~ Questions and Answers ~

What are algae? Algae are a diverse group of organisms found both on land and in water. They vary from small, single-celled forms to complex multicellular forms.

What are blue-green algae? Blue-green algae are actually a primitive form of bacteria, more accurately called cyanobacteria.

What is an algae bloom? An algae bloom is a rapid and massive build-up of algae cells that imparts a blue-green, milky white or green color to the water. Sometimes blue-green algae can be further concentrated along the shore by wind and/or wave action.

Are all algae toxic? No. Only certain species of blue-green algae are capable of producing toxins, and even these species are harmless most of the time.

Where are toxic blue-green algae found? Potentially toxic blue-green algae occur in standing bodies of water exposed to the sun, e.g., lakes, reservoirs, roadside ditches and stockponds. They are not normally found in rivers, streams, springs, irrigation canals, or wells.

Can I become ill from being around a water body that contains a potentially toxic algae bloom? There is no health risk as long as you avoid contact with the water. Water containing an algae bloom should not be ingested because is may contain toxins which are potentially harmful. Skin contact with concentrated algae may cause irritation. However, other activities near the water, such as camping, dining, hiking and bicycling are safe.

What are the symptoms of toxic algae poisoning? Ingesting toxins may cause diarrhea, nausea, cramps, lethargy, sensations of numbness, dizziness, tingling and fainting. Skin contact may produce skin irritation and/or rash.

Children are at greater risk than adults because of their comparatively lower body weight.

All warm-blooded animals are susceptible to blue-green algae toxins, including people, pets, livestock, waterfowl, furbearers, game and non-game animals and poultry.

Is there an antidote? There is no antidote known to be effective in counteracting the effects of the toxin once it has been ingested.

What should I do if a person or pet swims or wades in water containing a potentially toxic algae-bloom? Wash the water and algae off of them using water from a public faucet or other safe source. Do not let pets drink the water or lick the algae off their body.

What conditions favor the growth of toxic blue-green algae? Potentially toxic blue-green algae prefer warm, calm waters that are rich in plant nutrients, especially phosphorus.

What conditions lead to blooms? Blue-green algae blooms can occur anytime from May through October, but they normally occur during the hottest part of the summer-June, July and August.

What does a bloom look like? A bloom of potentially toxic blue-green-algae can look like pea soup in the water or like green or blue latex paint along the shoreline. At times, a bloom can have blue-green, white or brown appearance. Blue-green algae are usually mixed with the near-surface water or appear as floating mats; they do not grow from the bottom as do mosses or other types of aquatic plants.

How do I know if a toxin is present? There is no way to tell for sure if the water is toxic without very specialized laboratory tests. Harmless strains of potentially toxic algae look the same as toxic strains under a microscope. A toxin imparts no distinguishing odor, taste or color to the water.

Can the water be treated to remove the toxin? Toxins cannot be removed with conventional treatment or disinfection. Boiling is also ineffective.

USDA Forest Service

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US Army Corps of Engineers ~ Portland District