Big Creek is an earth dam located in Tuolumne County, California, built in 1969. It carries a High hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 120 ft120 ft tall and 480 ft long, taller than 98% of U.S. dams with a recorded height. Height is drawn to scale against a ten-story building, about 100 ft; the profile is a generic embankment section and the water level is illustrative.
About Big Creek
The primary purpose of Big Creek 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 Pine Mountain Lake Association (private). It impounds the Big Creek near Groveland.
The dam stands 120 feet tall and stretches 480 feet across, creates a reservoir covering 200 acres, has a maximum storage capacity of 7,650 acre-feet, and collects water from a drainage area of 25 square miles. Completed in 1969, 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 10/21/2025.
At 120 feet, this dam is taller than 98% 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 | Tuolumne |
| Nearest City | Groveland |
| River/Stream | Big Creek |
| Coordinates | 37.85760, -120.20100 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 120 ft |
| Dam Height | 120 ft |
| Dam Length | 480 ft |
| Year Completed | 1969 (57 years old) |
Storage & Hydraulics
| NID Storage | 7,650 acre-ft |
| Max Storage | 7,650 acre-ft |
| Surface Area | 200 acres |
| Drainage Area | 25 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Pine Mountain Lake Association |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 10/21/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00652 |
| Federal ID | CA00652 |
| More Info | State Dam Safety Program |