The Navajo-Gallup Water Supply Project Amendments Act of 2025 aims to improve and update the existing Northwestern New Mexico Rural Water Projects Act. It makes substantial changes to the authorization, funding, and operational aspects of the Navajo-Gallup Water Supply Project. The bill also redefines key terms and clarifies various provisions related to the project's implementation. The legislation expands the Project Service Area to include additional Navajo Nation communities in New Mexico and Arizona, anticipating increased service and reduced operational costs. It authorizes the acquisition and construction of facilities, including those associated with the San Juan Generating Station, and mandates the Secretary to take specific land parcels into trust for the Navajo Nation. These lands will become part of the Navajo Reservation, subject to existing rights and easements. A major provision is the increase in authorized appropriations for the Project from $870 million to $2.175 billion , extending the funding period through 2029. The bill also updates mechanisms for adjusting construction costs to account for market volatility and extends the period for certain adjustments. Additionally, authorized appropriations for operations, maintenance, and replacement are increased to $37.5 million through 2032. The Act introduces a Deferred Construction Fund , allowing the Navajo Nation and the Secretary to mutually agree on deferring certain project facilities to save on operational expenses. This fund will hold corresponding amounts for future construction or alternative facilities. The bill also revises the framework for several Settlement Trust Funds , including the Navajo Nation Water Resources Development Trust Fund and two Operations, Maintenance, and Replacement Trust Funds for the Navajo and Jicarilla Apache Nations, outlining their establishment, use, investment, and management. New provisions clarify the taxation of project construction, operation, and maintenance activities, specifying that activities on trust land are subject to Navajo Nation taxation, while those on other lands are subject to state or local taxes. Furthermore, the bill authorizes the Navajo Nation to convey up to 2,000 acre-feet per year of non-Project water to its communities in Utah, subject to specific conditions, including accounting for this water against Utah's apportionment and requiring an implementation agreement with the State of Utah. This non-Project water conveyance must not delay the main Navajo-Gallup Water Supply Project.