You're going to have to show me a link where it says that marijuana use is up amongst minors in Colorado because from what I've been reading, it's remained relatively stable prior to, during and since legalization. As for the spike in ER visits, that is true, but the stats are somewhat overblown. ER visits related to consumption is still very low. Accidental ingestion of pharmaceuticals has been (and still is) a bigger problem.
And God forbid if towns switch from mining coal and raising cattle to farming cannabis for their main source of revenue, because we all know how great the former two is for the environment...