HOLLISTER • Beware the water in Salmon Falls Creek Reservoir, where potentially toxic blue-green algae now grows, health and environment officials warn.
This is the first time that a laboratory test confirmed the toxin’s presence in the reservoir and the first time such a warning has been issued.
Such algae is present in nature, but this batch is starting to produce toxin due to a perfect combination of elevated phosphorous and maybe higher nitrogen in a low level of warming, slow-moving water, said Sonny Buhidar, the regional water quality manager for the state Department of Environmental Quality.
“It’s not just the nutrients,” he said. “There’s a number of factors. You’re going to find blue-green algae anywhere in nature. The number of species that produce the toxin, it’s very small. It just so happens we have this one here.”
The algae tends to hug shorelines, encouraged to grow by wind lapping the water and mixing it with soil and sand, Buhidar said.
So people who are boating or fishing should be especially careful not to let their children and pets splash around and drink the water by the shore.
The bacteria has been known to kill dogs and sicken people.
A blue-green algae also was blamed for killing several dogs along the Snake River in the Burley area in 2000.
In addition, anyone who eats fish from the reservoir should remove all fat, skin and organs before cooking, since that is where toxins are most likely to collect, said Craig Paul, environmental health program manager for the South Central Public Health District. The toxin cannot be removed by boiling the water.
The DEQ issued the warning after laboratory testing earlier this week showed more than 500 parts per billion of the aphanizomenon neurotoxin.
The DEQ went back out Friday, and the falling temperatures seem to be helping.
Buhidar said much of the algae is clumping and dropping to the bottom.
As it gets colder, the algae will go dormant and the toxins will wash downstream, said Paul.
“As soon as the temperature starts to get cooler, things start to break apart,” Buhidar said.
If water levels increase, that will help too, as it would dilute the toxin concentration.
The DEQ will continue monitoring and testing the water. The warning will be lifted once the levels fall to fewer than 20 ppb.
The aphanizomenon, a genus of cyanobacteria, can cause neurological symptoms such as muscle spasms and difficulty breathing, says a news release from the Health District.
Children and pets are particularly at risk.
The Panhandle Health District issued a similar warning last month for Fernan Lake, in northern Idaho.