It is the purpose of this chapter to provide for the regulation of nonconforming buildings, structures, and uses and to specify those requirements, circumstances, and conditions under which nonconforming buildings, structures, and uses will be operated and maintained. The zoning ordinance establishes separate districts, each of which is an appropriate area for the location of uses which are permitted in that district. It is necessary and consistent with the establishment of these districts that nonconforming buildings, structures, and uses not be permitted to continue without restriction. Furthermore, it is the intent of this chapter that all nonconforming uses shall be eventually brought into conformity.