Really twisted, I know, but couldn't resist the metaphor. This is part of the trash dump that has become the Tijuana River watershed right at the US-Mexican border. As it typical of many under-developed countries in Latin America and around the world, trash collection in impoverished areas, which are often found alongside rivers, seems to not be a priority. Heavy rains wash all of the trash, raw sewage and disease from Tijuana into the US since this portion of the river flows to the north across the border.