From the BBC:
A failing dam is causing “extremely dangerous” flooding on a Puerto Rico river in the wake of Hurricane Maria, authorities say.The National Weather Service (NWS) said the “imminent failure” of the Guajataca Dam is a “life-threatening situation”. More than 70,000 people live in the nearby towns of Isabela and Quebradillas. At least 13 people have died since Maria ripped through Puerto Rico, knocking out power to the whole island. Operators of the Guajataca Dam said the structure, at the northern end of Lake Guajataca in northwest Puerto Rico, began to show signs of failing at 14:10 local time (18:10 GMT).