Yes, the Hackensack River is at sea level in Hackensack.
But if anyone thinks that sea level rise from global warming is going to put the riverfront and the whole surrounding area underwater, guess again. There is no way that public policy makers are going to let that happen. In 50 or 100 years, they will be building a dike across the base of the Meadowlands, and water will be pumped over as needed, just like in Holland.
Environmentalists might not like seeing the end of the daily tides in the Meadowlands and a transition to a freshwater ecology, but that's just too bad. Billions of dollars of real estate in North Jersey aren't going to be under the sea, when all that is needed is a good strong dike. In fact, there are already dikes in the Meadowlands. Take a look at the dike on Berry's Creek at high tide. It's downright scary, but it works. It's behind a warehouse somewhere in Moonachie or Carlstadt.