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Algal Blooms are Harmful to Humans and the Environment

Algal blooms happen when algae – microscopic, plant-like organisms that naturally live in the water – grow out of control. The resulting blooms can look like mats floating on the water, or like scum, foam or spilled paint on the water’s surface. They can be brown, neon green, or blue-green, and can be smelly, slimy and even poisonous.

Rapid algal growth happens when nutrient levels, light, pH, and temperature are just right. But phosphorus is by far the most important ingredient in their development.

In many lakes, the amount of phosphorus in the water controls how big and how bad a bloom becomes. So the key to controlling blooms is reducing the amount of excess phosphorus that reaches the lakes. For instance, the phosphorus in Lake Erie comes from many different places, with the largest amount coming from agricultural lands. Phosphorus helps plants grow. This is a good thing for farmer’s fields, but too much of it is quite the opposite for the health of surrounding water bodies.

Blooms also have direct economic implications. Who wants to own property, spend vacation time, or play on beaches covered in slimy mats of algae? Blooms discourage people from enjoying the water which means fewer boaters, anglers, and beach goers – and less of the money they bring to shoreline communities.

Large algal blooms can make water unsafe for people and their pets, fish and wildlife. Harmful algal blooms, made of a particular type of algae that release a variety of liver, skin, and neurological toxins, can make swimming unsafe. Large blooms also disrupt the way a whole lake ecosystem works. When algae die and sink to the lake bottom to decay, they rapidly deplete the supply of oxygen dissolved in the water, creating “dead zones,” where fish and other aquatic life cannot survive. In extreme cases, this results in large numbers of dead fish washing onto shore.

Toxic algae is a human health concern. Research from Brain Chemistry Labs suggests a link between cyanobacteria, blue-green algae, and Alzheimer’s and Parkinson’s diseases. In 2014, 400,000 residents in Toledo, Ohio went without drinking water for three days. Over 100 people got sick during that time. 10% of water-related illnesses reported between 2013 and 2014 came from harmful algal bloom contamination in Ohio drinking water.

Annual Lake Erie Alive – Let Your Voice Be Heard!

As western Lake Erie continues to be plagued by annual—and sometimes toxic—algal blooms, Ontarians and Americans are being asked to join in a social media rallying cry for urgent action to protect the lake and, along with it, drinking water for millions of people. People can participate in this 4th annual social media event by sharing Lake Erie stories and photos on Instagram, Twitter, and Facebook with the hashtag #WeAreLakeErie to help create a virtual wave of support for the lake to demonstrate to decision-makers the important role the lake plays in the lives of so many people.


The event was created in 2017 by three Canadian environmental organizations: Environmental Defence Canada, Canadian Freshwater Alliance, and Freshwater Future Canada.