(2) In any suit, action, or proceeding involving the validity or enforcement of, or relating to, any contract, proceeding, or action of the district, the district shall be deemed to have been established in accordance with the provisions of this article upon proof of the adoption of the resolution of the county board declaring the county to be a soil and water conservation district. A copy of such resolution duly certified by the clerk of the board shall be admissible in evidence in any such suit, action or proceeding and shall be proof of the filing and contents thereof.
(3) Any soil conservation district heretofore created or existing shall be deemed to be continued for all purposes and shall hereafter be designated as a soil and water conservation district.
(4) Notwithstanding any other provision of this chapter, the mayor of the city of New York shall have the authority to establish a soil and water conservation district encompassing the five counties of the city.