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: October 3, 2023

General Trend - Toxins decreasing below safe levels for people

BFHD has taken water samples from multiple locations along the Columbia River for the last two weeks. Toxin levels have decreased substantially; however, they do still pose a risk if water is ingested. Signs will remain posted along the shoreline at Howard Amon Park as that is a spot where algae has a tendency to accumulate. Most at risk are DOGS that could potentially ingest floating pieces of algae. BFHD will continue to sample river water for toxins over the next few weeks. If we detect toxin levels above recreational thresholds, we will post that information here.


BFHD highly recommends that you keep your pets away from the Columbia River shoreline in the Tri-City Area until temperatures drop significantly. Dogs are at risk because they ingest water when they swim and also have a tendency to ingest material along the shoreline.


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)