any pond or lake nearby lol. not to be sarcastic lol but they are in almost every local body of water you can think of. as for haverhill sorry i dont know the area well so i personally couldnt help you but rest assured they are over populating almost any of your local lakes and ponds lol. go to your fav spot and toss some bread out on the water and wait a few minutes to see if it gets sucked under in a swirl of water lol.also a tell tale sign of feeding carp is to look for little streams of bubbles coming up to the surface, if you dont see a turtle come up in a few seconds then those bubbles are from a grazing carp, especially if there are multiple bubble streams popping up in the same general area. apologies if you already know all that stuff its not my intention to insult your intelligence if you are already an avid carp fisherman i just dont know how much you know ya dig ? tight lines
I'm not to surr about haverhill exactly but I do know if you head up to amesbury dear island where its tidal has submarines swimming around. People mostly fish for stripers there but the brackish water carp seem to be huge.there's also a little park where the pow wow river meets the merrimac that can be a good spot to. Pretty much anywhere on the merrimac will do though
Like Bassinbrooksy said, just about any pond or lake up there will have carp. Submarines, LOL....we always called them missiles. Those must be some big boys! Good luck!