I received a citation for peeing behind a trash can. I have about 8 months left on my probation for a DUI, is this citation a violation of my probation?

It is a illegal activiity, so yes it is a violation. So what the probation officer will do is hard to say, personal guess after they get done laughing in private they will warn you and do nothing,

But you need to tell the PO and see what happens.