To establish US Army Corps of Engineers standards for management of the Missouri River mainstream reservoirs and to authorize a Basin States Damage Fund.

Directs the Secretary of the Army to operate the Missouri River mainstem reservoir system to minimize adverse environmental and economic impacts to authorized uses on the Missouri River and mainstem reservoir system insofar as such operation does not conflict with provisions of the Flood Control Act of 1944 regarding the uses of water of certain States for navigation. Provides that if an authorized use is being adversely impacted or threatened with adverse impact by the operation of the system, the Secretary, upon request, shall change operations to prevent or mitigate the adverse impacts if the environmental and economic impact on the State or tribe outweigh any potential adverse impacts arising from the changes. Provides that if the Secretary denies a request, he or she shall document the reasons.

Authorizes appropriations to be deposited into the Missouri River Basin States Damage Fund established to mitigate impacts in the Missouri River Basin States incurred when operational adjustments have been denied or implemented under this Act.