It may contribute money to the Federal or the State government or to any county in which the district is located or to any city within the district, for the purpose of defraying the whole or a portion of the cost and expenses of work and improvement to be performed, either within or without the territorial limits of the district, by the Federal, State, county or city government, in improving rivers, streams, or in doing other work, if such work will improve navigation and commerce, in or to the navigable waters in the district.