The Los Angeles River is the large ditch which cuts through Los Angeles from the Sepulveda Basin to Long Beach, passing by Griffith Park, downtown, and North Hollywood.
Its headwaters are in the Santa Susana Mountains, the San Gabriel Mountains, and the Santa Monica Mountains. To date there are about 2 miles out of the whole thing that aren't concrete. There's been an effort to restore the river as of late but really, theres nothing left to save. People should have noticed instead that the Santa Ana River and other smaller watercourses in the area were currently being concreted themselves and lost forever. But people generally dont pay attention to things like that. The Sepulveda Basin had a pretty bad flood a while back, covering a park and some other areas in water. People fail to realize that these areas are meant to flood so the water doesnt rush into Los Angeles instead. Nevertheless, experts say that if we had a 100 year flood the river would probably end up rampaging through the streets of Los Angeles and Long Beach anyway. The Army Corps of Engineers wanted to raise the levee walls, but apparently didnt realize that if the river got above the level of the city, the water would backwash against the storm drains anyway, or at least the drains would stop working. This has happened before along the Dominguez Channel, another big ditch. But no one seems to notice that either.
This wonderful watercourse also serves as a nice sewer for the city, the water dumps directly into the ocean so anything anyone has dumped on any street of Los Angeles all summer comes pouring out into the ocean after the first good rain. Pleasant, eh?