This subchapter shall not be construed to repeal or amend any local and special act passed before February 16, 1939, pertaining to the operation, control, or management of any light or water plant or sewer system in this state or to the creation or election of any board of directors or like board for the management, control, and operation of any light or water plant or sewer system being controlled or operated under the terms of such local or special act.