Harmful Algae Blooms

Algae Toxin Test Results

Update: August 18, 2026. Situation has been UPGRADED

Floating debris continues to persist at Howard Amon Park in Richland, WA. Additional samples of algae mats were taken yesterday and had very high amounts of anatoxin-a. The situation has been updated to “Warning”.

Under “Warning” conditions DO NOT let children or adults touch, swallow or swim near any clumps of algae.

DO NOT let dogs eat clumps of algae or drink from the water.

Please note that this warning is primarily for Howard Amon Park. However, there has been many floating debris in the Columbia River lately. Floating debris is an indicator that floating chunks (mats) of harmful algae could be present. Floating debris can occur at any time and place along the shore of the Columbia River during summer and fall and is difficult to predict when it may occur.

How to identify benthic algae mats.

1. Green filamentous algae. Typically, not toxic. Lime green, rough, sponge-like surface. Often has lots of trapped bubbles and floats on surface.

2. Aquatic plants. Has plant-like characteristics- stems and narrow leaf-like structures. Not toxic. Often floating in large clumps. Sometimes anchored to bottom.

3. Cyanobacteria mat (Toxic Algae). Can be TOXIC. Typically, smooth, dark green or brown. Not very thick. When disturbed in water it has undulating movement (like wet blanket on water surface). Can have trapped bubbles and floats on surface.

Updates will be posted here when new test results are available.

If you see what you believe is an algae bloom in a local waterway, you can report it to 509-460-4200 and we will investigate.

BFHD Sampling Sites Map

Background
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.

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