UKIAH (KCBS) – Tests are currently being conducted by the California Department of Fish and Wildlife and the UC Davis Veterinary Teaching Hospital to find the root cause of a mass die-off of carp at Lake Mendocino.

The U.S. Army Corps of Engineers is prohibiting swimming at Lake Mendocino. “Public safety is our number one priority,” said Mike Dillabough, chief of Operations and Readiness. “We’re taking these steps to maintain safety and so our visitors can enjoy full access of the recreational areas as soon as possible.”

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Swimming is prohibited at the lake until further notice, pending test results. Signs have been placed at Lake Mendocino access areas to notify the public.

Water and fish samples have already been sent to state laboratories and according to the Santa Rosa Press Democrat, the laboratory at UC Davis is testing for koi herpes virus.

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Koi herpes virus was first detected in the United State in 1998 and outbreaks have since been identified worldwide, that according to the UC Davis Veterinary Medical Teaching Hospital’s website.

The disease is suspected of killing thousands of carp near Bakersfield in 2010, Tulare County in 2009, and Clear Lake in 2008.

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The virus is not believed to be harmful to other fish or humans.