The pipe carries waste-water from Duke Energy in Eden, N.C. - a coal power plant still reeling from a Feb. 2 pipe failure that dumped up to 39,000 tons of toxic coal ash into the same river. Arsenic levels in the waste-water are 14 times those considered safe for human contact.
"Because the Duke Power-Eden coal ash spill is located in North Carolina's portion of the Dan River, a potential hazard exists immediately downstream of the release," health officials said in a statement, recommending that people "avoid recreational contact with water and sediment in the Dan River in North Carolina downstream of the Duke Power-Eden spill site."
Residents are urged to avoid contact with coal ash along the river bank and immediately wash any skin exposed to water or sediment with soap and water. Health officials also warned against eating fish or shellfish from the contaminated river.
Drinking water in the area is safe, health officials said.
Arsenic is a naturally occurring chemical tied to skin, bladder and lung cancer, according to the U.S. Centers for Disease Control and Prevention. It can also cause nausea and vomiting, blood vessel damage and abnormal heart rhythms.
In children, arsenic exposure has been linked to lower IQ.
The Associated Press contributed to this story.