This bill grants "limited immunity from criminal prosecution for any person under the age of 21 years who is subject to prosecution ... where the person under the age of 21 years called 911 and reported that either himself or herself or another person was in need of medical assistance due to alcohol consumption and conformed to other specified requirements."
You are protected from consequences under these circumstances.
Always call if you are concerned. You could save someone's life.
A similar protocol exists on campus. See Aggies Act.