To clarify that, with respect to each Missouri River mainstem reservoir of the Corps of Engineers located in a State, the State maintains authority to allocate and appropriate the quantity of water in the reservoir that is attributable to the natural flows of the Missouri River within the boundaries of the State, and for other purposes.

Declares it to be congressional policy that: (1) a state has authority to manage the waters of rivers located within its boundaries; and (2) a state in which a Missouri River mainstem reservoir of the Corps of Engineers is located maintains authority to allocate the quantity of water in the reservoir attributable to the natural flows of the Missouri River within its boundaries. Requires all policies and procedures for the operations of Missouri River mainstem reservoirs of the Corps to be consistent with such policy.

Defines "natural flows" to mean Missouri River waters that would be flowing in a state in the absence of a dam that forms a Missouri River mainstem reservoir of the Corps. Requires the quantity of natural flows to be determined based on average monthly flows (excluding depletions) and to be calculated for the entire period of record, including before, during, and after construction of any dams or reservoirs.

Requires the Secretary of the Army to determine the quantity of water in each Missouri River mainstem reservoir of the Corps that is attributable to the natural flows of the Missouri River within the state in which the reservoir is located. Authorizes a state to seek judicial review of such determination.

Prohibits the Secretary from charging a fee in connection with water of the Missouri River in a state, without the state's consent, until such quantity of the natural flows of the Missouri River within the state is determined.