20141210-5071 FERC PDF (Unofficial) 12/10/2014 11:53:13 AM

CEII-Critical Energy Infrastructure Information
Do Not Release
6.1.2

Candidate F2: PMF Event Occurring at Oroville Dam and Emergency Spillway is
Overtopping and Head-cutting Occurs Initiating at the Feather River

Candidate Description: A PMF flood event is occurring and over 10 feet of water is spilling
over the emergency spillway at Oroville Dam. Erosion begins where the flow is entering the
Feather River and progresses by head-cutting into the reservoir.
The adverse and positive factors related to Candidate F2 are provided in Table 6.2.
Table 6.2 Adverse and Positive Factors for Candidate F2
Candidate F2: PMF Event Occurring Oroville Dam and Emergency Spillway is
Overtopping and Head-cutting Occurs Initiating at the Feather River
Adverse Factors

Positive Factors
Broad area below emergency spillway
reduces energy of water.
Have had 50 years of flow occurring at the
downstream end of the FCO spillway
channel, and very little erosion has been
observed. A 150,000 cfs release through
the FCO has also occurred.
Distance from the Feather River to the
emergency spillway is approximately 3/4
mile.
The rock between the Feather River and
emergency spillway is very competent and
resistant to erosion.

Rationale for Not Carrying PFM forward: The failure of Oroville Dam through head-cutting
was not considered credible because of distance from the emergency spillway to the Feather
River (approximately 3/4 mile), the competence of the rock, and the lack of erosion that has
been observed at the end of the FCO spillway channel.

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