Section 12C. Said commission shall construct, equip and maintain at beaches under its control public bathhouses with dressing rooms, lockers and toilet facilities, as well as parking facilities, and other recreational facilities, may make reasonable rules and regulations for the care, maintenance, protection, policing and equal public use of said beaches, bathhouses, parking areas, and other recreational facilities, and may make reasonable charges for all facilities installed. At least one attested copy of such rules and regulations shall be posted at such beaches and any violation thereof shall be punished by a fine of not more than twenty dollars for each offence.