From “Oroville Spillway Incident” – California Department of Water Resources website:
On February 7, erosion was noticed on the flood control spillway located adjacent to the Lake Oroville Dam. Department of Water Resources temporarily stopped outflow from the spillway to investigate the erosion. After testing and evaluation, outflow resumed from the flood control spillway to account for rising reservoir levels. Crews also began preparing for use of the emergency spillway… View full DWR incident information.