Is it legal to drive a golf cart on a private course while intoxicated?

I golf frequently at a private golf course near my house. They serve alcohol on the course (a snack cart drives around) and I sometimes see people bring their own flasks of liquor to the course. I often see people who are drunk driving the golf carts. Is it legal because it is on private property or could you get a DUI for that?

I live in Colorado.