 | This article needs to be updated. (March 2019) |
 View of Oroville Dam's main spillway (center) and emergency spillway (top), February 11, 2017. The large gully to the right of the main spillway was caused by water flowing through its broken and damaged concrete surface. | |
| Date | February 2017 |
|---|---|
| Location | Oroville Dam |
| Coordinates | 39°32′33″N 121°29′31″W / 39.5426°N 121.4920°W |
| Cause | High rainfall |
In February 2017, heavy rainfall damaged Oroville Dam's main and emergency spillways, prompting the evacuation of more than 180,000 people living downstream along the Feather River and the relocation of a fish hatchery.
Heavy rainfall during the 2017 California floods damaged the main spillway on February 7, so the California Department of Water Resources stopped the spillway flow to assess the damage and contemplate its next steps. The rain eventually raised the lake level until it flowed over the emergency spillway, even after the damaged main spillway was reopened. As water flowed over the emergency spillway, headward erosion threatened to undermine and collapse the concrete weir, which could have sent a 30-foot (10 m) wall of water into the Feather River below and flooded communities downstream. No collapse occurred, but the water further damaged the main spillway and eroded the bare slope of the emergency spillway.