A dispute over where a boundary is located can usually be solved by having a survey completed by a surveyor, who will mark the boundary (according to the land title documents) on the ground or on existing structures. A person who deliberately moves or removes a survey peg (other than to build on the boundary or as permitted under the Survey Act 1992 (SA)) commits an offence. That person can be fined up to $2000 and will be liable to pay for the boundary to be re-surveyed [s 52].
If a river or stream runs between two properties, the centre of the stream is usually the boundary, although this kind of boundary can change as the stream gradually cuts a new course.
Generally, if a fence is not on the proper boundary, it does not change the ownership rights to the land.