Blackfeet Water Rights Settlement Act of 2013

Directs the Secretary to conduct a study to:

evaluate alternatives for the rehabilitation of the St. Mary Storage Unit of the Milk River Project,

identify alternatives to provide additional St. Mary River and Milk River water to the Tribe,

evaluate the feasibility of increased storage in Fresno Reservoir,

allocate costs based on specified Milk River Project purposes, and

plan the management and development of water supplies in the St. Mary River and Milk River basins.

Requires the Secretary to implement the Swift Current Creek Bank Stabilization Project and offer to enter into an agreement with the Tribe to establish a process for resolving issues regarding federal Milk River Project property interests that are located on tribal lands.

Gives the Tribe the exclusive right to develop and market hydroelectric power from the St. Mary Storage Unit of the Milk River Project.

Directs the Secretary to allocate to the Tribe 56,000 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 Secretary, acting through the Commissioner of Reclamation, to:

carry out deferred maintenance and Four Horns Dam safety improvements relating to the Blackfeet Irrigation Project;

carry out the Birch Creek Mitigation Project to provide water from Four Horns Reservoir to state water rights users on Birch Creek;

plan, design, and construct the MR&I System (involving water intake, treatment, pumping, storage, and pipeline facilities); and

construct the Blackfeet Water, Storage, and Development Projects.

Establishes the Birch Creek Mitigation Fund to mitigate the impacts of development of the Birch Creek tribal water right on the Birch Creek water supplies of the Pondera County Canal and Reservoir Company Project.

Directs the Secretary, at the Tribe's request, to convey title to the Blackfeet Irrigation Project, Birch Creek Mitigation Project, the MR&I System, and Blackfeet Water, Storage, and Development Projects to the Tribe.

Authorizes, ratifies, and confirms the Blackfeet-Montana water rights compact (Compact) to the extent it does not conflict with this Act.

Requires the tribal water rights to be held in trust by the United States for the Tribe and its allottees.

Requires the Tribe to amend its tribal water code in accordance with the Compact and this Act. Requires the Secretary's approval of the tribal water code for it to be valid.

Establishes the Blackfeet Settlement Trust Fund. Makes appropriations to specified accounts that the Secretary is to establish within the Fund. Authorizes the Tribe to withdraw amounts from the Fund upon the Secretary's approval of a tribal management plan and an expenditure plan that requires the Tribe to spend the withdrawn amounts in accordance with this Act.

Gives the Tribe specified water rights in the Lewis and Clark National Forest.

Provides for the waiver and release by the Tribe of water rights claims against Montana and the United States in return for recognition of the tribal water rights and other benefits provided under the Compact and this Act.

Absolves the United States from liability for any failure to carry out any obligation or activity authorized by this Act if adequate appropriations are not provided expressly by Congress to carry out the purposes of this Act in the Reclamation Water Settlements Fund or the Emergency Fund for Indian Safety and Health.