It would be useless to have such a tower up unless it has the additional hardware, software, and other infrastructure to listen to anyone. Then the laws of the land also keep any other party other than the US Gov't permits to use that system. Finally, having a system up such as this, it is no way means that it is being used to listen to private citizens conversations. Unless it is proved otherwise, it is of no consequence.
In fact, if anyone wanted to listen to others' conversations, they would not need to go to those same lengths to that end.