(a) To enlarge area of desert-land entry. Amendment for the purpose of enlarging the area of a desert-land entry will be granted under and in the conditions and circumstances now to be stated.

(1) In any case where it is satisfactorily disclosed that entry was not made to embrace the full area which might lawfully have been included therein because of existing appropriations of all contiguous lands then appearing to be susceptible of irrigation through and by means of entryman's water supply, or of all such lands which seemed to be worthy of the expenditure requisite for that purpose, said lands having since been released from such appropriations.

(2) Where contiguous tracts have been omitted from entry because of entryman's belief, after a reasonably careful investigation, that they could not be reclaimed by means of the water supply available for use in that behalf, it having been subsequently discovered that reclamation thereof can be effectively accomplished by means of a changed plan or method of conserving or distributing such water supply.

(3) Where, at the time of entry, the entryman announced, in his declaration, his purpose to procure the cancellation, through contest or relinquishment, of an entry embracing lands contiguous to those entered by him, and thereafter to seek amendment of his entry in such manner as to embrace all or some portion of the lands so discharged from entry.

(b) Conditions governing amendments in exercise of equitable powers; amendments involving homestead and desert-land entries of adjoining lands. Applications for amendment presented pursuant to § 1821.6-5(a) of this chapter will not be granted, except where at least one legal subdivision of the lands originally entered is retained in the amended entry, and any such application must be submitted within 1 year next after discovery by the entryman of the existence of the conditions relied upon as entitling him to the relief he seeks, or within 1 year succeeding the date on which, by the exercise of reasonable diligence, the existence of such conditions might have been discovered: Provided, nevertheless, That where an applicant for amendment has made both homestead and desert land entries for contiguous lands, amendment may be granted whereby to transfer the desert-land entry, in its entirety, to the land covered by the homestead entry, and the homestead entry, in its entirety, to the land covered by the desert-land entry, or whereby to enlarge the desert-land entry in such manner as that it will include the whole or some portion of the lands embraced in the homestead entry, sufficient equitable reason for such enlargement being exhibited, and the area of the enlarged entry in no case exceeding 320 acres. Applications for such amendments may be made under §§ 1821.6-1 to 1821.6-5 of this chapter and on the prescribed form, in so far as the same are applicable. A supplemental statement should also be furnished, if necessary, to show the facts.

(c) Evidence of water-right to accompany application to amend desert-land entry. Application to amend desert-land entries by the addition of a new and enlarged area or by transferring the entry to lands not originally selected for entry must be accompanied by evidence of applicant's right to the use of water sufficient for the adequate irrigation of said enlarged area or of the lands to which entry is to be transferred. Such evidence must be in the form prescribed by § 2521.2.