It was once hailed as a "miracle in the desert". Now the Salton Sea is an ecological disaster.

California's largest lake often looks like an ocean - it covers about 375 sq miles and is home to many migrating birds.

But the inland sea is saltier than the Pacific Ocean and is slowly dying from its own salinity - and the agriculture run-off which sustains it.

It was once a playground for the rich. But the towns that line its shore today suffer some of the highest unemployment rates in the US.

Saving the sea could cost billions of dollars. But, as the BBC's Alastair Leithead found out when he visited the area, it could cost more to do nothing.