What You Need to Know About Blue-Green Algae

During hot weather conditions, the production of harmful algae blooms can increase, thereby perpetuating more harm to both humans and pets alike (2)(3). 

But what exactly are blue-green algae? 

First off, they are much different from the conventional algae. Blue-green algae occur naturally in any aquatic body as a form of photosynthetic bacteria known as cyanobacteria. These types of bacteria are mostly found in still waters and undergo a rapid reproduction process in the presence of abundant nutrients and high temperatures (1). Under these conditions, they can reproduce rapidly to form “algal blooms.” 

Blue-Green Algae: How to Identify Them 

In most cases, blooms appear like pea soup or cascaded green paint, with smaller structures and density. When enough grows, they tend to cover certain parts of the water body they inhibit, showing traits of visible algae (3).  

Do They Happen Naturally? 

Although algal blooms are very common in our water bodies, they don’t just appear without a determining factor. They occur mostly as a result of some environmental conditions and human-induced pollution in our water bodies (1). Some fertilizer components, such as nitrogen and phosphorus, can find their way into our bodies during a surface runoff (3). This leads to an overwhelming increase in the algae population within the affected water body. It also creates an environment that will make them thrive. At this point, they become clearly viable and toxic enough to impact the aquatic ecosystems as well as human health negatively. 

Usually, you will find algal blooms in Minnesota lakes during warm weather condition indexing as much as 75°F. Nevertheless, it is possible to see them during any other time of year – even the winter (3). 

Harmful Effects of Blue-Green Algae 

An excess population of blue-green algae can disrupt the water’s ecosystem, which will eventually lead to the production of harmful toxins.  

Ingesting, having body contact with, or inhaling water droplets containing algal blooms can make you sick. When this occurs, you will experience nausea, rash, skin irritation, sore throat, or cough (3).  Generally, it takes anywhere between two hours to two days after contact before these symptoms will begin to manifest. However, animals can begin to show signs of sickness after some minutes of exposure to blue-green algae infested water (3). 

Controlling the Spread and Effects of Algal Blooms in our Water Bodies

Truth is, we can’t expunge algal blooms from our water bodies completely. They are an integral part of the algal family, and as such, water bodies are their homes. Nevertheless, they can be controlled. 

Understandably, it is impossible to control the temperature of these lakes, but we can help monitor the amount of nutrients going into it. 

We should always properly dispose of organic materials and other debris and prevent them from washing off into our water bodies (1).  

Additionally, reducing the amount of man-made nitrogen and phosphorus in the form of lawn fertilizers, feedlots, cultivated fields, and the likes will go a long to help curb the adverse effects of algal blooms in our water bodies. Though the results might not be immediate, the long term solution would be worth it after some time. 

Finally, caring for our water bodies requires a collective effort from every member of the community. By stopping the spread of blue-green algae in their tracks, we can help restore the ecological balance and natural beauty of our water bodies. 



(1) https://dnr.wi.gov/lakes/bluegreenalgae/

(2) https://www.sciencedirect.com/topics/earth-and-planetary-sciences/blue-green-algae

(3) https://www.pca.state.mn.us/water/blue-green-algae-and-harmful-algal-blooms