N.Y.C. Admin. Code § 24-305: § 24-305 Pollution of or interference with water supply.

It shall be unlawful, within the city, to bathe in or go into the water of any water supply reservoir or any part of a city aqueduct, or to throw stones, chips or dirt or any other material or substance whatever into any gatehouse, ventilator, fountain or basin. It shall also be unlawful to injure or disfigure any part of the water works system of the city.