These boundaries are set out as provided in the Coastal Marine Area and River Mouths Boundary Agreement 1 August 2008 which refers to Coastal Marine Area boundaries as set out in the Resource Management Act 1991: "The landward boundary of the coastal marine area shall be the lesser of: (i) One kilometre upstream from the mouth of the river; or (ii) The point upstream that is calculated by multiplying the width of the river mouth by 5.
This data is operative as at December 2019.