Blooms of cyanobacteria, commonly referred to as blue-green algae, are forming on lakes across British Columbia (BC) and may pose health risks to people and animals. As temperatures rise during the summer months, when blooms become more common, people using lakes are advised to look for signs of blooms and be aware of the potential risks.
Blooms caused by cyanobacteria can produce toxins that are poisonous to people, livestock, pets, and wildlife. BC Centre for Disease Control (BCCDC), Northern Health and the BC Ministry of Environment and Parks, through the BC Algae Watch website, have received reports of blooms and are reminding the public to take precautions.
Exposure to cyanobacteria toxins can cause a range of health effects from mild symptoms, such as diarrhea, dizziness and skin irritation to more severe illness affecting the nervous and respiratory systems. In rare cases, exposures can result in paralysis and death. To prevent exposure, do not drink or bathe in contaminated water and avoid recreational activities such as swimming, wading, boating, paddleboarding, and tubing in lakes with blooms. If fishing in a lake that may have a bloom, be sure to clean the fish and avoid eating the organs of the fish where the toxins may accumulate.
Toxins can be rapidly fatal to pets, livestock, and other animals if they are exposed to contaminated water by drinking, wading, playing in, or by licking their fur before being rinsed. Never let pets or livestock drink or go into the water if blooms are visible.
There is limited monitoring for cyanobacteria toxins and blooms across BC’s tens of thousands of lakes and other bodies of water. Blooms can form in any freshwater but typically occur in warm, slow-moving or stagnant water bodies. Anyone living near, recreating or using lakes should be aware of the signs of cyanobacteria blooms. Before entering a lake, check for:
- Discoloured water (blue, green, brown, yellow, orange, red, white, or purple)
- Paint-like spills or brightly coloured streaks in the water or scum or oil like sheen
- Floating mats, fluffy green mats, round globs, or looks like grass clippings
- Dead animals or accumulation of algae along the shoreline
- Blooms may smell musty or like sewage or gas
Toxins may persist after a bloom has dissipated and blooms may occur beneath the surface where they are not readily visible. Check local signage and follow advice from your local government, health authority and ministries on what water is safe to drink and where it is safe to swim.
- Do not consume untreated water from the lake and be aware that boiling does not remove toxins
- Avoid swimming and recreational activities like paddleboarding, waterskiing, canoeing, kayaking or boating which can splash water on your skin
- If contact occurs, rinse thoroughly with clean water
- Prevent pets and livestock from drinking affected water. Rinse off pets or livestock that have contacted lake water or clumps of algae along the shoreline. Do not let your pets eat dead animals, algae mats, or other debris in the water or along the shoreline.
Symptoms vary depending on the type (ingestion or skin contact) and amount of exposure.
Symptoms from consuming cyanobacteria toxins through drinking water may include:
- Dizziness
- Headache
- Nausea
- Fever
- Sore throat
- Stomach cramps/ abdominal pain
- Diarrhea
- Vomiting
- If more severe, they can include paralysis, numbness, salivation, drowsiness, speech disturbances, muscle aches, mouth ulcers and blistering of the lips.
Symptoms from skin or eye contact include:
- Rash
- Itching or blisters
- Conjunctivitis (pink eye).
If you’re showing symptoms and believe they may be from exposure to cyanobacteria, contact a health care provider.
If your pet or livestock is exposed to a bloom and experiences symptoms such as vomiting, diarrhea, tremors, stumbling, paralysis, seizures, hives, or difficulty breathing, immediately call your veterinarian or go to an emergency veterinary clinic.
The BC Centre for Disease Control, a part of the Provincial Health Services Authority, provides public health leadership through surveillance, detection, treatment, prevention and consultation services. The Centre provides diagnostic and treatment services for people with diseases of public health importance, and analytical and policy support to all levels of government and health authorities. The BCCDC also provides health promotion and prevention services to reduce the burden of chronic disease, preventable injury and environmental health risks. For more, visit bccdc.ca or follow us on Facebook or Instagram.
The Provincial Health Services Authority (PHSA) provides specialized health care services and programs to communities across British Columbia, the territories of many distinct First Nations. We are grateful to all the First Nations who have cared for and nurtured this land for all time, including the xʷməθkwəy̓əm (Musqueam), Sḵwx̱wú7mesh Úxwumixw (Squamish), and səlil̓w̓ətaɬ (Tsleil-Waututh) First Nations on whose unceded and ancestral territory our head office is located. We work in partnership with other B.C. health authorities and the provincial government to deliver province-wide solutions that improve the health of British Columbians. For more information, visit www.phsa.ca or follow us @phsa.bc. Heather Amos
BC Centre for Disease Control | Provincial Health Services Authority
778-984-1301
PHSA Media line: 778-867-7472
