Federal Columbia River Power System Certainty Act This bill requires Federal Columbia River Power System (FCRPS) operations to be consistent with a specified decision. The system includes dams in the Columbia and Snake rivers in the Pacific Northwest. Specifically, the Bureau of Reclamation, the Bonneville Power Administration, and the U.S. Army Corps of Engineers must operate the FCRPS consistent with the Columbia River System Operations Environmental Impact Statement Record of Decision dated September 2020. The preferred alternative outlined in that decision would allow specified dams in the lower Snake River to remain in place. The decision may be amended if each agency determines that (1) changes are necessary for public safety or electrical grid reliability, or (2) certain requirements in the decision are no longer necessary. Further, the bill requires statutory authorization for any structural modification, action, study, or engineering plan that (1) restricts FCRPS hydroelectric dam generation; or (2) limits navigation on the Snake River in Washington, Oregon, or Idaho.