request a printed copy of the survey or to be added to our email list.