33 C.F.R. § 149.565
What are the required characteristics and intensity of lights on buoys used to define traffic lanes?
(a) The buoy's light color that defines the lateral boundaries of a traffic lane must comply with the buoy color schemes in § 62.25 of this chapter.
(b) The buoy light may be fixed or flashing. If it is flashing, it must flash at intervals of not more than 6 seconds.
(c) Buoy lights must have an effective intensity of at least 25 candela.