In the aftermath of the Oroville Dam incident, the State of California now requires all dam owners to create an Emergency Action Plan. As the EAP states, “The purpose of this EAP is to reduce the risk of loss of human life or injury, and to minimize property damage in the event of a potential or actual emergency situation associated with Senior Canyon Dam (CA01019). These situations include, but are not limited to dam instability, sizable earthquakes, extreme storm events, major spillway releases, overtopping of the dam, outlet system failure, vandalism or sabotage, spillway failures, and failure of the dam.”
While the Department of Water Resources has rated Senior Canyon Dam as “High Hazard,” that rating is not related to the condition of the dam, including the risk of failure. The rating is based on the downstream hazard potential were the dam to fail while operating with a full reservoir. According to the DSOD, “This hazard is not related to the condition of the dam or its appurtenant structures.” While a “High Hazard” rating means that at least one human life could be expected to occur should the dam fail when the reservoir is full, since the Senior Canyon Dam’s DSOD condition assessment is “Satisfactory,” acceptable performance is expected under all loading conditions. More than one-half of California’s 1,246 state-regulated dams have a “High Hazard” designation because of their proximity to human life and property.