84. Local authorities to observe their own policy statements and
 plans---(1) While a policy statement or a plan is operative, the
 regional council or territorial authority concerned, and every consent
 authority, shall observe and, to the extent of its authority, enforce
 the observance of the policy statement or plan.

   (2) No purported grant of a resource consent, and no waiver or
 sufferance or departure from a policy statement or plan, whether written
 or otherwise, shall, unless authorised by this Act, have effect in so
 far as it is contrary to subsection (1).