The board of supervisors, and the city councils of the cities in the county, may authorize the members of the service authority to receive for each attendance at meetings of the service authority, and for each day any member is engaged in authorized service authority business other than attendance at meetings of the service authority, the maximum sum of one hundred dollars ($100), but not to exceed five hundred dollars ($500) in any calendar month, and to be allowed their actual and necessary expenses incurred in the discharge of their duties.