General

• Region (Map) : ................... Mid-Pacific
• State (Map) ........................ California
• County ................................ San Luis Obispo
• Project: ................................ Santa Maria
• Dam type: ........................... Earthfill
• Location: ............................ 150 mi NW of LA
• Watercourse: ..................... Cuyama River
• Reservoir: ........................... Twitchell
• Construction Date: ........... 1956-1958
• National ID Number ......... CA10197
• Hydrologic Unit Code .....

Dimensions

• Crest Elevation of Dam: .....................    692.0 ft
• Structural Height of Dam: ..................    241.0 ft
• Crest Length: .......................................  1804.0 ft
• Top of Joint Use: .................................   623.0 ft
• Top of Active Conservation: ..............  623.0 ft
• Top of Inactive Conservation: ............  511.0 ft
• Spillway Crest: .......................................  651.5 ft
• Top of Dead Storage: ...........................  474.0 ft
• Streambed at Dam Axis : ....................... 476.0 ft

Hydraulics

• Normal Water Surface Elev:       ........... 623.0 ft
• Hydraulic Height: .................................. 210.5 ft
• Service Spillway Type:
•    Uncontrolled  Crest    ................................Yes
•    Morning-Glory ........................................... No
•    Crest Length    ........................................... NA
•    Gated      ....................................................... No
•    Capacity at Elev:   686.5 ft,              26,350 cfs
• Auxiliary Spillway ......................................... No
•     Capacity at Elev.   .................................. 0  cfs
• Outlet Works Capacity at
•     Elevation  651.5 ft,  ........................ 12,700 cfs

Hydrology

• Drainage Area: ...............................1135.0 sq mi
• Hydrometeorological Report               HMR 36
• Flood Type: ...........................Oct-May General
• Storm Duration: ....................................... 72 hrs
• Probable Maximum Flood (PMF) Report:
•   Peak Inflow: ................................... 229,350 cfs
•   Inflow Volume: ........................ 765,250 acre-ft
•   Flow Duration: ..................................12.3 days
•   PMF Routing MWS Elev.: ....................... NA
•   Initial Routing Elev: ............................ 623.0 ft
•   Study Date: ................................ January 1990