Water washing of boiler firesides shall only be accomplished after approval from whom?

The correct answer is NAVSEA because they are responsible for establishing technical standards and procedures for the maintenance and operation of naval facilities, including boilers. Water washing of boiler firesides is a significant maintenance procedure that can affect the operational capability and safety of the vessel. As such, it requires authorization from a competent authority that ensures compliance with naval policies and technical directives. NAVSEA’s involvement ensures that the procedure is carried out safely, effectively, and in accordance with the overarching guidelines relevant to the Navy's operations and maintenance practices.

The other options, while related to various aspects of naval operations, do not specifically possess the authority to approve such technical maintenance actions. Local Command and US Navy Regulations may provide guidance or oversight, but they defer to NAVSEA on matters concerning technical execution. The Environmental Protection Agency, being an external agency, deals with environmental regulations rather than specific procedural approvals for military maintenance activities.