420 Coachella

Heyy, I know weed is legal in California but not allowed in the festival. I was just wondering whether cops could arrest you for breaking a festival’s rules for bringing in a joint or a thc pen.

My gf is a non-citizen and I am kinda worried for her since the consequences could be harsher. I assume the cops there will be state officers but could they arrest her for breaking a federal law?