Local Drug Dealer

I have knowledge of a high school student who supplies a significant amount of the high school kids with drugs. Marijuana, mainly, but I believe there may be more. A friend of mine found out where he gets his supply from by accident, and the person who let the information slip quickly went back and informed the high school dealer. I want to finally shut this guy down, but I don't want something drastic to happen to my friend. And knowing this dealer, something drastic may very well happen. Also, I am aware of the idea of a power vacuum; I take this guy down and another steps in to fill the shoes of whomever I am able to turn in. Any advice on how to proceed from here?

Many high schools have a police officer on campus. Talk to your school security with this officer and the principal present. If you're uncomfortable with that, then talk with your school counselor first. Do not try to handle this on your own.

It sounds like you're worried about information leaking about your friend's discovery. Counselors have a strict policy against divulging personal information, unless it relates to a confession about someone preparing to commit a crime, without that person's consent; in that case, they can only tell the police. Security personnel don't technically have to follow that rule, but they may choose to; naturally, police can't talk about an open case, without permission.

I think you would need to proof he's a drug dealer and u
Would need evidence to lock him up he could be working for someone or he could be alone he probably has friends

if he is dealing to kids i say get proof and report him to the proper authorities, but don't do it for the sol fact of it having something to do with pot. I for one am a medical Marijuana patient and would hate to see some innocent guy go to jail

Don't try to gather evidence on your own in this case. An inexperienced investigation can tip off the suspect, no matter how slick one might perceive themselves. Tell school officials about your suspicions and the reason for them. Let them handle the legalities.