Check if the fence will be built in a Land Subject to Inundation Overlay
Refer to the map from VicPlan-external site to see whether the land on which you plan to build the fence is in Land Subject to Inundation Overlay.
If so, consider the materials out of which the fence will be built. Unless the fence is post and wire, or post and rail, you will need Planning permission.
Am I planning to build a fence in a Land Subject to Inundation Overlay out of materials other than post and wire or post and rail?