as others have said
it is red on right when returning
your green river bouy may be a bit more challanging if the river is
open at both ends or if it is so long that you don't know which way is
returning. keep in mind that the bouy numbers go up when returning. One
of the best things to do is to get charts and see what the red and
green bouys are keeping you away from. then you begin to understand
what they mean
hope this helps