hungry cow

While at school I bowfish in the French Broad river that borders the edge of campus. I did all last spring and this summer without any problem. But tonight my RA told me that was told by the dean of students that it is illegal for a bow to be possessed on school property because it is a weapon. I don't think they have a problem personally with me bowfishing, it is a small Christian college and they know that there is absolutely no danger to anyone for me to have a bow. Even the president of the college talked to me while I was bowfishing once and thought it was a neat thing to do. Teachers have given me tips on where to look for the carp. I don't shoot around people, but from the woods or wading. So they must just want to cover themselves to make sure they are not liable for anything. Is this an actual state or federal law I am breaking? Would it be an diffrent if I park by the river and wade without actuall being on campus property? If this isn't really a law or they are misunderstanding it I would like to know because they and I know that I am not causing any problems for anyone.