Where any bona fide desert-land entry has been or may be embraced within the exterior limits of any land withdrawal or irrigation project under the Act of June 17, 1902, and the desert-land entryman has been or may be directly or indirectly hindered, delayed, or prevented from making improvements or from reclaiming the land embraced in any such entry by reason of such land withdrawal or irrigation project, the time during which the desert-land entryman has been or may be so hindered, delayed, or prevented from complying with the desert-land law shall not be computed in determining the time within which such entryman has been or may be required to make improvements or reclaim the land embraced within any such desert-land entry: Provided, That if after investigation the irrigation project has been or may be abandoned by the Government, time for compliance with the desert-land law by any such entryman shall begin to run from the date of notice of such abandonment of the project and the restoration to the public domain of the lands withdrawn in connection therewith, and credit shall be allowed for all expenditures and improvements theretofore made on any such desert-land entry of which proof has been or may be filed; but if the reclamation project is carried to completion so as to make available a water supply for the land embraced in any such desert-land entry the entryman shall thereupon comply with all the provisions of the aforesaid action ¹ of June 17, 1902, and shall relinquish within a reasonable time after notice as the Secretary may prescribe and not less than two years all land embraced within his desert-land entry in excess of one farm unit, as determined by the Secretary of the Interior, and as to such retained farm unit he shall be entitled to make final proof and obtain patent upon compliance with the regulations of said Secretary applicable to the remainder of the irrigable land of the project and with the terms of payment prescribed in said Act of June 17, 1902, and not otherwise. But nothing herein contained shall be held to require a desert-land entryman who owns a water right and reclaims the land embraced in his entry to accept the conditions of said reclamation Act.