Oroville Disaster May Have Been Caused By Weak Soil Under Spillway

The destruction of Oroville Dam’s main spillway in February likely occurred because it was built on highly erodible rock, according to several experts interviewed by Water Deeply. If confirmed by a forensic investigation now underway, rebuilding the spillway will require a much more expensive and time-consuming effort. The Oroville spillway was ripped apart in February as California Department of Water Resources (DWR) released water from the dam to make room for heavy storm runoff into the reservoir. It’s an important reminder that no matter how carefully built and maintained a dam might be, it will always remain vulnerable to unknowns.