4.—(1) Without prejudice to paragraph 3, the Corporation shall not dredge the river within the harbour limits without the consent of the Belfast Harbour Commissioners.
(2) Any materials taken up or collected in the course of dredging the river shall be the property of the Corporation and may be used, sold, removed, deposited or otherwise disposed of as the Corporation may think fit; but the Corporation shall not deposit any such materials below the level of mean high water springs except in such position as the Secretary of State concerned with navigation may approve and subject to such conditions and restrictions as he may impose.