This legislation, known as the "Northern Montana Water Security Act of 2025," primarily seeks to achieve a fair, equitable, and final settlement of water rights claims for the Fort Belknap Indian Community of Montana. It authorizes, ratifies, and confirms a water rights compact between the Community and the State of Montana, directing the Secretary of the Interior to execute it and take necessary actions for implementation. The bill confirms the Fort Belknap Indian Community's Tribal water rights , to be held in trust by the United States and not subject to loss through non-use. It grants the Community authority to allocate, distribute, and lease these water rights, both on and off the Reservation, subject to Secretarial approval or approved tribal leasing regulations. A key provision requires the Community to enact a Tribal water code for managing these rights, including provisions for allottees' water use and a dispute resolution process. Significant land provisions are included, authorizing the exchange of federal and state lands, with the acquired state lands to be taken into trust for the Community. Specific federal lands are also designated for direct transfer into trust for the Community, expanding the Reservation. Additionally, approximately 2,500 acres of Bureau of Reclamation land, known as Dodson Land , will be taken into trust, subject to a perpetual easement for Milk River Project operations. All newly acquired trust lands are prohibited from being used for gaming. The settlement includes an allocation of 20,000 acre-feet per year of water from Lake Elwell to the Fort Belknap Indian Community for any beneficial purpose. The bill also mandates federal investment in water infrastructure, including the restoration of the St. Mary Canal and enlargement of the Dodson South Canal for Milk River Project mitigation . Furthermore, it directs the rehabilitation, modernization, and expansion of the Fort Belknap Indian Irrigation Project System . To fund these initiatives, the bill establishes the Aaniiih Nakoda Settlement Trust Fund for the Community, with accounts for irrigation development, water resources administration, and clean water/sewer systems. It also creates the Fort Belknap Indian Community Water Settlement Implementation Fund for federal project costs. The legislation authorizes substantial appropriations, including mandatory funding and a state cost share, with provisions for cost adjustments due to inflation. In consideration of these benefits, the Fort Belknap Indian Community and the United States (as trustee) will waive and release certain water rights claims and claims against the U.S. for past damages. However, specific claims are reserved, such as those related to the enforcement of recognized water rights, water quality, and off-reservation hunting/fishing rights. The settlement's effectiveness hinges on an "enforceability date," requiring tribal approval, court approval, and full appropriation of funds. Separately, the bill authorizes $250,000,000 for the planning, design, construction, operation, maintenance, and replacement of community water distribution and wastewater treatment facilities for the Blackfeet Tribe of the Blackfeet Indian Reservation of Montana.