and Replacement Trust Fund are authorized to be used in accordance with paragraph (2). (6) Availability Any amount authorized to be appropriated to the Navajo Nation Operations, Maintenance, and Replacement Trust Fund under paragraph (3) shall not be available for expenditure or withdrawal until the Nation is responsible for payment of operation, maintenance, and replacement costs as set forth in section 10603(g). (7) Fluctuation in costs (A) In general The amounts authorized to be appropriated under paragraph (3) shall be increased or decreased, as appropriate, by such amounts as may be justified by reason of ordinary fluctuations in costs occurring after October 2022 as indicated by the Bureau of Reclamation Operation and Maintenance Cost Index. (B) Repetition The adjustment process under this subparagraph shall be repeated for each subsequent amount appropriated until the amount authorized, as adjusted, has been appropriated. (C) Period of indexing The period of indexing adjustment under this subparagraph for any increment of funding shall end on the date on which the funds are deposited into the Navajo Nation Operations, Maintenance, and Replacement Trust Fund. (8) Management The Secretary shall manage the Navajo Nation Operations, Maintenance, and Replacement Trust Fund in accordance with subsection (d). (9) Conditions for expenditure and withdrawal All expenditures and withdrawals by the Nation of funds in the Navajo Nation Operations, Maintenance, and Replacement Trust Fund must comply with the requirements of subsection (f). (c) Jicarilla apache nation operations, maintenance, and replacement trust fund (1) Prerequisite to establishment Prior to establishment of the trust fund under paragraph (2), the Secretary shall conduct an Ability to Pay study to determine what operation, maintenance, and replacement costs of that section of the Project serving the Jicarilla Apache Nation are in excess of the ability of the Jicarilla Apache Nation to pay. (2) Establishment Upon completion of the Ability to Pay study