Flood — Butte, California

2017-02-12 to 2017-02-13 · near Honcut, Butte, California

Event narrative

A mass evacuation of over 180000 people located downstream of Oroville Dam was ordered for a possible flash flood, due to the projected near failure of the emergency spillway. The emergency spillway was used when the main spillway was discovered to have suffered severe erosion during releases back on and around February 7th. Releases from Lake Oroville had been increased due to rising lake levels due to inflow from heavy rains.

A presidential disaster declaration provided $274 million for emergency response costs from Feb. 7 though the end of May. The money targeted stabilizing the emergency and main spillways, as well as debris removal and work on the downed Hyatt Powerplant. A bid for long term repairs to the spillway was accepted at $275 million. Together, these total $549 million, though final costs could be much higher.

Wider weather episode

Additional heavy rain brought widespread flooding of small streams and rivers, with some flooding of main stem rivers. Wet conditions from previous storms brought saturated ground and elevated reservoirs, with flood control releases. Reduced releases at Oroville Dam resulted in the use of the emergency spillway for the first time in the dam's history. A portion of the emergency spillway began to show signs of failure which resulted in NWS Sacramento to issue a Flash Flood Warning for potential dam failure and the Oroville Sheriff to issue mandatory large scale evacuations. The emergency spillway was utilized because the main spillway had damage that required reduced flows through it. Several levee breaks also brought local evacuations.

There was also mountain snow many feet deep, and damaging winds, with numerous trees down on roads, vehicles, and homes. Many roads, including major highways such as Interstate 80, were shut down due to mudslides, heavy snow, flooding, washouts or avalanche suppression. Other significant impacts include numerous accidents due to slippery roads, evacuations and rescues due to flooding.

View location on OpenStreetMap → (39.0276, -121.5346)

Source: NOAA Storm Events Database, event_id 682611. Narrative written by the NWS forecast office that issued the report.