Lower Derby
Lower Derby is an earth dam located in Adams County, Colorado, built in 1942. It carries a Significant hazard potential classification.
About Lower Derby
The primary purpose of Lower Derby is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Rocky Mountain Arsenal (federal).
The dam stands 20 feet tall and stretches 3,000 feet across, creates a reservoir covering 80 acres, has a maximum storage capacity of 1,230 acre-feet, and collects water from a drainage area of 10 square miles. Completed in 1942, the structure is well-established, with more than 75 years of service.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. The most recent inspection on record was 07/01/2005. That was over 20 years ago.
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Location
| State | Colorado |
| County | Adams |
| Nearest City | Commerce City |
| Coordinates | 39.81515, -104.84586 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 20 ft |
| Dam Height | 20 ft |
| Dam Length | 3,000 ft |
| Year Completed | 1942 (84 years old) |
Storage & Hydraulics
| NID Storage | 1,230 acre-ft |
| Max Storage | 1,230 acre-ft |
| Normal Storage | 550 acre-ft |
| Surface Area | 80 acres |
| Drainage Area | 10 sq mi |
| Max Discharge | 15,500 cfs |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Rocky Mountain Arsenal |
| Owner Type | Federal |
| Hazard Classification | Significant |
| Condition Assessment | Not Available |
| Last Inspection | 07/01/2005 |
| Emergency Action Plan | No |
Identifiers
| NID ID | CO01902 |
| Federal ID | CO01902 |
| More Info | State Dam Safety Program |