California is under invasion from a 20-pound rodent once believed to have been eradicated from the state – and officials now fear humans may be to blame.

The California Department of Fish and Wildlife said DNA testing of the 2.5-foot-long pest, known as a nutria, shows the current population is linked to animals in Oregon, not to the species that roamed California in the 1970s before being wiped out.

“This study supports our long-held belief that the current invasion is the result of reintroduction rather than explosive growth of a remnant, undetected population,” the CDFW ‘s Nutria Eradication Program Manager Valerie Cook said.

Nutria are semi-aquatic rodents native to South America that live near freshwater and estuaries. Because they burrow like beavers, they can cause extensive damage to water infrastructure, banks and levees, posing a hazard to people, livestock and machine operators, according to the agency.

The semi-aquatic rodent comes from South America. wildlife.ca.gov

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The species is classified as an A-rated pest.

The big question now is why – was it accidental, or something more nefarious?

“Given where nutria were rediscovered in California, it is nearly impossible that they could have migrated there on their own,” Michael Buchalski of the CDFW told SFGATE.

“It’s too far of a distance and we don’t find any nutria in the areas in between. That makes human introduction the most likely scenario.”

“Someone may have thought they could be an effective natural way to manage aquatic vegetation on their private property,” Buchalski added. “Also, some people just really like nutria… Or it could have been malicious in hopes that they would cause environmental damage. It’s hard to know.”

To test the theory, researchers carried out extensive DNA analysis after pregnant nutria were discovered in Merced County in 2017 – the first confirmed presence in California in decades.

The pests destroy the wetlands, agriculture, and flood control infrastructure in the state. Getty Images

The Nutria was found in Merced County in 2017, before that they were wiped out in the state. San Francisco Chronicle via Getty Images

Officials initially considered whether the animals were linked to a long-hidden remnant population in the state that had gone undetected.

Researchers collected skins and skulls from museums and universities across California, including a taxidermy specimen from Butte County, and compared them with nutria populations across the U.S. and worldwide.

In the end, CDFW said “genetic research suggests California’s current nutria invasion was the result of intentional reintroduction, with the original source animals likely being transported from the central Oregon population.”

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Nutria were widely introduced across the globe in the late 19th and early 20th centuries for the fur trade. When demand collapsed, many were released into the wild, including in California, where the species was declared eradicated by the late 1970s.

Since 2017, officials have launched a massive effort to eliminate the destructive rodents, which damage wetlands, agriculture and flood-control systems. A total of 7,841 nutria have been removed from the Sacramento-San Joaquin Delta and Central Valley as of the end of March.

The Post has reached out to the CDFW for further comment.