My daughter is a college freshman. My policy to her was that she's years away from being of legal drinking age, and so I do not want her anywhere where alcohol is served. And that if I find out she's been to one she's on curfew from that point on
If she's at home, that'll work fine. But I don't know how you would know if she's away at school until it's too late. Frankly, the best way (it's the way that my parents used with me) is to teach kids how to drink responsibly and how to protect themselves at college. IMO, the girls who get themselves into trouble in college are the naive, good girls, whose parents just tell them don't drink because I said so and don't provide any sort of guidance or leeway.