Authorities issued evacuation orders for at least 188,000 people near northern California’s Lake Oroville Sunday after erosion at the emergency spillway threatened extreme flooding, CNN reports.
According to the outlet, a hole developed in the auxiliary spillway of the 770-foot-tall Oroville Dam, the tallest in the United States. Although the dam is still standing, the erosion could undermine the spillway’s structure, allowing rushes of water to wash downhill into nearby towns.
“I’m not going to lift the evacuation order until I have a better idea of what that means and what risk that poses,” Butte County Sheriff Kory Honea said in a news conference late Sunday night.
Officials also worked to increase the amount of water being released from California’s second-largest reservoir, as it was filled to the brim by rain and snowfall this winter after a six-year drought.
Dan Brekke of KQED told NPR’s Morning Edition, “The lake rose 50 feet in just a few days and got up to this emergency spillway which had never been used since the dam went into service in 1968. And on Saturday morning, it began pouring over there.”
— NWS Sacramento (@NWSSacramento) February 13, 2017
'THIS IS NOT A DRILL': Residents in areas of Oroville, Calif. ordered to evacuate as dam is predicted to failpic.twitter.com/b49uOFvDDt
— Breaking911 Nature (@B911Nature) February 13, 2017
— Gov. Brown Press Ofc (@GovPressOffice) February 13, 2017
California Governor Jerry Brown issued an emergency order, saying the state was directing all necessary personnel and resources to deal with a “complex and rapidly changing” situation.
The situation shifted late Sunday night, when acting Water Resources director Bill Croyle said water had finally stopped pouring over the dam’s emergency spillway. However, the cautioned that the situation remained unpredictable.