Speak up now, or forever hold your peace.

After three months, the public comment period for the Environmental Protection Agency’s (EPA) proposal to list the Newtown Creek for Superfund cleanup is coming to a close.

It ends officially on December 23, though sometimes the EPA extends the comments period. The agency has not indicated it will do so in this case.

Once all comments are in, EPA official Walter Mugdan said it will likely take at least a year before a decision on the federal government’s proposed project, to clean the polluted industrial waterway, is announced.

Mugdan largely ruled out any alternative cleanup proposals, saying an environmental cleanup this large could only be handled by a state or federal agency. The state Department of Environmental Conservation is already working with Exxon Mobil on improving the creek’s water quality. The EPA Superfund project would address sediment contamination.

If the site is placed on the National Priorities List, making it eligible for a comprehensive so-called Superfund cleanup, that would trigger a complicated series of steps before work on the creek could begin.

First, the EPA would complete a Remedial Investigation and Feasibility Study to determine pollution levels in the creek and possible cleanup alternatives, said EPA official Angela Carpenter.

That process alone - which involves the collection of significant amounts of data and its analysis - would take three to five years, she said.

“This is a very extensive study,” Carpenter said. “This is not something you can go out and do in six or nine months.”

Once the study is finished, the EPA would spend another two years deciding on a cleanup plan before issuing a record of decision, she said. After that, the actual cleanup could begin.

Mugdan said a timetable for the cleanup is in the “15 to longer years range.” Though it will take a long time, he added, now is the best time to start the process.

“It will never get done if it never gets started,” he said.