Territorial authority districts of New Zealand

The "lowest" level of local government that affects the whole of New Zealand is the city and district level. Every part of the North Island, the South Island, and the more substantial of the nearby smaller islands is part of either a city or a district. The Chatham Islands are a "territory" with a council that has district and regional powers, making it similar in function to a unitary authority.

Schedule 2 of the Local Government Act 2002 says this:

2. Boundaries of districts— (1) If any part of the boundary of a district is the sea, that boundary may be between the mean high-water mark and the outer limit of the territorial sea of New Zealand as determined by the Order in Council defining the district. (2) If a river or stream runs between 2 or more districts, wholly or in part, the boundaries of the relevant districts, for the purposes of this Act, extend to the middle line of the river or stream and follow its natural course. (3) If the boundaries of a district are altered and all or part of the boundaries concerned were the same as the boundaries of any region,—
 * (a) the alteration also has effect with respect to the boundaries of that part of the region; and
 * (b) the boundaries of the region are altered accordingly.

(4) Subclause (3) applies subject to the Order in Council giving effect to a reorganisation scheme.