The Salton Sea at the edge of the Imperial Valley was used by the US military for bomb tests in the 1940s; in the fifties and sixties it was opened up to tourists and reinvented as the Californian Riviera. Fertilizer run-off from the nearby farms caused the lake's ecosystem to begin collapsing in the 1970s. Since then all the facilities and towns located on its shores have become entirely derelict. The lake's continuing desiccation and the resulting release of toxic particulate matter puts the Salton Sea at risk of becoming one of the biggest health hazards in US history.