Harmful Algae Blooms

Current Toxic Algae Updates on the
Columbia River

Update: August 29, 2025

Labor Day Weekend Report for Recreational Waterbodies in Benton/Franklin Counties

Water samples were collected on 8/25 from the Columbia River at multiple locations. All samples were below recreational thresholds for anatoxin-a EXCEPT Howard Amon Park. At Howard Amon Park there were visible algal mats (see photo and video below) present. These floating mats can have high concentrations of algae toxins. A portion of one of these mats was sampled and contained 9.34 ug/L of anatoxin-a. This level exceeds the recreational standard (1 ug/L). “Warning” signs have been posted along the shores of Howard Amon Park. All shorelines of the Columbia River in the Tri-Cities could potentially have these floating mats and the amount of mat material can vary from day to day as river flow changes. Those at highest risk at becoming ill are young children and dogs that may ingest these mats.

Other Water Bodies in our Area

Scooteney Reservoir (North Franklin Co). Tested on 8/25. Microcystins (MC) were detected but BELOW the recreational threshold for MC (8 ug/L). MC concentrations could potentially increase over the long weekend.

Lyons Ferry State Park (Snake River). Some blooms have been present but samples taken on 8/25 NO MCs were detected.

Sacagawea State Park (Snake River). No blooms present. Not tested recently.

Charboneau and Fishhook Parks (Snake River). These parks are not in Benton-Franklin County. Contact Walla Walla Health for information or refer to statewide map (below) In general, massive algae blooms have been site on the Snake River downstream of Clarkston, WA. So far, the bloom has not impacted the Snake closer to the Tri-Cities.

Yakima River. Historically, the Yakima has not had detectable levels of algae toxins and is not monitored on regular basis.

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