Demens Creek Debris Basin
Demens Creek Debris Basin is an earth dam located in San Bernardino County, California, built in 1980. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Demens Creek Debris Basin
The primary purpose of Demens Creek Debris Basin is debris control. The dam is designed to catch sediment, rocks, and debris carried by flowing water — particularly important in areas prone to mudslides or heavy erosion. The dam is owned by County Of San Bernardino Department Of Public Works (local government). It impounds the Demens Creek near Rancho Cucamunga.
The dam stands 35 feet tall and stretches 4,237 feet across, creates a reservoir covering 4 acres, has a maximum storage capacity of 35 acre-feet, and collects water from a drainage area of 2 square miles. Completed in 1980, the structure is 46 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 03/10/2025.
At 35 feet, this dam is taller than 82% 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 | San Bernardino |
| Nearest City | Rancho Cucamunga |
| River/Stream | Demens Creek |
| Coordinates | 34.15790, -117.60400 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 35 ft |
| Dam Height | 35 ft |
| Dam Length | 4,237 ft |
| Year Completed | 1980 (46 years old) |
Storage & Hydraulics
| NID Storage | 35 acre-ft |
| Max Storage | 35 acre-ft |
| Surface Area | 4 acres |
| Drainage Area | 2 sq mi |
Ownership & Safety
| Purpose | Debris Control |
| Owner | County of San Bernardino Department of Public Works |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 03/10/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA01278 |
| Federal ID | CA01278 |
| More Info | State Dam Safety Program |