Ageing dams by region (IMAGE) Terry Collins Assoc Caption The problem of ageing large dams today confronts a relatively small number of countries -- 93% of all the world's large dams are located in just 25 nations led by China and the USA. Credit UNU-INWEH Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.