N.Y. CNT Law § 299-U

§ 299-u. Joint construction and operation of projects. Where two or\nmore adjoining counties have established agencies and have created\nwatershed districts for the purposes of this act in the watershed common\nto the counties, the agencies and the administrative heads or bodies,\nsubject to the approval of their respective boards of supervisors, may\nenter into agreements for the planning, installation, construction,\noperation, maintenance, assessments of costs and repair of a joint small\nwatershed project. Any agency or agencies within this state, established\nby a county or counties for the purposes of this act with respect to\nsmall watersheds, may, subject to the approval of the board or boards of\nsupervisors of the county or counties, enter into agreements respecting\njoint projects with one or more "local organizations" in other states as\ndefined in section ten hundred two of title sixteen of the United States\ncode. The provisions of all sections of this article concerning the\nplanning, installation, construction, operation, maintenance,\nassessments of costs and repair of, and the approvals required for a\nproject within a single county of this state, shall apply with equal and\nfull force and effect to a joint project, but nothing herein shall be\ndeemed to prevent or restrict the additional applicability thereto of\nany requirements of another state in any matter relating to its interest\nor the interests of its subdivisions therein.\n