Cyanobacteria Blooms

Cyanobacteria, also known as blue-green algae, are not actually algae. They are a type of bacteria that can “bloom” like algae when the conditions are right. Cyanobacteria blooms can be a variety of colors, such as bright green, blue-green, white, red or yellowish-brown. The water may look like pea soup or the surface may look as if paint has been spilled on the water. They may or may not have thick scums or foam. As the cyanobacteria begin dying and decomposing they may release an unpleasant odor similar to rotting plants.

Lakes and ponds are the most likely waterbodies to experience blooms, but they also can occur in streams, especially if they are slow moving or pooled. Many cyanobacteria can sink or float to control their location in the water column, so a bloom can appear to move and change quickly. Other factors, such as wind, rain, wakes from recreational activities and currents, can also affect the location of a bloom or how it appears. The photo gallery below shows examples of typical Missouri cyanobacterial blooms.

Reporting

So how do you know if a bloom is cyanobacteria or not? Unfortunately, you cannot tell if an algal bloom is harmful or not just by looking at it. If you believe you have observed a potentially harmful algal bloom, please report the bloom. For general information about harmful algal blooms, visit the department's Harmful Algal Blooms (HABs) webpage.