The maps, released this week by the Federal Emergency Management Agency, are the first new ones in more than two decades, The Star-Ledger of Newark reported. They greatly increase the area believed to be at risk.
Bill McDonnell of FEMA's office of external affairs said they are only advisory.
"These are decisions communities are going to have to make together," McDonnell said. "All we're trying to do is provide them with the best data available, and we certainly hope townships use this information to enhance their existing ordinances and rebuild smarter."
FEMA said maps showing where flood insurance is required will be released in the next few months. But the advisory maps suggest living on the coast could become far more expensive with stronger construction or elevated houses required to avoid sky-high premiums.
"When we rebuild, we have to make sure we're not putting people in harm's way. This should really be the foundation for that," said Jeff Tittel, executive director of the New Jersey Sierra Club.