Two Bay Area rival cities are participating in a friendly civic competition to clean up neighborhoods and waterways. “The Battle for the Bay,” is part of the annual California Coastal Cleanup Day, during which volunteers around the state pick up trash, restore habitats and plant trees, among other things. The contest is a nod to the 30th anniversary of the 1989 World Series between the San Francisco Giants and the Oakland A’s. The competition between San Francisco and Oakland is scheduled for September 21st from 9 a.m. to noon. It will hinge on which city can recruit the most volunteers, collect the most trash and have the most creative projects.