A: Blue green algae, or cyanobacteria, can multiply quickly in lakes with high nutrient levels, particularly when the water is warm and the weather is calm. ... Blooms can spontaneously disappear or move to different parts of a pond or lake.

How long does a blue-green algae bloom last?

Blooms may last days, weeks, months or all year, and can even grow during winter when water may be covered in snow or has turned to ice. It is important to note that after a bloom has ended cyanobacteria can still persist in the water.

What makes blue-green algae go away?

Some bloom-forming types of blue-green algae produce toxins. When toxic blooms die and decay, toxic chemicals may be released into the water. Most toxins are degraded within 2 weeks, but can be in the water at low levels for many months after a bloom forms.