System-wide SWM: Improved stormwater management at lower capital and operating costs

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March 4, 2021 @ 12:00 pm – 1:00 pm America/Toronto Timezone
Christy Graham

STEP Webinar Series 2021

Registration for this webinar has closed. If you would still like to attend please contact Amanda Slaght at


The presentation will explore a new system-wide approach to Stormwater Management (SWM). Given the major challenges associated with the current state of SWM, including limited financing, aging infrastructure, expanding urbanization, a legacy of poor planning, and older areas lacking sufficient stormwater infrastructure, the LSRCA undertook a study to evaluate an alternate approach to planning and managing stormwater. The study leveraged a pilot watershed in East Holland River in the Lake Simcoe Basin to test the hypothesis that improved environmental outcomes can be realized at lower capital and operating costs via a catchment-scale approach that includes siting centralized and distributed Stormwater Control Measures (SCMs) on both publicly-owned and privately-owned properties. State of the art process-based, open source continuous simulation models were used to evaluate millions of implementation strategies – LSPC was used for the ‘Current State’ baseline analysis and SUSTAIN was used for ‘Future State’ optimization of structural devices under growth and development, and climate change scenarios. Model outputs showed that implementing distributed and centralized on both public and private land at a catchment-wide scale, unconstrained by the limitations of municipal boundaries, provided better SWM capability at greater cost efficiency than the current and prevailing approach to SWM. The study determined that the target 40% phosphorus reduction cannot be achieved, at any cost, using the current practice of siting SCMs on public lands alone. Furthermore, planning and managing stormwater, via intermunicipal collaboration, generated a 28% cost savings and 30% reduction in SCM capacity over the current municipal, boundary-based approach to SWM. Phosphorus reduction strategies also had a significant co-benefit for peak flow control, leading to a 17-24% reduction of a 25-year return event.

Additional Information

STEP is committed to creating an accessible experience for all participants. This webinar will be hosted over Microsoft Teams, which allows participants to enable live captions during the event. If you require assistance with this feature or a different accommodation, please email at least 7 days prior to the event.

Please note that audio and video will be recorded during this webinar. If you do not consent to being recorded, please contact us at to discuss your concerns, or do not join the session.

Space is limited. Registration has closed. 

This webinar is part of the STEP Water 2021 Webinar Series.