Actually I think Garnpung Lake near the Mungo National Park is twice the size of Lake George. There are several man-made lakes in the Snowy Mountains which are larger too.
Also - Lake George is a very shallow lake and rarely has much water in it anyway due to high amounts of evaporation - although it is a bit unusual to see it completely dry like it has been recently.
There have been many periods when Lake George has been full. During the 1960s CSIRO Wildlife Division used the lake to study the many species of waterfowl to be found there. I always understood that this was the largest lake in NSW, but am probably wrong in my thinking! Thank you for the update info.@Simon Hampel