Milky liquid flowing through NJ city’s waterways is not harmful, but its source is unknown, the mayor says

A milky substance the consistency of paint that flowed through the waterways of a Passaic County town on Wednesday is not harmful. But officials aren’t sure where it came from.

“It has been determined that the substance poses no immediate danger — either to airborne residents through fumes or to wildlife in the area,” Passaic Mayor Hector Lora told NJ Advance Media on Thursday.

A local resident walking through Third Ward Memorial Park around 12:50 p.m. noticed the creek turning white and reported the find to Lora.

Lora said he notified city health officials and went to the park to see for himself. “Probably within half an hour we saw a very drastic color change in the water,” Lora said, calling it “white with a blue tint.”

The substance contaminated Hughes Lake, a large pond that empties into McDonald’s Brook and empties into the Passaic River. The contamination was only visible in a small portion of the river but filled the city’s waterways, Lora said.

Inspectors from the New Jersey Department of Environmental Protection tested the water and found a pH of 6. Lora said a pH of 7 is more normal for the water.

But the DEP found the water to be free of toxins, including petroleum and other pollutants, the mayor said. “It wasn’t a solvent, it wasn’t inert and it didn’t react with water,” Lora said.

Lora said the substance that caused the water’s color change likely came from a chemical called “diatomaceous earth,” which is used in pool filtration systems. Based on the amount of chemicals found, the emptied pool was likely industrial size, Lora said.

A review by the local YMCA found they hadn’t flushed their pool’s filtration system in two weeks, the mayor said. A check of wells in the city showed the chemical had flowed into Passaic from nearby Clifton, he added.

Lora said the person or company responsible for the contamination could face serious penalties.

“Even though it’s safe, and it wasn’t, it’s still illegal to dump any substance or material into any body of water, down a gully or manhole or anything like that,” Lora said. “We will continue the investigation.”

City officials slowly flushed the waterways Wednesday afternoon and evening, and by early Thursday the water was clear again, Lora said.

“It’s visible away, you can’t even spot it in the water,” Lora said. “But we will continue to monitor it.”

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Anthony G Attrino can be contacted at [email protected]. Follow him on Twitter @TonyAttrino. Find NJ.com on Facebook.