The U.S. Environmental Protection Agency has added New York City’s Newtown Creek to its Superfund list, which prioritizes cleanup and remediation efforts for the country’s most hazardous waste sites.

The 3.8-mile-long Newtown Creek, which runs along the border of Brooklyn and Queens, was found to be contaminated with polychlorinated biphenyls (PCBs), volatile organic compounds (VOCs), pesticides and metals. One of the most active industrial areas in New York City was adjacent to the creek for many years.

This is the city’s second site assigned to the Superfund List. Brooklyn’s Gowanus Canal was added in March.

The EPA says the evaluation and eventual cleanup will focus on the sediments in the creek while also identifying additional sources of pollution, including the 1978 Greenpoint oil spill, which contaminated nearly 100 acres of the creek with an estimated of 17 million gallons of oil.

“The toxic pollution of Newtown Creek is more than a century in the making,” says Judith Enck, the EPA’s regional administrator for New York and New Jersey. “[It] is a key urban waterway.”

Newtown Creek makes up part of the core area of the New York-New Jersey Harbor Estuary, designated by the EPA as an “estuary of national significance.”

The New York City Department of Environmental Protection has supported the addition of Newtown Creek to the Superfund list, though the city challenged that same designation for the Gowanus Canal, chiefly because of the canal’s proximity to areas that were in talks to be developed for commercial and residential purposes.

The EPA says it does not have a timetable for the cleanup but added that negotiations are underway to award additional contracts to evaluate the site.

The agency also would not confirm the cost of the cleanup but said the 15-year/ $300 to $500 million estimate for the Gowanus Canal site could be considered “very rough estimates” for Newtown Creek.