After recent discussions on the COG Chatline I've realised that the Lake Ginninderra mallards have never been reported on Canberra Nature Map. I had avoided reporting what I thought were obvious known sightings.
And given the continued discussion on the COG Chatline, and many earlier discussions to which GD has drawn our attention, it probably best not to call the birds in your photos Lake Ginninderra ‘mallards’, but rather Lake Ginninderra domestic ducks with indications of mallard in their parentage.
This matches the ebird notation where all domestic ducks are denoted Domestic Mallard. There is a separate entry for Wild-type mallards which do not have a Domestic notation.