No embargo as such on Cardinia Creek, it's just that the fossicking area itself is now under a considerable amount of water. Most of the creeks in the Dandenongs are worth a look but obviously not in National Parks or other similar areas. Also check with land owners before entering private property. Years ago, there were sapphires and zircons in the area located between Tatong and Tolmie, not sure of the current status of that area as it was closed to Stringybark Creek and the Kelly Tree. Sounds like you might do well to join a local lapidary club, there are a number spread through the suburbs, Essendon, Nunawading, Mordiallic, Warrigul and Dandenong are a few that spring to mind. There are others. Most of the clubs have organised field trips regularly, they usually have a leader who knows the area and will show you where to go to find whatever it is you're looking for.