N.Y. County Law § 251

§ 251. County agency. The board of supervisors may appoint or\nestablish an officer, board or body, or may designate an existing\nofficer, board or body, or public authority which possesses the express\npower to act as such an agency, to act as a county water, water quality\ntreatment, sewer, wastewater disposal, drainage, refuse or public inland\nlake protection and rehabilitation agency (hereinafter referred to in\nthis article as the "agency") having the powers hereinafter prescribed\nin sections two hundred fifty-two, two hundred fifty-three and two\nhundred fifty-four, and such other powers and duties as the board of\nsupervisors may determine necessary to carry into effect the provisions\nof this article. Except in the case of a public authority, the agency\nmay also be designated as the administrative head or body of any county\ndistrict which may be established pursuant to the provisions of this\narticle. All matters relating to the membership of such agency,\nincluding, but not limited to, numbers, method of selection, tenure,\nqualifications and compensation, shall be determined by the board of\nsupervisors.\n