As well as benefits hydroelectric dams have added dangers. Dams increase the risk of earthquakes, because the weight of the water-reservoir impacts the Earth’s crust underneath. [1] Moreover, big dams run the risk of bursting, causing massive damage in their wake. The bursting of the Chinese Banqiao dam in 1975 is estimated to have cost about 230,000 lives. [2]  [1] BBC News, ‘Earthquake risk from dams’, 2002  [2] The New Internationalist, ‘Big dams, big trouble’, 2003