lead agencies with respect to any activity to plan, design, and construct the water diversion, delivery, and conservation features of any Navajo water development project to be constructed by that agency. (c) Scope The agreement and this Act contemplate a comprehensive approach to addressing identified Reservation water needs by providing funds for domestic and municipal water supply and distribution infrastructure and agricultural water conservation. To allow the Navajo Nation flexibility in meeting the needs of its people over time as both circumstances and technologies evolve, the costs to meet Reservation water needs determined in the studies identified in the agreement were used to establish the dollar amount of the Navajo Water Development Fund. To help ensure that water supply and distribution systems constructed pursuant to the agreement and this Act can be successfully developed and transitioned to be user-supported systems, the agreement and this Act also provide for a Navajo OM&R Trust Account. (d) Final water supply system projects (1) Design review Prior to beginning construction activities for any water supply system as described in the agreement and constructed pursuant to this section, the Secretary shall review the design of the proposed Navajo water development projects and perform value-engineering analyses. (2) Negotiation and agreement with the Navajo Nation On the basis of the review described in paragraph (1), the Secretary shall negotiate and reach agreement with the Navajo Nation regarding appropriate changes to the final design so that the final design meets applicable industry standards, as well as changes, if any, that would allow the projects to be constructed for the amounts made available under subsection (a) of section 7, and improve the cost-effectiveness of the projects. (e) Nonreimbursability of costs All costs incurred by the Secretary in carrying out this section shall be nonreimbursable. (f) Funding (1) Federal obligation The total amount of obligations incurred by the