About Toxic Algae
Toxic algae bloom in Harts lake
Cyanobacteria, also known as blue-green algae, are bacteria which have some of the characteristics of plants. Cyanobacteria are found throughout the world on land and in lakes, rivers, and ponds, and in estuaries and seawater (oceans).
Cyanobacteria often form blooms when the conditions are favorable. Blooms are often seen in standing water in lakes, ponds, ditches, lagoons, or embayments of rivers. Because many cyanobacteria species can regulate their buoyancy, they often rise to the surface of the water to form a surface scum. A scum is a thin oily-looking film that can become several inches thick (and can sometimes look like spilled paint). When conditions are good for a bloom, a lake or pond can change from clear to turbid within just a few days.
Toxic algae bloom in Shadow Lake
Most cyanobacterial blooms occur during warm summer and early fall months but in Washington, toxic blooms also occur during colder winter months. For example, American Lake in Pierce County has a history of toxic episodes during the winter at low water temperatures (7-8°C). It is possible that a bloom can be found somewhere in Washington nearly every month.
Acknowledgements
Most of the above information is from "Toxic Cyanobacterial Blooms - A Field/Laboratory Guide". Dr. M. A. Crayton, Pacific Lutheran University, Tacoma, WashingtonWashington Department of Health. Used with permission.
For more information please see:
EPA Harmful Algal Blooms
WA State Freshwater Algae Control Program
WA State Department of Health
Photo credit for Maple Leaf on algae scum (banner photo) belongs to Bruce Andre Photography