With its 18 million inhabitants, Los Angeles belongs to one of biggest cities on earth. All these people need water – water which in reality does not exist in the Californian Desert. The original Los Angeles River rises as a little torrent in the San Fernando Valley. Since it does not bring enough water, a huge aqueduct has been carrying water from the Owens Valley to this region, for 200 years. Over a distance of 370 kilometres – a true historic show of strength of engineering. Struggles for power and money have been fought for these waters, many Hollywood films tell these stories. Meanwhile, the Los Angeles River has degenerated to a flood relief channel and a sewage duct, and it flows on its entire length in a meanwhile famous concrete bedding across the metropolis. This will change.