What is the legal requirement before a TFR can be implemented for a river closure?

The correct answer highlights the procedural requirements for implementing a Temporary Flight Restriction (TFR) for a river closure. A TFR must be signed and put in place before any official river closure occurs. This step is crucial to ensure that all necessary legal and safety protocols are followed, providing a structured approach to managing activities in and around the waterway. The implementation of a TFR also ensures that relevant authorities are notified and engaged in the process, which is necessary for coordinating efforts to protect public safety and manage navigation effectively. By having the TFR signed first, it establishes an official status that can be communicated to all relevant parties, ensuring compliance with regulations.

Other options suggest scenarios that do not align with legal protocols. For instance, having a river closed before the signing of a TFR undermines the regulatory process, as it would bypass necessary notifications and approvals. Similarly, maintaining a closure indefinitely without a TFR would violate the requirement for proper authorization. Finally, submitting a TFR after the river has already been closed would not provide the required legal framework for the closure, making it ineffective and potentially exposing the authorities to liability. Overall, following these protocols is critical for effective waterways management and ensures safety for all stakeholders involved.