Don't think it is decurrens. I need close up of leaves to id wattles, and flowers especially if just coming out from buds, or pods it they are there. Maybe some other moderator can help...
I can see the glands on the rib between the pinnules in the leaf in side view. Difficult to tell apart from A. mearnsii. Look at the first pic at Acacia mearnsii showing the dark colour of the branchlets for A. mearnsii. A. parramattensis does not have that colour, I think.