Where the death of a husband or wife causes lands in private ownership to become excess lands, as that term is used in section 423e of this title, and those lands had theretofore been eligible to receive water from a project under the Federal reclamation laws (Act of June 17, 1902 (32 Stat. 388), and Acts amendatory thereto) without execution of a recordable contract under section 423e of this title, the Secretary of the Interior is authorized to furnish water to them, without requiring execution of such a contract, so long as they remain in the ownership of the surviving spouse: Provided, That in the event of the remarriage of the surviving spouse, such lands shall be governed by applicable law without regard to the provisions of this section.