According to the report, since 1998 the number of unsafe dams has risen by a third to more than 3,500.

The report does concede that federally owned dams are in good condition, but warns that $10.1 billion is needed over the next 12 years to address all critical non-federal dams. Many states have large numbers of unsafe dams, including Pennsylvania (725), New Jersey (583), and New Hampshire (357),” ASCE says, adding that the number of high-hazard potential dams is increasing dramatically from 9,281 in 1998 to 10,213, last year, and with 1,046 in North Carolina alone.

The ASCE also cites a study by the Association of State Dam Safety Officials which suggests the total investment to bring US dams into safety compliance or to remove obsolete dams tops $30 billion.

ASCE recommends establishing a comprehensive and fully funded dam safety programme in all 50 states, especially Alabama, the only state without an authorised dam-safety programme, and legislation to create a loan fund for the repair, rehabilitation and removal of non-federal dams.