California authorities ordered the evacuation of nearly 200,000 residents in the eastern Sacramento Valley on Sunday. After heavy rains, the Oroville Dam emergency spillway was used for the first time after the damn began operating over capacity. But on Sunday, engineers discovered a large hole in the emergency spillway caused by erosion. The primary spillway was also found to have significant erosion problems earlier last week. Evacuations were ordered due to concerns that the eroded spillway could allow overflows of the downstream channels.