Sonoma County warns of toxic algae in local rivers

The gooey clumps of algae floating in some of Sonoma County’s rivers and creeks have prompted officials to post signs warning visitors that the slime could be toxic.

Signs went up over the past week along the Russian and Gualala rivers and at Salmon Creek.

Water quality tests at all three sites confirmed the presence of a species of cyanobacteria, commonly known as blue-green algae, that can produce toxins, said Rich Fadness, an engineering geologist with the North Coast Regional Water Quality Control Board.

The tests showed extremely low levels of toxins in the algae, Fadness said, but officials “posted educational sings so that people know what to look for.”

Signs along the Russian and Gualala rivers warn that “toxic algal mats may be present in this water,” with images of the floating slime.

At Salmon Creek, alert signs say that “toxic algal mats ARE present.”

The notices represent a new approach for water quality monitors in Sonoma County, Fadness said. In previous years, warning signs have gone up along the Russian River and other sites in response to dangerous levels of toxins. This year, officials are posting signs before there’s a major health risk, Fadness said.

“The water itself is safe,” Fadness said. “Swim in it. Enjoy it. Have a good time. But if you see large mats of algae, it’s best not to play in that.“

Water monitors found a higher concentration of algae at Salmon Creek, which prompted the more urgent alert signs there, according to Fadness.

People who signed up with River’s Edge Kayak and Canoe Trips in Healdsburg for a float down the Russian River with their dogs got an email from the company this week asking them not to bring canine companions along because of the algae signs.

River’s Edge has sent out similar notices over the past several years in response to algae warnings, said Manager Rochelle Collier.

The company has offered to reschedule or refund bookings for groups that can no longer make the trip because they planned to bring dogs, Collier said.

Typically, customers are “grateful to us for letting them know when we find out about the algae,” Collier said.

In 2015, a dog died from ingesting blue-green algae in the Russian River, according to Fadness. It is the only known case of a dog dying from toxic algae in the water there, he said.

Toxic algae can be green, blue, yellow, red or brown, said Christine Sosko, Sonoma County’s environmental health director.

“Sometimes the bloom is easily visible, forming a scum or discoloration on the water surface,” Sosko said. “Other times it is less visible, floating beneath the surface or on the bottom of a water body.”

Symptoms can show up within 48 hours after a person is exposed to water with toxic algae, Sosko said. They can include sore throat, congestion, coughing, wheezing, difficulty breathing, rash, diarrhea, vomiting, headache and abdominal pain.

Children and dogs are most susceptible to serious health effects from the algae, according to a press release issued Tuesday by state and county officials.

In addition to staying away from algae in the water, officials recommend rinsing off with clean water after playing in the rivers or creek and keeping an eye on children and pets, according to the release. Officials are urging people to rinse off fish caught in the water and to avoid eating shellfish if toxic algae is present.

You can reach Staff Writer Matt Pera at On Twitter @Matt__Pera.

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