Close Alert Banner

Living Here Background image

Skip to Content

City of Kenora Logo

Contact Us
Contact Us
  • Living Here
    • Accessibility and Inclusion
    • Animal Services
    • Building and Renovating
    • Cemetery
    • Childcare
    • Education
    • Emergency Services and Preparedness
    • Environment
    • Healthcare
    • Libraries
    • Parking
    • Property Taxes
    • Recycling and Garbage
    • Roads and Traffic
    • Seniors Services
    • Social Services
    • Transit
    • Utilities
    • Water and Sewer
  • Visit & Play
    • Recreation Centre
    • Admission and Membership
    • Advertising and Sponsorships
    • Amenities
    • Aquatics and Swimming
    • Arenas and Skating
    • Camps
    • Community Organizations
    • Facilities and Rentals
    • Fitness
    • Parking at Arenas
    • Visit Kenora
    • Beaches, Trails and Parks
    • Boating
    • Community Calendar
    • Outdoor Adventure
    • Plan your Trip
    • See and Do
    • Arts and Culture
    • Art Centre
    • Art Organizations
    • Heritage and History
    • Libraries
    • Powwows
    • Museums
    • Volunteer
  • Build & Invest
    • Building and Renovating
    • Business Licences and Permits
    • Community Improvement Plans
    • Current and Active Projects
    • Economic Development
    • Economic Profile and Data
    • Maps
    • Physician and Healthcare Professional Recruiting
    • Planning and Development
    • Start or Expand Your Business
    • Tenders and Request For Proposals
  • Your Government
    • A-Z Services
    • Accessibility and Inclusion
    • Agenda and Minutes
    • Applications, Licences and Permits
    • Budget and Finances
    • By-laws and Enforcement
    • Citizen Recognition Award
    • Committees and Boards
    • Elections
    • Freedom of Information
    • Jobs
    • Mayor and Council
    • Plans Studies and Reports
    • News and Notices
    • Policies
    • Provincial Offences
    • Tenders and Request For Proposals
  • I Want To
    • Apply and Register
    • Building Permits
    • Business Licences and Permits
    • Burning Permits
    • Dog Licences
    • Marriage Licences and Ceremonies
    • Road Permits
    • Pay
    • Bag Tags
    • Fines and Traffic Tickets
    • Ice Candles
    • Parking
    • Property Taxes
    • Water Bill
    • Get Involved
    • Mayor and Council
    • Environment
    • Presenting to Council
    • Run for Council
    • Volunteer
    • Work for the City of Kenora
City of Kenora Logo

Blue-green Algae

HomeLiving HereEnvironmentBlue-green Algae
  • Open new window to share this page via Facebook Facebook
  • Open new window to share this page via Twitter Twitter
  • Open new window to share this page via LinkedIn LinkedIn
  • Email this page Email

When the conditions are right, toxic blue-green algae can be present in water bodies surrounding the City of Kenora. Unless you receive a notice from the City of Kenora or the Northwestern Health Unit, the presence of blue-green algae does not affect the municipal drinking water supply.

What blue-green algae looks like

Algal blooms are solid-looking clumps that look blueish-green, or like green pea soup or turquoise paint.

Blue green algae on a lake during a bloom

Colonies of microscopic blue-green algae appear on a lake during a bloom. Blooms occur mostly during late summer and early fall.

Be cautious

  1. If you suspect a blue-green algal bloom, assume toxins are present, and call the Spills Action Centre at 1-800-268-6060.
  2. Avoid using the water
  3. Restrict pet and livestock access to the water
  4. Avoid activities that increase exposure to toxins during algal blooms;
  5. Contact the Northwestern Health Unit for information and follow their advice.

Prevent growth of blue-green algae

  • use phosphate-free detergents, personal care and household cleaning products
  • avoid using fertilizers on lawns, especially fertilizers that contain phosphorus
  • maintain a natural shoreline on lake and riverfront properties
  • reduce agricultural runoff by planting or maintaining vegetation along waterways and minimize fertilizer use, and
  • check septic systems to ensure they do not leak into the water source

What are blue-green algae?

Cyanobacteria, commonly called blue-green algae, are primitive microscopic organisms that have inhabited the earth for over 2 billion years. They are bacteria, but have features in common with algae. Although often blue-green (their scientific name cyanobacteria comes from the Greek word for blue), they can range in colour from olive-green to red. Blue-green algae occur naturally in a wide variety of environments including ponds, rivers, lakes and streams.

What are blue-green algae blooms?

Normally blue-green algae are not visible in the water, but when conditions are favourable, algal populations can rapidly increase to form a large mass or scum in the water called a bloom. Blooms most commonly occur during the warmer weather of late summer and early fall.

What conditions favour algal growth?

Blue-green algae thrive in areas where the water is shallow, slow moving and warm, but they may also be present in deeper, cooler water. One key factor affecting the growth of blue-green algae is the amount of available nutrients such as phosphorus and nitrogen. In Ontario water bodies, phosphorus tends to be the nutrient that controls how much algae can grow.

How can blue-green algal blooms be reduced or prevented?

Human activities can promote the growth of blue-green algae. For instance, agricultural, urban and stormwater runoff, effluent from sewage treatment plants and industry, and leaching from septic systems can elevate the levels of nutrients in water bodies, which can promote algae growth. Reducing or eliminating nutrient inputs from these sources is a proactive way to reduce the occurrence of blue‑green algal blooms.

Take these simple steps to prevent the growth of blue-green algae:

  • use phosphate-free detergents, personal care and household cleaning products
  • avoid using fertilizers on lawns, especially fertilizers that contain phosphorus
  • maintain a natural shoreline on lake and riverfront properties
  • reduce agricultural runoff by planting or maintaining vegetation along waterways and minimize fertilizer use, and
  • check septic systems to ensure they do not leak into the water source

How do I recognize a blue-green algal bloom?

Dense blue-green algal blooms may make the water look like bluish-green or green pea soup or turquoise paint. Colonies of microscopic blue-green algae appear on a lake during a bloom. Blooms occur mostly during late summer and early fall. They may form solid-looking clumps. Fresh blooms often smell like newly mown grass; older blooms may smell like rotting garbage.

What should I do if I encounter a bloom?

Take a cautious approach with blue-green algal blooms. Although many varieties of blue-green algae are harmless, some can produce toxins that are harmful to the health of both humans and animals. These toxins are contained within the algal cell and are released to the water when the cell wall breaks, which can occur when the cell dies and decomposes or is damaged by abrasion, or by chemicals like bleach or algaecides. Higher levels of toxins may occur when blue-green algal cell numbers are high and concentrated in one area. As a precaution, regard any blue-green algal bloom as potentially toxic.

Is it safe to swim in a water body where blue-green algal blooms occur?

During an algal bloom, avoid activities such as swimming and bathing in water near the bloom to reduce the risk of exposure to algal toxins. Contact your local Health Unit swimming advisories as well as information on health risks associated with blue-green algal blooms.

If I see a bloom and suspect it is blue-green algae, what immediate actions should I take?

If you suspect a blue-green algal bloom:

  • assume toxins are present
  • avoid using the water
  • restrict pet and livestock access to the water, and
  • call the Ministry of Environment, Conservation and Parks Spills Action Centre at 1-800-268-6060.

Can blue-green algal blooms be treated in the water body?

Treating blooms with herbicides, copper sulphate or other algaecides is not advised because these treatments may break open algal cells and release more toxins into the water. This characteristic makes treating algal blooms difficult. Prevention is the best way to control algal blooms.

What are the potential health effects associated with blue-green algal toxins?

The severity of symptoms and the level of risk to health depend on how you are exposed to blue-green algal toxins. Human health effects from contact with these toxins may include:

  • itchy, irritated eyes and skin from direct contact through activities such as swimming and water skiing, and
  • if large quantities of the toxins are swallowed, flu-like symptoms, such as headache, fever, diarrhea, abdominal pain, nausea and vomiting.

How much microcystin is allowable in drinking water under the Ontario drinking water quality standards?

The Ontario Drinking Water Quality Standard for microcystin-LR (a common algal toxin) is a maximum acceptable concentration of 1.5 micrograms per litre, which is the same as 1.5 parts per billion. It is rare for treated water tests in Ontario to exceed this standard, but precautions should still be taken when a bloom occurs.

Can I use my water if I know there is a bloom nearby?

If you are connected to a municipal water supply system or other central water treatment and distribution system, you can continue to use the water normally unless notified otherwise by the system operator or the local health unit. Central treatment plants usually have filtration, chlorination, and other treatment systems that are capable of removing the algal cells and toxins.

Drinking Water System Operators will monitor drinking water quality more frequently once a bloom is reported in the area of the intake. If you have your own well supply with a groundwater source (not including shore wells or infiltration galleries), or you receive trucked water in cisterns, you can also continue to use the water normally.

If you get your water supply from your own surface water intake in the area of a bloom, you should consider an alternate source of drinking water for the duration of the bloom. Usually people won't drink water contaminated with blue-green algal blooms because of its unsightly pea soup appearance and foul smell.

If you have your own surface water supply and are unsure about the safety of your drinking water during an algal bloom, use alternative water sources such as bottled, carted or tanked water. You can also call a water treatment service provider for help.

However, sometimes specialized tests for algal toxins are needed to tell if your drinking water has been contaminated. Home treatment systems may not remove toxins and can get easily overwhelmed or clogged, so they should not be relied on. Do not boil the water, or manually treat the water with chlorine or other disinfectants, as this could increase the toxin levels. Contact your local Health Unit for more information.

Alga bloom

During an algal bloom such as this, avoid swimming and bathing in water near the bloom, to reduce the risk of exposure to algal toxins. Contact your local Health Unit for any health-related information.

Living Here
  • Environment
    Toggle Section Environment Menu
    • Adopt a Block and Clean Leaf Programs
    • Blue-green Algae
    • International Watershed
    • Plans Studies and Reports
    • Releasing Helium Balloons
  • View Full Living Here Menu
    Toggle Section
    • Accessibility and Inclusion
      Toggle Section Accessibility and Inclusion Menu
      • Accessible Parking
      • Handi Transit
    • Animal Services
      Toggle Section Animal Services Menu
      • Deer Management
      • Dog Licences
      • Stray Pets
      • Wildlife
    • Building and Renovating
    • Cemetery
      Toggle Section Cemetery Menu
      • Ice Candles
      • Walking Tours
    • Childcare
    • Education
    • Emergency Services and Preparedness
      Toggle Section Emergency Services and Preparedness Menu
      • Ambulance
      • Fire Services
        Toggle Section Fire Services Menu
        • About Us
        • Burning Permits
        • Fire Inspections
        • Fire Prevention and Public Safety
        • Fire Stations and Vehicles
        • Paid On Call Firefighter Recruitment
      • First Aid Training
      • Lake of the Woods Search and Rescue
      • Womens Shelter
    • Healthcare
    • Libraries
    • Parking
      Toggle Section Parking Menu
      • Accessible Parking
      • Provincial Offences
      • Veterans Plate Parking
    • Property Taxes
      Toggle Section Property Taxes Menu
      • Paying Property Taxes
      • Tax Certificates
      • Tax Sales
      • Unincorporated Properties
    • Recycling and Garbage
      Toggle Section Recycling and Garbage Menu
      • Bag Tags
      • Christmas Tree Recycling
      • Coney Island Lake Collection
      • Household Hazardous Waste
      • Leaf and Yard Waste Composting
      • Recycling
      • Waste Transfer Facility
    • Roads and Traffic
      Toggle Section Roads and Traffic Menu
      • Adopt a Block and Clean Leaf Programs
      • Parking
      • Road Maintenance
      • Road Permits
      • Roundabout
      • Snow Removal
      • Weight and Load Limits
    • Seniors Services
    • Social Services
    • Transit
      Toggle Section Transit Menu
      • Bus Routes
      • Handi Transit
    • Utilities
    • Water and Sewer
      Toggle Section Water and Sewer Menu
      • Paying Your Water Bill
      • Reading Your Water Meter
      • Service Connections
      • Treatment Facilities
      • Water Account Setup
      • Water Delivery
      • Water Stations
      • Watermain Breaks

Contact Us

Subscribe to Page Updates

City of Kenora footer logo

Your Government
1 Main Street South
Kenora ON P9N3X2
Phone: 807-467-2000
After hours: 807-467-2080

  • A-Z Services
  • Accessibility and Inclusion
  • Freedom of Information
  • Sitemap
  • Website Feedback
  • Contact Us
  • Facebook
  • Twitter
  • Instagram
  • Podcast

© 2020 The Corporation of the City of Kenora

Designed by eSolutionsGroup
Close Old Browser Notification
Browser Compatibility Notification
It appears you are trying to access this site using an outdated browser. As a result, parts of the site may not function properly for you. We recommend updating your browser to its most recent version at your earliest convenience.