Cross-border water pollution between Tijuana and South San Diego is not new, but in recent years, the problem has grown worse. The reasons are complicated: There is Tijuana’s topography, with its steep hillsides and canyons that drain towards the border; the factories that get away with illegal dumping; the city’s rapid population growth, aging wastewater infrastructure and inadequate garbage collection. In the U.S., funding cuts to the Environmental Protection Agency have prevented improvements to the Borderlands’ sewage system.