(1) This subchapter shall not be construed to repeal or amend any valid local or special act heretofore passed pertaining to the operation, control, or management of any light or water plant or sewer system nor to the creation or election of any board of directors or like board elected or appointed pursuant to any special act or acts, nor to plants or systems organized as improvement districts.
(2) Any acts providing for election of members of any boards or commissions shall remain in full force and effect.
(3) Nothing in this subchapter shall be construed to prohibit the city council of any city subject to the terms of this subchapter from repealing or amending any act which it may have passed pursuant to the authority conferred by this subchapter.