Expenditures of funds hereafter specifically appropriated for rehabilitation and betterment of any project constructed under authority of the Small Reclamation Projects Act (Act of August 6, 1956, 70 Stat. 1044, and Acts amendatory thereof and supplementary thereto) [43 U.S.C. 422a et seq.] and of irrigation systems on projects governed by the Federal reclamation laws (Act of June 17, 1902, 32 Stat. 388, and Acts amendatory thereof or supplementary thereto), shall be made only after the organizations concerned shall have obligated themselves for the return thereof, in installments fixed in accordance with their ability to pay, as determined by the Secretary of the Interior in the light of their outstanding repayment obligations, and which shall, to the fullest practicable extent, be scheduled for return with their construction charge installments or otherwise scheduled as he shall determine: Provided, That repayment of such loans made for small reclamation projects shall include interest in accordance with the provisions of said Small Reclamation Projects Act. No such determination of the Secretary of the Interior shall become effective until the expiration of sixty days after it has been submitted to the Committee on Energy and Natural Resources of the Senate and the Committee on Natural Resources of the House of Representatives; except that, any such determination may become effective prior to the expiration of such sixty days in any case in which each such committee approves an earlier date and notifies the Secretary in writing, of such approval: Provided, That when Congress is not in session the Secretary’s determination, if accompanied by a finding by the Secretary that substantial hardship to the water users concerned or substantial further injury to the project works will result, shall become effective when the chairman and ranking minority member of each such committee shall file with the Secretary their written approval of said findings. The term “rehabilitation and betterment”, as used in this section, shall mean maintenance, including replacements, which cannot be financed currently, as otherwise contemplated by the Federal reclamation laws in the case of operation and maintenance costs, but shall not include construction, the costs of which are returnable, in whole or in part, through “construction charges” as that term is defined in section 485a(d) of this title. Such rehabilitation and betterment work may be performed by contract, by force-account, or, notwithstanding any other law and subject to such reasonable terms and conditions as the Secretary of the Interior shall deem appropriate for the protection of the United States, by contract entered into with the organization concerned whereby such organization shall perform such work.