NEVADA COUNTY (CBS13) — A warning to swimmers: Stay out of the South Yuba River in Nevada County.

Nevada County officials issued a no swim advisory on Friday for the South Yuba River after preliminary tests show “dangerous levels of E. coli” in the water.

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Tests show a massive yellow containment plume with high levels of E. coli is floating along the water.  It’s a danger to humans and animals.

The advisory is issued from below Washington to Englebright Lake, including the lake.

County officials said the river has tested positive for twice the California Environmental Protection Agency’s safe recommended levels of E. coli, which has turned the river to a muddy yellow color.

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(credit: YubaNet)

(credit: YubaNet)

“E-Coli can make you pretty darn sick, so as an adult over 2 to 4 days you can develop flu-like symptoms,” said Melinda Booth with the South Yuba River Citizens League.

The cause of the contamination is currently under investigation.

It’s not known where this dirty water began, but investigators from multiple agencies are also testing for toxic metals such as arsenic, lead, and mercury.

“We’re not barricading anything on the state parks, but we are putting out the signs for people to stay out,” said Capt. Jeff Pettitt with the Nevada County Sheriff’s Department.

County officials said full test results will take 3 to 4 days to receive.

Investigators said until they know what this mysterious so-called “blob” is, the river is off-limits to everyone.

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