N.Y.C. Admin. Code § 12-129: § 12-129 Hours of service during July and August.

Four hours on any Saturday during the months of July and August, shall constitute a full day's work for all employees of any city agency. The head of any agency shall have power to employ his or her subordinates on any legal holiday, or may employ them on any such Saturday in excess of the legal day's work above prescribed, paying them compensation therefor at the rate of their usual wages or salaries. The provisions of this section shall apply to and include per diem employees, but shall not apply to the uniformed forces of the police and fire departments.