TRACK 2, DAY 1
Are Urban Stormwater Ponds a Net Climate Positive or Negative?
Stephanie Slowinski, University of Waterloo and Brendan Hummelen, CF Crozier & Associates Inc.
Tuesday, March 31, 2026 | 2:15 p.m. to 2:45 p.m. | Hall F
ABSTRACT
Stormwater management ponds (SWPs) emit the greenhouse gases (GHGs) carbon dioxide (CO2) and methane (CH4) from their open water surfaces. Yet SWPs also consist of vegetated embankment and riparian zones where photosynthesis during the growing season removes CO2 from the atmosphere. Therefore, it is still not fully understood whether the whole engineered SWP system, including the vegetated zones, provide a net positive or a net negative climate impact.
In this presentation, we will present highlights of our research investigating whole system carbon budgets at two SWPs in the City of Kitchener. Key highlights are:
(1) The riparian and embankment vegetation are sinks of CO2;
(2) CH4 emissions from the open water, once converted to CO2 equivalents to account for the higher climate warming potential of CH4, outsize the CO2 sink function of the vegetation, meaning that the SWPs have a net climate warming effect despite the vegetation CO2 uptake;
(3) Riparian vegetation and soil erosion from the shoreline and bank areas of SWPs are import source of sediments and carbon to SWPs, contributing roughly 50% of the total carbon inputs at the two SWP study sites.
Our results highlight that the focus of solutions for managing the net climate effect of SWPs should be on reducing CH4 emissions, given its higher warming potential and dominant contribution to the net climate effect of the SWPs.
Options for solutions could include design and retrofitting, vegetation selection to optimize CO2 uptake and minimize soil erosion and litter inputs, maintenance operations to reduce erosion and vegetation litterfall carbon inputs, and geoengineering solutions such as geochemical amendments to reduce CH4 production.
ABOUT THE PRESENTERS
Stephanie Slowinski, University of Waterloo
Stephanie Slowinski is a Research Scientist with the Ecohydrology Research Group led by Dr. Philippe Van Cappellen at the University of Waterloo. She completed her MSc in Earth Sciences in 2019 at the University of Waterloo. She has been working since 2020 with the Ecohydrology Research Group on projects about the impact of stormwater management infrastructure on phosphorus export and greenhouse gas emissions.
Brendan Hummelen, CF Crozier & Associates Inc.
Bio coming soon.