Federal maritime laws, state and federal wildife agencies, EPA, state property laws, county and municipal ordinances. And no one wants to be responsible for the salvage costs which can be high with environmental damage and potential fuel spills; especially since the owners of the derelicts, if they can be found, probably have little money themselves. Even those that live aboard are probably barely eaking by - like many of us on land.
I've known many of the people that live on these boats. Most are fiercely independent in the true Amaerican tradition. They're not looking for handouts and just want to be left alone. But they have no resources to fall back on and would have no choice but to abandon their boats if events turned against them. For the ones trying to regulate the anchorages, their boats and lifestyle are eyesores. For the ones aboard, it is their life and they're doing what they can.