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Safe Water

Blue-green algae

If you suspect a blue-green algal bloom, call the Pollution Hotline at 1-866-663-8477.

For information on the health risks associated with blue-green algal blooms, please contact Health Connection at 705-721-7520 or toll-free at 1-877-721-7520 to speak with a public health inspector.

The Ministry of the Environment, Conservation and Parks (MECP) collects and tests algae samples and reports the results to the health unit.

2022

Affected Waterway

Municipality

Date Public Notice Issued

Status

Fairlain Lake (Southeast and Southwest Shoreline)

Township of Tiny

July 30, 2022

ACTIVE

2021

Affected Waterway

Municipality

Date Public Notice Issued

Status

Hammell’s Bay, Three Mile Lake (North Shoreline)

Township of Muskoka Lakes

August 19, 2021

RESOLVED - January 27, 2022

Three Mile Lake (South Shoreline)

Township of Muskoka Lakes

October 6, 2021

RESOLVED - January 27, 2022

Little Lake (Southeast and Southwest Shoreline)

Township of Georgian Bay

July 28, 2021

RESOLVED - November 10, 2021

Stewart Lake (Southeast Shoreline)

Township of Georgian Bay

July 30, 2021

RESOLVED - November 10, 2021

Kahshe Lake

Town of Gravenhurst

October 8, 2021

RESOLVED - November 10, 2021

Mary Lake (Port Sydney beach area)

Town of Huntsville

October 22, 2021

RESOLVED - November 10, 2021

Menominee Lake (North Menominee Lake Road Area)

Town of Huntsville

November 10, 2021

RESOLVED - December 3, 2021

Fawn Lake (North-West Corner)

Town of Huntsville

November 10, 2021

RESOLVED - December 3, 2021

Paint Lake (Northwest end)

Township of Lake of Bays

August 13, 2021

RESOLVED - November 10, 2021

Lake St. John (North and South Shorelines)

Township of Ramara

August 13, 2021

RESOLVED - December 6, 2021

Leonard Lake (South End)

Township of Muskoka Lakes

August 31, 2021

RESOLVED - October 18, 2021

Bass Lake (North shore of Bass Lake)

Township of Muskoka Lakes

November 10, 2021

RESOLVED - December 7, 2021

Blue-green algae, technically known as cyanobacteria and Harmful Algal Blooms, are microscopic organisms that are naturally present in lakes and streams. They are usually present in low numbers but can rapidly increase in warm, shallow, undisturbed surface water that gets a lot of sun. When this happens, they can form blooms that discolour the water or produce floating scum on the surface of the water.  Blooms often make the water look blue-green or olive-green, or like green pea soup or turquoise paint. 

Some blue-green algae produce toxins (Government of Canada) that can pose a health risk to people and animals when they are exposed to them in large amounts. Your health may be impacted when surface scum or water containing high levels of blue-green algal toxins are swallowed, come into contact with the skin, or when airborne drops containing toxins are inhaled while swimming, bathing or showering.

Consuming water

Ingestion of high levels of blue-green algal toxins have been associated with effects on the liver and nervous system in laboratory animals, pets, livestock and people. Livestock and pet deaths have occurred when animals consumed large amounts of algal scum.

Direct contact, or breathing airborne droplets

Coming in contact with high levels of blue-green algal toxins while swimming or showering can irritate the skin, eyes and throat and inflame the respiratory tract.

Recreational contact

Swimming and household contact, such as bathing or showering, with water not visibly affected by a blue-green algae bloom is not expected to cause health effects. However, some individuals can be especially sensitive to even low levels of algal toxins and might experience mild symptoms such as skin, eye or throat irritation or allergic reactions.

Never drink untreated surface water, whether algae blooms are present or not. Untreated surface water may contain other bacteria, parasites or viruses, as well as algal toxins that could cause illness if consumed.

People using private water supplies that are impacted or draw from a waterbody should not drink water during an algal bloom, even if it is treated. In-home treatments such as boiling and disinfecting water with chlorine or UV and water filtration units do not protect from blue-green algal toxins.

People, pets and livestock should avoid contact with water that is discoloured or has scum on the surface. If contact does occur, wash with soap and water or rinse thoroughly with clean water to remove algae.

Stop using the water and seek medical attention if symptoms such as skin, eye or throat irritation, allergic reactions or breathing difficulties occur while in contact with untreated surface water. However, swimming, bathing or showering with water not visibly affected by a blue-green algae bloom is not expected to cause health effects.

Do not eat the liver, kidneys and other organs of fish caught in the waterbody. Be cautious about eating fish caught in water where blue-green algae blooms occur.

If you suspect a blue-green algal bloom, be cautious and assume that toxins are present.  Avoid exposure to the blue-green algae.

If you spot a bloom, report it to the Pollution Hotline at 1-800-663-8477.

For information on the health risks associated with blue-green algal blooms please contact Health Connection at 705-721-7520 or toll-free at 1-800-721-7520 to speak with a public health inspector.


External Links

Adapted with permission from Public Health Sudbury & Districts
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