Marsh Creek
Marsh Creek is an earth dam located in Contra Costa County, California, built in 1963. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Marsh Creek
The primary purpose of Marsh Creek is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Contra Costa County Flood Control And Water Conservation District (local government). It impounds the Marsh Creek near Brentwood.
The dam stands 59 feet tall and stretches 1,540 feet across, creates a reservoir covering 335 acres, has a maximum storage capacity of 4,425 acre-feet, and collects water from a drainage area of 52 square miles. Completed in 1963, 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 01/07/2026.
At 59 feet, this dam is taller than 95% 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 | Contra Costa |
| Nearest City | Brentwood |
| River/Stream | Marsh Creek |
| Coordinates | 37.88830, -121.72160 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 59 ft |
| Dam Height | 59 ft |
| Dam Length | 1,540 ft |
| Year Completed | 1963 (63 years old) |
Storage & Hydraulics
| NID Storage | 4,425 acre-ft |
| Max Storage | 4,425 acre-ft |
| Surface Area | 335 acres |
| Drainage Area | 52 sq mi |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Contra Costa County Flood Control and Water Conservation District |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 01/07/2026 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA00809 |
| Federal ID | CA00809 |
| More Info | State Dam Safety Program |