The Building Department issued a permit and the Board of Health approved my septic system. Isn't that enough? They didn't tell me I had wetlands on my property!

The permits issued by other boards and departments will address concerns covered under different sets of laws and regulations.  If they are aware of the presence of wetlands on your property, other officials will be happy to advise you of that.  However, the town is not responsible to tell you about the presence of wetlands - that is your responsibility. The law requires you to tell us - not vice versa.