As a previous college student, I am glad that I never prevented myself from drinking because I was concerned about my body fat % increasing slightly or losing a little bit of muscle. I lifted hard, usually ate right, and when it came time to party, I partied hard. As long as your not out getting slammed every night or every other night, don't deny yourself the full college experience.
When you look back, what will you remember first, the great nights you had, or your blown chance to stay at 10% body fat instead of 11 or 12? Or the fact that you could have benched 10 lb more your junior year had you not drank and had fun. You have the rest of your life to drink moderately and concentrate on your physique and lifts to fullest extent .