The Los Angeles River (also known as the L.A. River) starts in the Simi Hills and Santa Susana Mountains and flows through Los Angeles County, California, from Canoga Park in the western end of the San Fernando Valley, nearly 48 miles (77 km) southeast to its mouth in Long Beach. Several tributaries join the once free-flowing and frequently flooding river, forming alluvial flood plains along its banks. It now flows through a concrete channel on a fixed course. From Wiki
Three centuries ago, the Los Angeles River meandered through marshes and forests of willow and sycamore. Trout spawned in its waters and grizzly bears roamed its shores. The bountiful environment the river helped create supported one of the largest concentrations of Indians in North America. Today, the river is made almost entirely of concrete. Chain-link fence and barbed wire line its course. Shopping carts and trash litter its channel. Little water flows in the river most of the year, and nearly all that does is treated sewage and oily street runoff. On much of its course, the river looks more like a deserted freeway than a river. From the book The Los Angeles River: Its Life, Death, and Possible Rebirth (Creating the North American Landscape)
Los Angeles’ river, a long-neglected wasteland, is about to become an urban oasis: a linear, riparian Central Park.