Report a Suspected Blue-Green Algae Bloom

There are two ways to report:

1. Online through Ontario's Pollution/Environmental Incident Report Form

2. By phone. Call the Ministry of the Environment, Conservation and Parks (MECP) Spills Action Centre 24 hours a day, 7 days a week:

Toll-free: 1-866-MOE-TIPS (663-8477)

Toll-free TTY: 1-855-889-5775

The MECP will collaborate with us and investigate reports to determine the presence of blue-green algae and levels of blue‑green algae toxins.

What is Blue-Green Algae?

Blue-green algae are naturally occurring, microscopic, plant-like organisms that thrive in warm, calm, nutrient‑rich waters (high in nitrogen and phosphorus).

Some varieties of blue-green algae can produce cyanotoxins, which are harmful to humans and animals. 

Populations of blue-green algae can rapidly increase to form a large mass or scum, called a bloom.

Blooms are most common in late summer or early fall, and can also occur in other seasons.

Climate change is creating warmer air and water temperatures, more precipitation events and droughts, which can all strengthen the growth and toxicity of algal blooms.

Key Characteristics of Blue-Green Algae

• Appearance: Blooms often resemble spilled green paint, turquoise paint, pea soup, or globs of scum on the water surface. When a bloom very dense, it may form solid-looking mats.
• Color: While typically blue-green, they can also appear brown, red, purple or yellow.
• Location: Common in warm, slow-moving or shallow water.
• Smell: Decomposing blooms can produce a musty, grassy, or fishy smell.
• Distinction from Algae: Unlike harmless algae, cyanobacteria can produce cyanotoxins that are dangerous to human and animal health. (Blue-green algae | ontario.ca)

Safety Measures

Residents living near a lake with a blue-green algae bloom may be affected depending on how close they are to the bloom, the size of the lake, wind direction, water movement, and other environmental factors that cannot be predicted or controlled. Because of these variables, government authorities cannot determine exactly where or when toxins may be present. Individuals are advised to use caution and their own judgment.

If you live near where a blue-green algae bloom was detected, or are visiting a lake and notice algae:

• Do not use the water from the waterbody for drinking, cooking, bathing, and brushing teeth. Note: Using a private water treatment system or boiling the water does not destroy the toxins that can be produced by the blue-green algae.
• Do not swim or take part in water sports where harmful algae are present
• There is low risk to human health if you eat fish caught during a blue-green algae bloom. Toxins associated with blooms do not accumulate at high levels in fish fillets, however higher levels of toxins have been found in the livers of fish from waterbodies that regularly have blue-green algal blooms, even when a bloom is not present. Avoid eating any fish organs to eliminate this risk. Take care not to cut the organs of fish when filleting.
• If skin contact does occur, wash with soap and water or rinse thoroughly with clean water to remove algae.

If you use a private water system for your drinking water:

• If you get your water supply from your own surface water intake in the area of a blue-green algae bloom, you should seek an alternate source of drinking water (i.e. bottled water or another safe source).
• Home treatment systems may not remove toxins produced by blue-green algae.
• Do not boil or manually treat the water with chlorine or other disinfectants. This does not remove the toxins.
• Avoid using chemicals like herbicides, copper sulphate, or algaecides to kill the bloom, as this can release more toxins.
• If you have your own well supply with a groundwater source (not under the influence of surface water) or you receive trucked-in water, you can continue to use the water normally during a blue-green algae bloom.

Confirming Blue-Green Algae Blooms

All water bodies in our region are at risk of algae blooms. Precautions should always be taken during recreational use or when using water for drinking purposes.

After a suspected bloom is reported to the MECP, water samples are collected and submitted to their laboratory. Based on microscopic analysis of the algal material in the sample, the presence of blue‑green algae is identified at specific locations, which are shown on our map.

Once the MECP confirms that a sample can produce the toxins, we will issue a Public Service Announcement, notify municipalities, and ensure they have Water Advisory signs for boat launches and public beaches.

When is it safe to swim after a harmful blue-green algae bloom advisory has been released?

An advisory does not close the beach but rather advises swimmers that they need to take caution in the area. Avoid swimming if a bloom is present.

When will the public be made aware when an advisory is lifted?

Harmful blue-green algae can come and go throughout the season. The advisory does not close the beach but, rather informs swimmers to be aware that there could be a bloom in the area. Therefore, the advisory stays in place all summer, however, this does not mean the bloom will be there all summer. Look for signs of the bloom and if none are present, swimming may take place.

All water bodies in our region are at risk of an algal bloom. Precautions should be taken when using water bodies for recreation purposes or drinking water, regardless of whether a harmful algae bloom has been confirmed.

After blooms are reported, samples are taken and submitted to the Ministry of Environment Conservation and Parks Lab. Based on their analysis, blue green algae has been found at the locations indicated on our map: