Coronado’s tony seaside community and working-class Imperial Beach could be headed for a major reckoning with the sewage continuing to spill over the border from Tijuana. Beach closures that were once thought of as largely a wintertime occurrence now appear poised to become a year-round phenomena in San Diego’s South Bay. However, that’s not because the cross-border pollution from Baja California’s overtaxed and crumbling wastewater system has dramatically escalated, according to county officials. It’s because the ocean is more polluted than previously thought.