Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 91, § 64

(a) The department of conservation and recreation shall create a state uniform beach warning and safety flag program to be used at all public coastal beaches maintained and guarded by the department. The program shall provide for a uniform size, shape, color and definition for each warning and safety flag deemed necessary by the department. The program shall warn the public of drowning and injury hazards presented by changes in tide and surf conditions.

(b) If the department defines any safety flags as warnings of health hazards presented by the quality of the beach water, such definitions shall be based on water quality testing procedures that ensure the warnings are timely, frequently updated and reflect, to the maximum extent feasible, the actual water conditions at the time the flags are posted and for the duration of their posting.

(c) A city or town having jurisdiction over a public beach along the coast may utilize at such beach the state uniform beach warning and safety flag program created by the department of conservation and recreation. Subsection (a) shall take effect in a city with a Plan D or Plan E charter by a vote of the city council upon submission by the city manager and in all other cities by a vote of the city council with the approval of the mayor and in a town with a town council, by vote of the town council and in all other towns, by a vote of the town meeting.