At the conclusion of the hearing, the board shall by resolution determine whether it is necessary or desirable to exclude the territory. If so, the resolution shall also state:
(a) The reasons why such exclusion is necessary or desirable.
(b) That the exterior boundaries of the improvement district following such exclusion are set forth on a map on file with the secretary, which map shall govern all details as to the extent of the then existing improvement district.
(Added by Stats. 1978, Ch. 404.)