Westlake Reservoir
Westlake Reservoir is an earth dam located in Los Angeles County, California, built in 1972. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Westlake Reservoir
The primary purpose of Westlake Reservoir is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by Las Virgenes Municipal Water District (public utility). It impounds the Tree Springs Cr near Westlake.
The dam stands 158 feet tall and stretches 1,400 feet across, creates a reservoir covering 156 acres, has a maximum storage capacity of 9,200 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1972, the structure is well into its service life at over 50 years old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 03/20/2025.
At 158 feet, this dam is taller than 99% of all dams in the United States.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The California dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | California |
| County | Los Angeles |
| Nearest City | Westlake |
| River/Stream | Tree Springs Cr |
| Coordinates | 34.13280, -118.83260 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 158 ft |
| Dam Height | 158 ft |
| Dam Length | 1,400 ft |
| Year Completed | 1972 (54 years old) |
Storage & Hydraulics
| NID Storage | 9,200 acre-ft |
| Max Storage | 9,200 acre-ft |
| Surface Area | 156 acres |
| Drainage Area | 0 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Las Virgenes Municipal Water District |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 03/20/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00904 |
| Federal ID | CA00904 |
| More Info | State Dam Safety Program |