N.Y. Gen. Mun. Law § 120-b

§ 120-b. Supervision of sewage system. If the public works herein\nprovided be constructed and operated by the municipalities acting\njointly, the local authorities of the contracting municipalities or\ndistricts having charge of sewage shall jointly supervise the\nconstruction and operation of such sewage system, or they may jointly\nengage or employ a competent sanitary engineer for such purpose. They\nshall jointly elect or appoint all necessary employees at the disposal\nplant and for the care of the trunk line sewer, and severally appoint\nsuch employees as they may be authorized so to do by the respective\ngoverning bodies to work on the system within the bounds of such\nmunicipality.\n