The California Department of Fish and Wildlife has identified the chemicals used in a firefighting operation that have been linked to a fish kill in Codornices Creek in Berkeley last week.
"The fire foam retardant used contained Alpha-olefin Sulfonate Solution, which can be toxic to the environment in very high concentrations," said Fish and Wildlife spokesman Peter Tira in an email.
On April 3, the Berkeley Fire Department responded to a fire inside a garbage truck on the 1600 block of Rose Street, a residential area. The firefighters doused the burning garbage truck with fire-retardant foam, which flowed into storm drains that emptied into the creek, killing at least 64 fish — 63 were identified as native steelhead trout, a threatened species.
"Firefighters noticed that flames threatened two large compressed gas cylinders on the truck and, recognizing the immediate danger to people and homes nearby, sprayed the garbage truck with Class A Firefighting Foam," Mitch Buttress, environmental compliance specialist with the city of Berkeley, said in a statement. "As this was a fast-moving emergency response situation with an explosion hazard, firefighters followed protocols to first protect life."
Officials said that firefighters didn't have time to cover storm drains to prevent fire retardant from heading into waterways.
Tira said the state agency collected 48 of the dead fish for lab analysis.
"We got the composition of the fire retardant, and there certainly was toxic elements within that. So that's what's linked to the fish death," said Tira. "There likely were some other toxins that came directly off of the fire on the garbage truck that may have washed into the creek as well. So it's pretty apparent to our scientists the cause of death."
Tira said the product had been extensively tested and classified as "biodegradable" and should not present long-term environmental impacts.
Local organizations and community members have worked to restore Codornices Creek as wildlife and fish habitat over the past two decades. Although this is a setback, Tira said he expects the creek to recover.
"In situations like these, we always see firsthand just how resilient Mother Nature is, and so we expect this creek to make a full recovery," said Tira. "It's certainly an unfortunate incident, but it's a very healthy, fertile little creek and we expect to see it bounce back."
Tira said his agency would work with local fire departments to craft additional environmental precautions.
"It's a good learning experience for all of us," he said. "I think we'll all be more careful and have safeguards in place in the future to protect this, and other creeks, in similar situations."
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