MOCCASIN LOWER - CA00122-3257
Dam Name: MOCCASIN LOWER
State: CA
Downstream Hazard Potential: H
Incident Type: Non-Failure
Incident Date: 03/22/2018
Incident Driver: Other
Incident Mechanism 1: Insufficient Spillway Capacity
Incident Mechanism 2Reservoir Overfilling
Incident Mechanism 3Spillway Erosion/Head Cutting
Incident IDCA00122-3257
Incident DescriptionBlockage of Moccasin Creek Bypass Tunnel caused sudden rise of the reservoir above core wall to nearly the dam crest because of insufficient spillway capacity. More in Remarks.
Named Hydrologic Event
EAP Enacted (Y/N) due to IncidentYes
Fatalities (Number)0
Number of People Evacuated20
Number of Habitable Structures Evacuated1
Number of Habitable Structures Flooded1
Other Infrastructure ImpactsWater/sewer lines
Economic Damages (in $)$25 million to $50 million
ResponseImmediate response by dam owner, Division of Safety of Dams, and first responders.
Volume released at failure (ac-ft)
Additional Remarks or UpdatesFish Hachery immediately downstream was evacuated - likely less than 20 people
Owner TypeL
Dam TypeRE
Primary Purpose(s)HOS
EAPY
Dam Height60 ft
Max Storage (ac-ft)554.00
Surface Area (acres)29.00
Year Completed1930
NID NumberCA00122
River NameMOCCASIN CREEK
Latitude37.8123
Longitude-120.306
Year Modified
Regulatory Agency(ies)DWR, SAFETY OF DAMS
Incident Time
Incident Duration2 days
Incident Report ProducedYes
Information SourcesCA DSOD
