I am not sure if you are surprised by the fact that this happens at a highly selective D3 school or if it is surprising that it happens at all. Only insight I can share, having two in college (based on the info shared with me) is that sometimes the level of drug and alcohol use is higher at the more expensive schools, where much of the student population has a greater disposable income. Selectivity of the school academically does not seem to matter.
If you have a concern about the prevalence of drug and alcohol overall you may want to consider a religious based institution that has stiffer policies and penalties for drug and alcohol use. But as for alcohol, since most students turn 21 during their time in college, a student will have to learn how to make their own choices, balance parties, school and sports as part of the overall experience.
The NCAA does allow testing for drugs but it is typically a school’s athletic department that monitors and has penalties for underage drinking and tobacco use. Consuming alcohol if the student is above the age of 21 is not an NCAA violation that I am aware of. Although I would suspect if a student athlete was hung over every weekend performance issues would be the bigger problem.