An urgent evacuation has been ordered in northern California after officials said the US’s tallest dam had been weekend by heavy rain.<br /><br /> People living in flood risk areas have been told to leave immediately. It is feared the spillway on the Lake Oroville Dam could collapse at any moment.<br /><br /> Incredibly helpful graphic for those of us trying to understand what's happening. #OrovilleDam https://t.co/IppjFhvh1l pic.twitter.com/b90TClucgS— Tim Grieve (@timgrieve) February 13, 2017<br /> <br /><br /> It’s not clear how many residents are affected, but the local sheriff’s office has been using social media to stress the evacuation was not a drill.<br /><br /> BREAKING: At least 130,000 people asked to evacuate over concerns California's Oroville Dam's emergency spillway could fail.— The Associated Press (@AP) February 13, 2017<br /> <br /><br /> .ButteSheriff issued an Immediate Evacuation Order at 4:20 pm due to the #spillway incident for the area shown on the map. CA_DWR pic.twitter.com/b7lX9FHkJd— Butte County, CA (@CountyofButte) February 13, 2017<br /> <br /><br /> Engineers are are using helicopters to drop rocks to fill in gaps in the spillway while releasing water to lower the lake’s level.<br />
