Bob Dylan going electric at Newport’s sister festival gets all the lore, but Muddy Waters beat him to the plugged-in punch by five years. At the height of the folk revival, the Chicago electric-blues icon brought an amped-up, scarifying-ly powerful combo into Newport Jazz Festival. Between Waters’ bull-roar voice, stinging guitar and swinging band, nobody could stand still, not even Muddy — during “I’ve Got My Mojo Working,” he left the mike long enough to do a twirl with harmonica player James Cotton as the crowd shrieked. For a finale, poet Langston Hughes wrote “Goodbye Newport Blues” on the spot, and pianist Otis Spann sang it because Waters was too worn out from “Mojo” to sing anything further. At Newport quickly became a guidebook for young blues-rock enthusiasts: Keith Richards and Mick Jagger were among those paying close attention. David Menconi