In deciding the nominal volume for a water allocation in a water allocation group mentioned in schedule 6 , table 1, column 1, the chief executive—
(a) must have regard to—(i) the local availability of water; and(ii) the conditions under which the water may be taken under the authorisation; and(iii) the annual volumes of water estimated by the chief executive to have been taken under the authorisation during the period, of not more than 10 years, immediately before the commencement of this plan; and(iv) the simulated mean annual diversion; and(v) the efficiency of the use of the water mentioned in subparagraph (iii); and
(b) must ensure the total of the nominal volumes for the water allocation group is not more than the volume stated in schedule 6 , table 1, column 2, for the group.