RINGWOOD - A probable carcinogen could threaten the Wanaque Reservoir if a system isn't built to decontaminate groundwater and brooks from contamination at a nearby Superfund site, according to NorthJersey.com

The Wanaque Reservoir, the second largest in the state behind the Round Valley Reservoir in Hunterdon County, provides drinking water to 3.5 million people.

A chemical known as 1,4-dioxane believed to be coming from the Ringwood Superfund site has been detected in high levels over the past 18 months in groundwater and brooks that feed the reservoir, NorthJersey.com reported.

A report prepared for the reservoir's operator, North Jersey District Water Supply Commission, suggests that a system be built to pump contaminated groundwater to the surface and decontaminate it to prevent the pollution from reaching the drinking water supply.

The contamination was discovered at a Superfund site where Ford Motor Co. dumped toxic paint sludge 50 years ago, the report said.