You should consult with the town engineer to determine the scope of the flooding concern.
You could also ask about drainage alternatives that may mitigate the issue.
Tom Hinz http://www.shortsaletosell.com
So, if it is already subdivided from raw land to building lot, it should be fine and buildable. And, as I can guess, this building lot is BIGGER than all other building lots of the same builder because you need sufficient building envelope to put a house to be built. That is to say, you get what other building lot has PLUS the wetland adjacent to your lot and of course a free small stream.
You can NOT build on the webland area of your building lot, but if you carefully look at the NJDEP maps, you see the 100 year flood line and 30 year flood line. That is to say, beyond that line no flood for past 100 years or 30 years. e.g. do not think of building a tennis court at your backyard that fall in the webland.
Also, the land should be high in front and low in the rear, according to what you describe, and it is a nice lot to build a house with "walk out basement" where wealthy people love in their million dollar house, and your main floor would be 2nd floor and 3rd floor. From front, you shall have a steps up to your main door. The house shall look very luxurous and huge. Space wise, you got full basement, but you can walk out in the rear with glass door.
If there is big area of your lot that is in wetland, you can also deduct tax for Conservation Easement, meaning you "give out some right" to governemnt to preserve the environment, in turn, you deduct the loss from your income tax. That's why many wealthy colleagues and friends I know bought land with huge conservation easement and use them as tax sheltor ...
The agent representing you should be able to answer these questions. But given you seem to have asked them, here are some concerns:
You need to get the flood zone status of the property. If the property sits in a flood plain, it may require you to get flood insurance - least of your worries. If it sits in a flood plain, do you really want the headache of having to potentially deal with a flood?
As you also suspected, you could be dealing with wetlands restrictions. You need to get a copy of all title disclosures, including the survey, deed restrictions, etc. This can get complicated, so seriously consider getting an expert to deal with all the questions, which your agent should have access to.
My wife and I were looking at houses a couple of years ago. We found one we really loved, but decided against it because it had a stream in the backyard. We were worried that the stream could prevent a danger for our very young daughter. Admittedly the risk was very low, but we just didn't want to take the chance. If there are more buyers out there that think like we did, this could hurt the re-sale value of the house.
Cynthia (Cindy) Nina-Soto
Contact the municipality where this property is located. They can advise you whether the property is in flood plain (which could increase your home owners insurance cost) It may be considered wet land or conservancy, which depending on your local restrictions could determine what may or may not be done with the land. Depending on the size of the property this could be an asset or a negative - if you like the privacy and water frontage...
Just make sure you are satisfied with the answers you receive on the land use prior to making your decision. Hopefully your agent may be able to access some pertinent data for you also.