Natural feature boundaries are, at common law, ambulatory in nature, and are subject to the doctrine of accretion and erosion. The doctrine applies to boundaries of both tidal and non-tidal waters including rivers, streams, the sea and inlets to the sea. It also applies to other natural feature boundaries such as cliff faces and ridgelines. The doctrine allows for the movement of a boundary where the change in the position of the bank, shoreline or other natural feature has been natural, gradual and imperceptible.
In respect of lands alienated on or after:
- 3 May 1918 in the Eastern and Central Divisions and
- 31 May 1935 in the Western Division,
section 13.3 of the Crown Land Management Act 2016, affirms that the title to the beds of all rivers, adjoining lands alienated on or after that date, is vested in the Crown. As a consequence, any variation shown in a plan from the line of the river bank as at the date of alienation will require the approval of Crown Lands. See Consent to natural boundaries.
NOTE: The change in the position of the bank must only be discernible over a significant period of time not as a result of a sudden storm or flood.
NOTE: In cases where accretion or erosion has occurred suddenly (i.e. the process did not occur in a natural, gradual and imperceptible manner) the former definition of the bank will not change. In these cases the natural feature boundary may extend into the water and the parcel will include part of the actual stream-bed or waterway. See Tidal Boundaries.
The doctrine of accretion and erosion does not apply to non-tidal lakes or lagoons.
Accretion
This occurs where water recedes from the land, or where land builds up by alluvial deposits as added by horizontal progression outwards from the bank or shoreline.
Accretion does not apply where there has been a vertical development over a wide area rather than a gradual extension of existing land.
For example, where a fast flowing river deposits sand and silt in a fan shaped pattern at the entrance to a lake, so as to cause the lake bottom to appear above the water level and eventually join to the land, accretion does not apply. See Re Bulman (1966)57 D.L.R. (2d) 658 British Columbia Supreme Court]. This is so even where the land becomes arable by the gradual advance of top soil across the raised lake bottom from the existing land.
Further, where accretion is claimed, the opposite bank of the stream must also be plotted as defined in the existing current plan. In the absence of a definition in that plan, it will be plotted in accordance with its relationship to the near bank as shown in prior plans or maps
NOTE: The doctrine of accretion and erosion as it applies to the definition of the MHWM of the coastline or a tidal river is modified by section 28 Coastal Management Act 2016, see Tidal boundaries (MHWM).
NOTE: The general principle of accretion applies even though the gradual and imperceptible build-up has been unintentionally assisted, or would not have taken place without, the erection of groynes, etc. for the purpose of protecting the shoreline from erosion.
Erosion
This is the natural and gradual retreat of the bank or shoreline into the adjoining land caused by the action of a river, stream or the sea.
Accretion/erosion report
Where accretion or erosion is disclosed, the surveyor must furnish a comprehensive report indicating whether the change in position of the river is due to:
- a gradual and imperceptible movement by natural means
- a sudden shift, as would happen in flood time
- differences caused by adopting either high or low banks or
- errors in the basic survey information, which may mean that the river has not changed its course at all.
In addition, the surveyor must furnish any other evidence available to support the definition, for example, statutory declarations by local residents with the necessary knowledge of how the change took place.
Once lodged at NSW LRS, the evidence requested will be considered, together with any related aerial photographs of the area, and a decision will be made as to whether the definition in the plan is acceptable.
All NSW legislation can be accessed at www.legislation.nsw.gov.au/
Publish date: December 2023