Upper Derby is an earth dam located in Adams County, Colorado, built in 1942. It carries a Significant hazard potential classification.
Dam profile
NID height · 15 ft15 ft tall and 1,400 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Upper Derby
The primary purpose of Upper Derby 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 Rocky Mountain Arsenal (federal).
The dam stands 15 feet tall and stretches 1,400 feet across, creates a reservoir covering 87 acres, has a maximum storage capacity of 620 acre-feet, and collects water from a drainage area of 9 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 07/01/1983. That was over 43 years ago.
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Location
| State | Colorado |
| County | Adams |
| Nearest City | Commerce City |
| Coordinates | 39.81744, -104.83516 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 15 ft |
| Dam Height | 15 ft |
| Dam Length | 1,400 ft |
| Year Completed | 1942 (84 years old) |
Storage & Hydraulics
| NID Storage | 620 acre-ft |
| Max Storage | 620 acre-ft |
| Surface Area | 87 acres |
| Drainage Area | 9 sq mi |
| Max Discharge | 40 cfs |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Rocky Mountain Arsenal |
| Owner Type | Federal |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 07/01/1983 |
| Emergency Action Plan | No |
Identifiers
| NID ID | CO01285 |
| Federal ID | CO01285 |
| More Info | State Dam Safety Program |