Residents may notice some of Brampton’s stormwater ponds turning green or cloudy over the coming weeks, but the City says seasonal algae growth is generally a normal part of the pond ecosystem and usually not a cause for concern.
The City of Brampton says algae growth is most noticeable from mid-July through mid-September, when warmer temperatures and other seasonal conditions can encourage algae to develop in stormwater ponds.
Brampton has more than 180 stormwater ponds that play an important role in managing runoff, reducing the risk of flooding, improving water quality and supporting local ecosystems.
Stormwater ponds are designed to temporarily hold rainwater and melted snow flowing from surrounding neighbourhoods. As runoff travels across rooftops, roads, sidewalks and parking lots, it can collect sediment, nutrients and other pollutants.
Once the water reaches a stormwater pond, sediment and pollutants are given time to settle before cleaner water is gradually released into local creeks and rivers.
Because these ponds collect runoff from across the community, their appearance can change considerably throughout the year. Water levels, aquatic vegetation and algae growth can vary depending on rainfall, temperature and other seasonal conditions.
The City says some algae in ponds, lakes and rivers is natural and plays an important role in aquatic ecosystems. However, residents should be aware of the possibility of blue-green algae, also known as cyanobacteria.
Under certain conditions, particularly warm temperatures combined with elevated nutrient levels, blue-green algae can multiply rapidly and create blooms.
Most algae are not harmful, and not every blue-green algae bloom produces toxins. However, some blooms can, in rare circumstances, produce toxins that may pose health risks to people, pets and wildlife.
Potential blue-green algae blooms can have several noticeable characteristics. The surface of the water may develop a blue-green or turquoise film, appear as though paint has been spilled across it, become thick and green like pea soup or contain clumps resembling fine grass clippings.
Laboratory testing is required to determine whether a suspected bloom is actually blue-green algae.
Residents who believe they have encountered a possible bloom are advised not to enter the water and to keep children and pets away from the pond and shoreline.
Suspected blue-green algae blooms can be reported to the Ontario Spills Action Centre at 1-866-663-8477 or Peel Public Health at 905-799-7700. Residents who are unsure where to report a concern or have general questions about Brampton’s stormwater ponds can contact 311.
If testing confirms a bloom, advisory signs are installed around the affected pond to alert residents and help prevent contact with the water.
The City is also asking residents to help reduce the amount of nutrients and pollutants entering Brampton’s stormwater system.
Using fertilizers sparingly, cleaning up pet waste and preventing leaves and grass clippings from entering streets and storm drains can help improve water quality. Residents are also reminded never to dump chemicals, waste or other materials into catch basins.
Reducing pollutants and excess nutrients entering the stormwater system can limit conditions that contribute to excessive algae growth while helping protect Brampton’s creeks, rivers and other waterways.
With seasonal algae growth expected during the warmer months, the City’s main message is that green water does not automatically mean a pond is dangerous. However, residents should avoid contact with suspicious blooms and report anything that appears to resemble blue-green algae.