Updated December 18, 2025
Upstream of Allan’s Dam after 59.5 mm rainfall April 2-3, 2025
On October 28, Guelph City Council voted to keep Allan’s Dam in place without having all the necessary data to make a fully informed decision. This vote occurred as part of the approval of the Macdonell and Allan’s Structures Municipal Class Environmental Assessment (EA).
The dam increases flood risk for approximately 80 homes and 200 residents along Arthur Street North. As climate change makes extreme weather events more frequent and severe, this risk is only expected to grow.
Despite these concerns, Council overwhelmingly chose not to conduct an upstream hydraulic study. Such a study would have provided critical information, including:
- how the dam affects flood risk for nearby homes, and
- how removing the dam could help reduce that risk.
We understand that this type of study could be completed for significantly less than the cost estimate presented to Council at the last minute during that meeting. eMERGE has expressed concerns over the dam since December of 2024.
In response, we have formally challenged the decision by submitting a request to the Minister of the Environment, Conservation and Parks. This challenge is based on serious concerns about the conduct and validity of the Municipal Class Environmental Assessment process.
In particular our request outlines:
- this project incorrectly uses a Schedule B Class EA when it should be a Schedule C (higher standard) Class EA given the potential for large environmental impacts
- the removal of Allan’s Dam (Structure 320) from the study scope following its inclusion in the official Notice of Commencement, without notice, Council authorization, or legal
- the absence of a Dam Safety Review recommended under the Lakes and Rivers Improvement Act (LRIA);
- omissions of hydraulic modelling, flood-risk evaluation, spillway deterioration assessment, and climate-change analysis;
- reliance on an Evaluation Matrix developed using incomplete or selectively applied information; and
- procedural irregularities that undermine the transparency and defensibility of the EA process.
Our submission to the Minister invokes a formall process of review by the Ministry and we expect to hear the results in the new year.
CALL TO ACTION!!!
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Background – Originally posted October 25, 2025
60 mm rainfall April 2,3, 2025 – Upstream of Allan’s Dam
The City of Guelph is making an important decision about climate change, and they need all the facts. Allan’s Dam, built in the 1830s, doesn’t serve its original purpose anymore. It’s not producing energy (nor can it), mitigating floods, or augmenting flow.
We believe that removing the dam is crucial to reduce the impacts of flooding from extreme weather events
But the City doesn’t have the information they need to make that decision. The only way to know for sure is if the city completes a hydraulic study that will model the the impacts of removing the dam.
Read our detailed submission to the City here
Source: Google Earth
Removing the dam could significantly reduce the height of any flooding.
Currently, with the dam in place, 200 lives and 80 residential properties are at risk. These properties lie in the GRCA floodplain and are highly likely to flood during extreme weather. Removing the dam will greatly reduce these risks, lower flooding on MacDonell Street bridge, and possibly cut costs and risks when the bridge is rebuilt. This can also help re-naturalize shorelines, improve water quality, and lower water and air temperatures to combat climate change.
This decision affects human safety, property and natural heritage to combat climate change.
On October 28th, Guelph City Council is voting on the Macdonell and Allan’s Structures Environmental Assessment to keep the dam.
Demand they delay the vote until the hydraulic study, modelling removal of the dam, is done.
Your support can make a difference!
