Blackfeet Water Rights Settlement Act of 2015

Blackfeet Water Rights Settlement Act of 2015 Authorizes, ratifies, and confirms the Blackfeet-Montana water rights Compact to the extent it does not conflict with this Act. Requires the Blackfeet Tribe of the Blackfeet Indian Reservation of Montana and the Fort Belknap Indian Community to enter into an agreement for the exercise of the respective water rights on the respective reservations of the Tribe and the Community in the Milk River. Requires the Department of the Interior to contract with the Tribe for the delivery of 5,000 acre-feet per year of the St. Mary River water right through Milk River Project facilities to the Tribe or an entity specified by it. Requires specified appraisal and feasibility studies regarding the management and development of water supplies in the St. Mary River Basin and Milk River Basin. Requires the Bureau of Reclamation to implement the Swift Current Creek Bank Stabilization Project and offer to enter into an agreement with the Tribe to resolve all issues regarding federal Milk River Project property interests located on tribal lands. Gives the Tribe, subject to specified limitations and only if the St. Mary Storage Unit of the Milk River Project is rehabilitated, the exclusive right to develop and market hydroelectric power from the Unit. Directs Interior to allocate to the Tribe 50,000 acre-feet per year of water stored in Lake Elwell for use by the Tribe for any beneficial purpose on or off the Reservation. Authorizes the Tribe to enter into leases or other agreements for the use of that water, provided its use occurs within the Missouri River Basin and the agreement does not permanently alienate the allocation. Requires the Bureau of Reclamation, with respect to the Blackfeet Irrigation Project, to carry out: (1) deferred maintenance; (2) Four Horns Dam safety improvements; and (3) rehabilitation and enhancement of the Four Horns Feeder Canal, Dam, and Reservoir in accordance with the Birch Creek Agreement. Requires the Bureau of Reclamation to construct the water diversion and delivery features of the MR&I System. Requires the Tribe, upon request by Interior, to grant, at no cost to the United States, such easements and rights-of-way over tribal land necessary for the construction of the irrigation activities related to the Blackfeet Irrigation Project and for the design and construction of the MR&I System. Prescribes requirements and funding for the Blackfeet Water, Storage, and Development Project. Requires the tribal water rights to be held in trust by the United States for the Tribe and its allottees. Requires the Tribe to enact a tribal water code, subject to Interior approval, in accordance with the Compact and this Act. Establishes the Blackfeet Settlement Trust Fund. Confirms the instream flow water rights of the Tribe in the Lewis and Clark National Forest and Glacier National Park. Requires the Tribe to waive and release water rights claims against Montana and the United States in return for recognition of the tribal water rights and other benefits set forth in the Compact and this Act. Declares this Act repealed if Interior fails to take certain actions by January 22, 2025.