Blue-green algae

Blue-green algae appear in the water as greenish or yellowish sticks and bits. A large amount of blue-green algae can accumulate on the surface of the water as rafts of algae, and the mass of algae washed ashore can resemble thick paint or pea pods. Blue-green algae are characterized by a musty, earthy smell.

The toxicity of blue-green algae depends on the algae species and the conditions. Even in the same algae deposit, some of the algae mass can be toxic and some not, so blue-green algae water must always be treated as if it were toxic.

If there is or has recently been blue-green algae in the water:

• the water must not be used as drinking water for humans or animals
• do not use as dishwater
• do not use as washing water
• do not use as soaking water
• do not use for watering edible plants
• swimming in water rich in algae should be avoided. Children and pets are not allowed on the beach or to swim
• the meat of fish caught in the blue-green algae area can be eaten, but the use of internal organs should be avoided. In addition, you should wash both the fish and your hands carefully with clean water

People's sensitivity to the symptoms caused by blue-green algae varies greatly. If you suspect that you swam in blue-green water, wash yourself with clean water after swimming. Blue-green algae can cause skin redness and itching, eye or nose symptoms, as well as vomiting and diarrhea. Symptoms usually appear within a few hours of exposure to blue-green algae. If symptoms occur, wash the skin and eyes carefully with plenty of clean water. If you suspect poisoning, see a doctor or take the animal to a veterinarian.

 Blue-green algae identification.pdf

Algae observations can be easily recorded in the Environmental Administration's Järviwiki through the Havaintolähetti service, the browser version of which also works on a phone. Observations can also be reported to local environmental authorities, from which the information is forwarded to the national algae monitoring. On the Järviwiki website, you can also familiarize yourself with the blue-green algae observations made by others.

Observation transmitter (jarviwiki.fi)

For more information:

Poison Information Center  

Institute of Health and Welfare THL

Social and Health Supervision Agency Valvira

Lake and sea wiki