Cyanobacteria, also known as blue-green algae, are bacteria which have some of the characteristics of plants. They are found throughout the world on land and in lakes, rivers, and ponds, and in estuaries and seawater (oceans). Thought to be caused in part by global warming, all over the world, more and more water bodies are seeing large areas of growth or algae blooms. These blooms are important because the bacteria produce toxins that affect water quality, ecosystem stability, surface drinking water supplies and public health.  

During early fall of 2021, portions of the shores of the Columbia River that flow through the Tri-Cities area (Richland, Kennewick and Pasco) were closed after the deaths of several dogs who had been exposed to toxic algae while along the shoreline.   

In Benton and Franklin Counties, BFHD was aware of this issue occurring in local lakes and rivers. What made this incident in 2021 unique was that toxin-producing blooms had not been found in the flowing waters of the Columbia River.  Of concern was that the area in which the blooms appeared to be occurring was the same area where the cities of Richland, Kennewick and Pasco have water intakes for their drinking water treatment facilities. BFHD works closely with these utilities to make sure that the drinking water is safe.

While not all algae blooms produce toxins, but there is no easy or quick way to know if a bloom contains harmful toxins. Activities that can expose you to toxic algae are swimming, boating or fishing. During these activities, exposure to toxic algae typically occurs when the toxins are swallowed, or one inhales water spray with the toxins.  By far, swallowing is the most common way to be exposed. 

Is it safe to eat fish from rivers and lakes that have algae toxins in it? Click here to learn more.

Current Toxic Algae Updates on the Columbia River

Update:  July 24, 2024

Increased air and water temperatures continues to create a situation that typically favors the growth of algae in the Columbia River. The last water sampling event was on 7/22/24.  No algae toxins were detected at the water treatment plant intakes.  There was toxin detected at Leslie Groves Swim Beach and Howard Amon Parks in Richland. However, the amount of toxin was below the threshold for recreational use. The anatoxin-a concentration at Leslie Groves was 0.37 ug/L and the concentration at Howard Amon was 0.28 ug/L.

We are beginning to move into the worst time of the year (Aug-October) for production of algae toxins.  BFHD would like to remind users of the rivers to be cautious when swimming in the river and if green material is floating on the surface, it is safest to stay out of the water.  Dogs are most at risk as they have a tendency to ingest large amounts of water and also ingest green material along the shoreline.

The next sampling event will be on 8/12/24.


Full Recap BFHD Harmful Algae Bloom Season Recap (

BFHD always urges dog owners to be cautious when visiting a shoreline with your dog, follow these guidelines if your dog goes in the water: 

    • Do not let them eat or chew on clumps of algae
    •  Do not let them lick their fur
    •  Rinse them with clean water after swimming
    •  Rinse your hands and any exposed skin 


Animal Safety Graphic
Toxic Algae Warning Spanish

Toxic Algae Warning  Lake Closed Sign

No other sites are showing levels of concern. We will continue to keep you updated.

When in Doubt, Stay Out!

Visiting a Lake? Click on the picture to learn the Toxic Algae Status.
Washington State Toxic Algae Map
Toxic Algae Poster
Toxic Algae Poster
(Click photo to download pdf file)