Toxic algae is once again showing up at a popular park in Richland, Washington. Health leaders are warning people to keep their dogs out of the water.
The Benton-Franklin Health District has found elevated levels of harmful cyanotoxins at Howard Amon Park. They started testing water at multiple recreational sites and water treatment plants each year. That was after several dogs died in 2021 after playing in the river.
Jim Coleman is a climate specialist with the Benton-Franklin Health District. Dogs are especially susceptible to the neurotoxin, he said, and should stay out of this stretch of the river. The toxin can also affect small children.
However, as long as adults stay away from the mat-like chunks of algae, which can also be weighed down with other aquatic weeds, it should still be OK to recreate in the water, Coleman said.
“Most people that are recreating and swimming won't ingest any water, whereas dogs have a tendency to drink a lot of water when they're swimming in the water. And, I think they have a tendency to sample things that are floating on the surface,” he said, noting that he would continue spending time in the river.
The health district has placed toxic alert warning signs along the banks of Howard Amon Park.
This particular type of benthic algae grows on rocks at the bottom of the riverbed. Known hotspots about 50 miles up the Columbia River, near the Vernita Bridge, Coleman said.
“Benthic algae is not very obvious and can be growing on the rocks and not producing toxins,” he said.
However, when the algae gets old, it lifts off the rocks.
“Sometimes that's exacerbated by extreme heat or if the water drops,” he said.
The algae is buoyant and floats downstream, often forming large mats that are very high in cyanotoxins. Those mats tend to get caught in a big eddy at Howard Amon, which pulls the floating debris to the shoreline.
After seeing years of fluctuations in the toxins at the park, Coleman said he isn’t sure if they’re seeing more because they are now monitoring the area or if the elevated levels of toxins are happening more frequently.
The Snake River has also experienced several toxic blue-green algae blooms.
However, he said, warmer water temperatures and droughts with lower water flows can lead to conditions that are ripe for microbial growth, like cyanobacteria that produce the neurotoxins.
“These organisms are photosynthetic, so anything that hinders sunlight getting to them would hinder their growth,” Coleman said.
Now, the health district is staking a device into the Columbia River to help monitor the toxins, more than just with surface water samples. The SPATT devices have a chemical resin inside a mesh bag that binds to the toxin as it floats in the water.
“ We'll leave that out for a week, and then it gives you kind of a snapshot of what's happening,” he said.
But the devices can’t tell when there are peaks of the toxin in the water, Coleman said.
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