The Water Resources Commission shall make all necessary arrangements to secure the settlement, cultivation and reclamation of Carey Act lands in the Tumalo Project; accept applications for the entry of the lands; make contracts for the purchase of water rights and release of lien for the lands; make rules for their cultivation and settlement; and prescribe the forms to be used for such purposes. Each contract with purchasers shall provide for payment of the full amount of lien assessed against the tract covered by the contract within a period of not to exceed 20 years, with interest on deferred payments at five percent per annum, and shall also provide for payment of an annual maintenance fee, to be fixed by the commission. Contracts executed before May 27, 1913, may be brought under the terms of ORS § 555.310 to 555.410, and the rate of interest thereunder shall be five percent from and after December 1, 1916. Contracts for the sale of water rights to private lands within the project shall be upon the same terms and conditions as for Carey Act lands, and the commission shall in addition require the purchaser to give a first mortgage on such private lands, to the state, as security for the payments due under the contract. The contracts with purchasers, both on Carey Act and private lands, shall provide for the sale of a proportionate interest in the reclamation system to each purchaser, and for transfer of the reclamation system to the purchasers when the water rights for a majority of the lands in the project have been fully paid for, the state retaining an interest proportionate to the unpaid balance on the contracts.