Hi Saen,
You won't find any naturally occurring cod in the hunter valley, glenbawn dam has a few which were illegally stocked years ago,I don't think it would be worth targeting them as their numbers are very small although some large cod have been caught in there over the years by anglers fishing for bass and yellas.I recently read a post on fishnet where a bloke reckons there's cod in glennies creek dam could be true but I've never heard of any being caught in there.Depending on which part of the hunter your in the closest dams where cod are stocked would have to be chaffey,keepit and splitrock to the west,windamere to the southwest.
Tim