I'd imagine there's quite a lot of local music played on the various "college radio" outlets, especially when viewed in the aggregate. Probably there's also some shows devoted specifically to local music on those stations, but I'd imagine they also tend to come and go from semester to semester as the student roster churns.
I suppose you could go to each college station's website and look at their "schedule" page and make some intelligent guesses just based on the individual shows' names as to whether or not they're devoted to local music. Admittedly, this is a somewhat time-consuming and prone-to-error method. :-\