The Lake Attitash Association’s annual Grand Illumination and Boat Parade is scheduled for Saturday at the lake in Amesbury and Merrimac. Homes and docks on the lake are decorated with lights, flags, and other items during the event, said Veronica Wolfe, a member of the association’s board of directors. The event was first held in the early 1900s and features a parade around the lake with decorated boats, although undecorated boats are also welcome. The parade assembles at 6:30 p.m. near the state boat ramp in Merrimac off Route 110. The public is welcome to watch from the ramp.