What protections are afforded a river authorized for study under Section 5(a) of the Wild & Scenic Rivers Act and for how long?

A river authorized for study under Section 5(a) of the Wild & Scenic Rivers Act is subject to the conditions and restrictions specified in Sections 7(b), 8(b), 9(b), and 12(a) of the Act.

The river is protected for the duration of the study plus up to three years after the required report is submitted (along with the President’s recommendation) to Congress. Should Congress not act within the three-year time frame, the river is no longer afforded protection by the Wild & Scenic Rivers Act. In cases where a study has not been submitted to Congress, the statutory protections remain in effect.

Source
Interagency Wild & Scenic Rivers Council