Whale Rock
Whale Rock is an earth dam located in San Luis Obispo County, California, built in 1960. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Whale Rock
The primary purpose of Whale Rock 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 Whale Rock Commission (public utility). It impounds the Old Creek near Cayucos.
The dam stands 193 feet tall and stretches 850 feet across, creates a reservoir covering 594 acres, has a maximum storage capacity of 40,662 acre-feet, and collects water from a drainage area of 20 square miles. Completed in 1960, 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 01/28/2025.
At 193 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 | San Luis Obispo |
| Nearest City | Cayucos |
| River/Stream | Old Creek |
| Coordinates | 35.44780, -120.88700 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 193 ft |
| Dam Height | 193 ft |
| Dam Length | 850 ft |
| Year Completed | 1960 (66 years old) |
Storage & Hydraulics
| NID Storage | 40,662 acre-ft |
| Max Storage | 40,662 acre-ft |
| Surface Area | 594 acres |
| Drainage Area | 20 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Whale Rock Commission |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 01/28/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00029 |
| Federal ID | CA00029 |
| More Info | State Dam Safety Program |