SAN JOAQUIN COUNTY (KPIX 5) — The state of California is declaring an emergency over a non-native species of rodent being seen with increasing frequency near the San Joaquin Delta.

Wildlife teams are being deployed to battle a type of giant river rat called nutria.

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Originally from South America, the large, 20-pound rodents were first spotted in Central California about a year ago.

But now, for the first time, the animal has been found west of Stockton in the heart of the Delta.

The giant rodent moving into new territory and creating concerns for state officials.

Nutria are capable of destroying roads, levees and wetlands.

“Would you call this frightening? I would call this frightening,” said Peter Tira with the California Department of Fish and Wildlife.

He says the department has launched an emergency response that he termed “serious.”

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“Its an emergency response very similar to what we do in a wildfire or earthquake or flood. That just gives you a sense of the severity that we believe this is a threat to California,” said Tira.

Nutria live in or near water and can be very destructive. The big concern is that the rodents start destroying wetlands in the Delta and dig burrows that can weaken levees, roads and flood control projects.

A team of biologists has been trained to trap the nutria. And it can difficult to tell the difference between nutria and non-threatening animals like beavers, otters and muskrats

“It’s tricky to identify them. We have wildlife biologists, PhDs out there trying to understand and identify them. It’s been challenging,” said Tira.

Nutria are about two and a half feet long with a twelve inch tail. Their whiskers are white and their hind feet webbed.

Once full-sized, they can become pregnant again within 48 hours of giving birth, having litters of a dozen or more.

“It’s a triple threat. It’s public safety, it’s the economy, it’s the environment. If nutria get established in California, there’s almost no hope of removing them. That’s why we are acting so quickly.”

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Louisiana has also battled a much larger nutria invasion. But as to how the rodents ended up in California, nobody is quite sure.

Juliette Goodrich