BRAMPTON, ON – From mid-July to mid-September, Brampton’s stormwater ponds may take on a green or cloudy appearance as warmer temperatures contribute to increased algae growth. While the change may be noticeable, most algae growth is a normal part of the pond ecosystem and is not a cause for concern. With more than 180 stormwater ponds across Brampton helping to manage stormwater runoff, reduce flood risk, improve water quality and support local ecosystems, the City is sharing what residents should know about seasonal algae.​

What are stormwater ponds? 

Stormwater ponds are designed to temporarily store stormwater, giving sediment and pollutants time to settle before cleaner water is gradually released into local creeks and rivers.

These ponds collect rainwater and snowmelt runoff from surrounding neighbourhoods. As water flows over rooftops, roads, sidewalks and parking lots, it carries sediment, nutrients and other pollutants into the pond.​

Why do stormwater ponds turn green?

Because stormwater ponds collect runoff from across the community, their appearance naturally changes throughout the year. Water levels, aquatic plants and algae can all vary depending on rainfall, temperature and seasonal conditions. In most cases, some algae growth is a normal part of a healthy, functioning stormwater pond.

Blue-green algae (cyanobacteria) are one type of naturally occurring algae. Under certain conditions, including warm temperatures and elevated nutrient levels, they can multiply rapidly and form blooms. 

Not all algae are harmful. Algae naturally occur in ponds, lakes and rivers and play an important role in healthy aquatic ecosystems. While not every bloom produces toxins, in rare cases, some blue-green algae can produce toxins that may be harmful to people, pets and wildlife.

How to recognize a potential blue-green algae bloom

Although laboratory testing is needed to confirm a bloom, potential blue-green algae may appear as: 

• A blue-green or turquoise film on the water's surface 
• Water that looks like spilled paint
• Thick green water resembling pea soup
• Clumps that resemble fine grass clippings 

A photo of a blue green algae bloom. Credit: Credit Valley Conservation​

What to do if you suspect a bloom

If you believe you’ve identified a potential blue-green algae bloom:

• Do not enter the water
• Keep children and pets away from the shoreline 
• Report a suspected blue-green algae bloom to: 
• ​Ontario Spills Action Centre: 1-866-MOETIPS (663-8477), TTY: 1-855-889-5775 
• Peel Public Health: 905-799-7700 
  

Residents with general questions about stormwater ponds or who are unsure where to direct their concerns can also contact 311 for assistance. If a bloom is confirmed, advisory signage around the affected pond is installed to notify the public and help keep residents safe.​

Help protect Brampton's waterways

Everyone can help protect local water quality by reducing the amount of nutrients entering Brampton’s stormwater ponds.​

Residents can help by:

• Using fertilizers sparingly
• Picking up pet waste
• Keeping leaves and grass clippings out of streets and storm drains 
• Never dumping waste, chemicals or other materials into catch basins. 
  

These simple actions help reduce excess nutrients entering stormwater ponds and keep Brampton's waterways healthier for people, pets and wildlife.

To learn more about stormwater ponds, water quality, seasonal algae and frequently asked questions, visit the City's Stormwater Pond FAQ webpage​. ​