Sonoma County public health officials are urging caution while swimming in or being near the Russian River after tests this week revealed the presence of a harmful toxin produced by blue-green algae near four public beaches.
Officials are not advising people to avoid swimming in the river — at least, not yet. But they are asking people to take precautions, especially with children and pets. Both are more susceptible to being harmed by the toxin.
“I think it would be better not to bring the dog to the river,” Dr. Karen Holbrook, the county’s deputy health officer, said Thursday. “If they do bring a dog, they need to monitor him or her very closely.”
The warning was issued after tests revealed the presence of Anatoxin-a in the water near the four beaches. The naturally occurring toxin attacks the central nervous system of mammals and can be so lethal that it’s earned the scary moniker “VFDF” — short for “Very Fast Death Factor.”
Under new state guidelines, any amount of the toxin found in waterways is enough to trigger health warnings. Officials began putting up signs Thursday at all ten of the Russian River’s public beaches encouraging people to be mindful of the algae and to follow recommendations to minimize risks from exposure.
The suggestions include not ingesting river water or using it for cooking, keeping pets and children away from algae and showering with fresh water after getting out of the river.
Holbrook said tests this week revealed “very low levels” of the toxin in the water at Steelhead, Forestville Access, Monte Rio and Patterson Point beaches. She said the highest detectable amount of the toxin was reported to be .23 parts per billion.
At 100 times that amount, or 20 parts per billion, officials would recommend that people avoid swimming in waterways altogether.
“It’s a big jump,” Holbrook said. “Could it happen next week? I don’t think so. But I can’t predict the future.”
County health officials are testing the river water weekly and updating results.
Last summer around Labor Day, a golden retriever dog died at the Russian River after it consumed lethal amounts of Anatoxin-a while on a rafting trip with its owners. Two more dogs subsequently succumbed to toxic algae, one on the Russian River and another on the Eel River in Mendocino County.
The deaths renewed attention on toxic algae. Holbrook said tests of Russian River water conducted around the time of the golden retriever’s death revealed levels of Anatoxin-a as high as 48 parts per billion, more than double the amount that would trigger an advisory for people and animals to avoid swimming in the river under updated state guidelines.
Dogs are particularly susceptible to the toxin because they tend to ingest water while swimming and also through grooming. They often slurp up algae while playing in the water.
The State Water Resources Control Board recently issued a similar warning about toxic algae for the entire North Coast, noting that high temperatures and continuing drought conditions increase the likelihood of potentially lethal algal blooms in area streams, rivers and lakes.
Blue-green algae occur in many water systems, typically where still, warm, shallow and high-nutrient conditions prevail. The algae tend to collect in mats or scums near the water’s edge, mixing with other, harmless green algae. Ingesting the algae can release toxins that can cause a variety of symptoms, including irritation of the eyes, nose, mouth and skin, gastrointestinal symptoms, muscle tremors, seizures and difficulty breathing.