(1) To the extent that the Board has not undertaken an activity or project which would be within its power under the provisions of Article V of this compact, any two or more of the party states (acting by their duly constituted administrative officials) may enter into supplementary agreements for the undertaking and continuance of such an activity or project. Any such agreement shall specify the purpose or purposes; its duration and the procedure for termination thereof or withdrawal therefrom; the method of financing and allocating the costs of the activity or project; and such other matters as may be necessary or appropriate. No such supplementary agreement entered into pursuant to this article shall become effective prior to its submission to and approval by the Board. The Board shall give such approval unless it finds that the supplementary agreement or activity or project contemplated thereby is inconsistent with the provisions of this compact or a program or activity conducted by or participated in by the Board.
(2) Unless all of the party states participate in a supplementary agreement, any cost or costs thereof shall be borne separately by the states party thereto. However, the Board may administer or otherwise assist in the operation of any supplementary agreement.
(3) No party to a supplementary agreement entered into pursuant to this article shall be relieved thereby of any obligation or duty assumed by said party state under or pursuant to this compact, except that timely and proper performance of such obligation or duty by means of the supplementary agreement may be offered as performance pursuant to the compact.
(4) The provisions to this Article shall apply to supplementary agreements and activities thereunder, but shall not be construed to repeal or impair any authority which officers or agencies of party states may have pursuant to other laws to undertake cooperative arrangements or projects.