How to Avoid Toxic Algae
Posted on 06/08/2023

Toxic Algae and Cyanobacteria

Summer is here for Benton and Franklin counties, which means that it's time to be on the lookout for harmful algae and cyanobacteria, also commonly referred to as toxic algae or blue-green algae.  

The Environmental Health Team at the Benton-Franklin Health District (BFHD), with the help of city partners from Kennewick, Richland, West Richland and Pasco, are testing 12 key areas along the Columbia River twice a month in the BFHD Water Lab. These key areas include recreation spots and nearby drinking water intakes for water treatment plants.  

If BFHD detects toxin levels above thresholds set by the state, then specific actions will be implemented to protect and alert the public.  
LEARN MORE ABOUT TESTING: Toxic algae testing stays local, thanks to new equipment (

About Toxic Algae & Cyanobacteria

Toxic algae and cyanobacteria are simple, plant-like organisms that live in water. In hot weather, toxic algae and cyanobacteria can quickly grow out of control (or "bloom"). Blooms sometimes look like foam, scum or paint on the water's surface. It can make the water appear different colors, including green, blue, red or brown. It's important to know that not all toxins are visible and can sometimes look clear but harmful algae can be below the water's surface.  

Blooms are more likely to occur when the water begins to heat up, is slow-moving and full of nutrients such as nitrogen and phosphorous (often when there is runoff from nearby fields). Effects of climate change, such as warmer weather, can also make blooms worse.  

How People and Animals Get Sick 

People, pets, livestock and wildlife can get sick when they have contact with food or water containing certain types of algae, cyanobacteria and toxins. Ingesting water that contains cyanobacteria can be deadly for pets and people.  

  • People and animals can get sick if they:
    • Swim, float or play in/near contaminated water 
    • Eat contaminated fish, shellfish or other foods
    • Drink contaminated water
  • Symptoms of exposure include:
    • Stomach pain, vomiting, diarrhea
    • Headache, fever, tiredness or other general symptoms 
    • Skin, eye, nose or throat irritation
    • Neurological symptoms (muscle weakness or dizziness) 

Animals can get very sick and even die within minutes of exposure/ingestion. It is critical that you seek immediate veterinary care for pets and livestock if they seem sick after being near a body of water. Animals are often the first affected because they are more likely to swim in or drink from bodies of water that could contain harmful algae. 

When in Doubt, Stay Out! 

  • You can take steps to protect yourself, your loved ones and your pets from getting sick from harmful algae and cyanobacteria: 
  • Check for swimming and fishing advisories and warnings before visiting lakes, rivers and oceans. Should harmful algae be detected in the water, BFHD will post "Warning, Keep out" signs on the shoreline and at the boat ramps. 

  • If you see an algal bloom, stay out of the water and keep your pets and livestock out of the water. You cannot tell if a bloom is harmful just by looking at it, the water needs to be tested by a lab, so it is best to use caution and stay away. Report it to BFHD immediately if you believe toxic algae is present.  

  • Do not fish, swim, boat or play water sports in areas with known harmful algae or cyanobacteria.  

  • Do not go into the water if it:

    • Smells bad 
    • Looks discolored 
    • Has foam, scum, mats or paint-like streaks on the surface 
    • Has dead fish or other animals washed up on its shore or beach 
  • If the community is notified that toxic algae or cyanobacteria are in a nearby body of water or your drinking water supply, follow local or state guidance to reduce your chances of getting sick. 

  • Check for and follow local shellfish and fish advisories before eating any fish or shellfish you collect. 

  • Follow BFHD's Facebook @BentonFranklinHealthDistrict and website,, for information and advisories. 

  • If you suspect toxic algae or see an algal bloom, contact the Environmental Health Team at BFHD 509-460-4205 or the Washington State Department of Ecology
  • If you plan to go fishing and you are concerned about toxic algae but want to eat the fish caught, remove the fat, skin and organs before cooking. For additional fishing tips during algae blooms check out the Oregon Department of Fish and Wildlife.