What is the timing for forwarding a wild and scenic river study report authorized under Section 5 to Congress?

The study report for a congressionally authorized Section 5(a) study river is required to be forwarded by the study agency within the period specified in Section 5(b). This study report must be forwarded to Congress no matter what the outcome of the study.

Unlike the firm deadlines established for Section 5(a) study reports, the Act is silent in regard to Section 5(d)(1) rivers. Thus the river-administering agencies have considerable latitude in how and when to transmit the study report for rivers they have found suitable and are recommending to Congress for designation. The decision to forward such study reports may be delayed pending: 1) an appropriate aggregation of river recommendations into omnibus legislation; 2) the opportunity to add a single or multiple river bill to other agency federal legislation; or 3) development of a local/national constituency and/or congressional support.

Source
Interagency Wild & Scenic Rivers Council