This question reminds me of my Dad years ago, in another part of the country, when I was about to enter the local magnet school in avpart of town that wasn't great. My Dad asked my cousin (who was already a student) if there were a lot of drugs around. My cousin replied that while he was sure some kids used drugs, he'd never been approached or seen others using. He guessed they could tell he wouldn't be interested. His answer assuaged my Dad's concerns enough to let me go. The worst thing I saw was some kids smoking in the campus parking lot, and they weren't trying to involve me. Granted, smoking is awful, but I don't think it's what OP is concerned about, and in the 80s the smoking culture was more prevalent.
In college, likewise, I saw plenty of drinking and smoking, but no drugs.
My kids went to Blair, and to the best of my knowledge, their experience mirrored my own. They're not interested in drugs and neither are their friends.
I suspect in any school, a kid who wants drugs can find them. Similarly, as long as the drug culture hasn't taken over the school, I imagine a kid who has no interest in drugs and is involved in other things will gravitate toward like-minded peers and probably will have little, if any, contact with drugs.
For those who want statistics by school, you can select a specific school on the MCPS website, scroll down to Reports, and then select School Safety and Security at a Glance.
https://www.montgomeryschoolsmd.org/schools/