Sawpit Debris Basin
Sawpit Debris Basin is an earth dam located in Los Angeles County, California, built in 1955. It carries a High hazard potential classification and has a fair condition assessment.
About Sawpit Debris Basin
The primary purpose of Sawpit 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 Los Angeles County Department Of Public Works (local government). It impounds the Sawpit Wash near Monrovia.
The dam stands 82 feet tall and stretches 520 feet across, creates a reservoir covering 6 acres, has a maximum storage capacity of 152 acre-feet, and collects water from a drainage area of 2 square miles. Completed in 1955, 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 fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 09/15/2025.
At 82 feet, this dam is taller than 97% 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 | Los Angeles |
| Nearest City | Monrovia |
| River/Stream | Sawpit Wash |
| Coordinates | 34.16830, -117.99310 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 82 ft |
| Dam Height | 82 ft |
| Dam Length | 520 ft |
| Year Completed | 1955 (71 years old) |
Storage & Hydraulics
| NID Storage | 152 acre-ft |
| Max Storage | 152 acre-ft |
| Surface Area | 6 acres |
| Drainage Area | 2 sq mi |
Ownership & Safety
| Purpose | Debris Control |
| Owner | Los Angeles County Department Of Public Works |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 09/15/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CA01157 |
| Federal ID | CA01157 |
| More Info | State Dam Safety Program |