Copperopolis
Copperopolis is an earth dam located in Calaveras County, California, built in 1905. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Copperopolis
The primary purpose of Copperopolis 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 William (huei) And Tina Chang (private). It impounds the Penney Creek near Copperopolis.
The dam stands 33 feet tall and stretches 600 feet across, creates a reservoir covering 24 acres, has a maximum storage capacity of 225 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1905, the structure is over a century 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 04/16/2025.
At 33 feet, this dam is taller than 78% of dams nationwide.
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 | Calaveras |
| Nearest City | Copperopolis |
| River/Stream | Penney Creek |
| Coordinates | 37.98310, -120.64950 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 33 ft |
| Dam Height | 33 ft |
| Dam Length | 600 ft |
| Year Completed | 1905 (121 years old) |
Storage & Hydraulics
| NID Storage | 225 acre-ft |
| Max Storage | 225 acre-ft |
| Surface Area | 24 acres |
| Drainage Area | 1 sq mi |
Ownership & Safety
| Purpose | Water Supply |
| Owner | William (Huei) and Tina Chang |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 04/16/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00845 |
| Federal ID | CA00845 |
| More Info | State Dam Safety Program |