For decades, a factory operated by National Lead cranked out paint and pollution on a 400-acre plot of land along the Raritan River in Sayreville, in the shadow of the Driscoll Bridge. The factory is long gone and the land, now vacant, has become a target for potentially lucrative redevelopment.

North American Properties, a national developer, now owns the land and plans to build a mixed-use community called Riverton. The plan promises to essentially build a small town along the river from scratch, with 2,000 residential units and retail businesses anchored by Bass Pro Shops and other national chains. The Riverton plan has been around for years, and previous development plans for the site came and went before.

That nothing has been built yet is due in part to the complex environmental cleanup first required. Now, state officials say that cleanup is largely done and the land is ready for construction to begin.

At a news conference Monday, officials touted the effort as a prime example of how environmental responsibility is good for business.

“By promoting environmental health, we promote our economic health because the two are so inextricably linked,” said Shawn LaTourette, commissioner of the state Department of Environmental Protection.

But environmentalists say more remediation is needed. NY/NJ Baykeeper sued National Lead, state regulators, local leaders and multiple developers in 2009 to try to force a cleanup of the pollution that remains at the bottom of the Raritan River. That litigation is ongoing.

“Here we are about to have thousands of new residents and customers coming into these stores and into the area. And yet we still have a river that has not even begun to be remediated from the heavy metals and the sulfuric acid and other waste,” Greg Remaud, CEO of the NY/NJ Baykeeper, said.