Brunswick River floodplain

The Brunswick River is situated to the west of Brunswick Heads.

Most of the population of the valley is concentrated on the extensive floodplain in the lower reaches where the towns of Mullumbimby and Brunswick Heads are situated. Much of Mullumbimby is flood prone, while the future development of Brunswick Heads is severely restricted by the lack of flood-free land.


Catchment of 22,000 hectares, which rises from sea level at Brunswick Heads. to a maximum elevation of 690m.


  • The physical characteristics of the catchment vary from steep, heavily vegetated slopes to open grassed floodplain and flat swamp land behind the coastal dunes.
  • There is no clear demarcation of the catchment boundary in the area of the coastal swamps.

The catchment is drained by three major streams:

  • Marshalls Creek (North Arm)
  • Brunswick River (West)
  • Simpsons Creek (South Arm).

Major floods

Four major floods have affected the catchment. These floods occurred in:

  • March 1974
  • February 1976
  • March 1978
  • June 2005
  • March 2017

Flood Studies

North Byron Floodplain Risk Management Study and Plan

The North Byron Floodplain Risk Management Study and Plan was adopted during the Byron Shire Floodplain Risk Management Committee Meeting held on 20 August 2020. 

North Byron Flood Study (adopted February 2016)

This study combines the Marshalls, Simpsons and Brunswick Catchments using current flood modelling practices and the more detailed terrain modelling from a recent aerial laser survey. The study considers the urban areas of Mullumbimby, Billinudgel, Brunswick Heads, Ocean Shores, New Brighton and South Golden Beach.

See the North Byron Flood Study for the flood study document and Flood Mapping for the flood maps.

Brunswick River Flood Study (adopted 1986)

Byron Shire Council adopted the Brunswick River Flood Study in 1986, this document was used to make all floodplain development decisions until the North Byron Flood Study was adopted. A draft Floodplain Management Plan was prepared, but never adopted by Council.