Not too many. I only saw one in the enclosure yesterday, I saw a couple at Monarto a few years ago, and a few at Werribee late last year. They don't seem to be a species many people talk about.
to revive an old photo, who would be able to estimate the numbers of waterbuck in Australia now? Werribee say on their website they have a group of 5, - 1:2:2 young males, any idea how many others are in the country? They must still be breeding but getting rather inbred. A few years back, Werribee had a group of 6 females where the gorillas are now, and 3 males (incl 1 with very deformed, almost no horns) out in the savannah.
We just came back from Dubbo and there were no Waterbuck there at all. The closest we got to them was my boys' Waterbuck toy he bought at the gift shop.