Drone video footage released Friday shows how construction progressed on the Lake Oroville main spillway from July 1 through July 6, 2017. The reconstruction of Oroville Dam’s flood-control spillways began in May, more than three months after a near disaster forced the emergency evacuation of thousands of downstream residents. Kiewit Corp. of Omaha, Neb., which was awarded a $275.4 million contract to fix the dam’s two spillways, has more than 200 employees on the site, a workforce that will balloon to 500 by August.