A new report brought forward at the City of Hamilton’s Public Works Committee details new measures that the municipality will take to mitigate algae blooms in areas of the West Harbour.
New mitigation approaches include aeration, mechanical circulation, riparian and aquatic plantings, floating treatment wetlands, continued goose management, and potentially mechanical removal.
The city has also identified site-specific implementation areas for the new measures, with aeration set to take place at Bayfront Park Beach, nature-based solutions planned for Macassa Bay, and aeration and circulation planned for Piers 5-7.
There will also be various control sites to compare performance.
Future pilot areas identified are Bayfront Park Boat Launch and Pier 8 to HMCS Haida, but action at both of those locations will be deferred for now.
While procurement and vendor engagement are underway, and staff hope to see some benefits by Fall 2026, they add that most of the improvements will not be seen until 2027.
Implementation timelines are impacted by specialized equipment requirements, limited vendor options, regulatory permits, and approvals.
Staff added that there are temporary measures that can be taken this year if the blooms are bad, including mechanical removal of the blooms themselves, but that practice has normally seen the algae come back within a week.
Discussion regarding new mitigation measures to address the West Harbour algae blooms peaked in 2024, when nearshore areas, including Bayfront Park and Pier 4 Park Beach, saw a significant algal bloom.
The city report says that the bloom resulted in “odours, visible algal mats, and impacts to public use and aesthetics.”
Staff say that algal blooms in 2025 were smaller due to a colder spring season.
This year is expected to be similar to 2025.
Staff explained that algal blooms in Hamilton Harbour are driven by “elevated nutrient levels, warm water temperatures, hours of direct sunlight, and localized stagnant flow in protected portions of the West Harbour.”
In 2025, the city retained Stantec Consulting Ltd. at a cost of approximately $139,000 to complete data analysis, an industry scan, and recommend mitigation options.
Stantec reviewed over 650,000 water quality and sediment data records and historical bloom observations.
Staff say the findings “confirm that the West Harbour nearshore environment is nutrient-rich and generally conducive to harmful algal blooms.”
“The release of nutrients (nitrogen, phosphorus, carbon) from the harbour sediment, combined with ongoing inputs of nutrients from goose droppings, combined sewer overflows, and other sources, contributes to recurring bloom events,” the report continues.
Mike Christie, Senior Project Manager of Watershed Management at the City of Hamilton, told the committee, “We are contemplating a fair bit of plantings, both in and around the water, to help with uptake of nutrients that cause algae blooms and to actually help deter free movement of geese, which we found is really the primary source of our issues.”
The planned mitigation measures are expected to reduce visible algal mat accumulation, reduce odour issues, and reduce bloom frequency and duration.
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