Most official "wetlands" are not what you would think are wetlands. They are essentially nothing- but due to newer environmental regs we have to call them wetlands. So, for many cases there are no true concerns like flooding.
However, if the wetlands are more significant and are part of a major river system in Salem or wherever, then potentially there could be true flooding issues.
Did you check the FEMA flood may (online- by address you can check) it the home is in a flood zone.
The bigger part about wetlands is the setbacks these days, which can be up to 100 feet now. No building, including pools etc within that setback limit. Each town has different rules; check with the town's conservation comm. or building dept.
If I can be of any other help, please let me know. Thanks,