Lower Derby

Adams, Colorado· Built 1942· Earth· 20 ft tall
Significant Hazard Irrigation Fish And Wildlife Pond Water Supply Federal Government

Key Takeaway

Lower Derby is classified as significant hazard in Colorado. It was completed in 1942 and is 84 years old. Its primary use is irrigation. Significant hazard means failure could cause economic or environmental damage. Learn more.

Physical Details

Dam Height 20 ft (taller than 36.1% in CO)
Dam Length3,000 ft
Dam TypeEarth
Max Storage1.2K acre-ft
Normal Storage550 acre-ft
Surface Area80 acres
Drainage Area10 sq mi
Max Discharge15,500 cfs
Year Completed1942 (84 years old)
NID IDCO01902

Safety Information

Significant Hazard

No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities.

Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?

Emergency Action Plan: No
Last Inspection: July 1, 2005
State Regulated: Yes
Regulatory Agency: DWR

Ownership

Rocky Mountain Arsenal

Federal Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Lower Derby?

Lower Derby is classified as Significant Hazard. No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Lower Derby?

Lower Derby is owned by Rocky Mountain Arsenal (Federal Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Lower Derby built?

Lower Derby was completed in 1942, making it 84 years old. Many U.S. dams were built between the 1930s and 1970s during a period of major infrastructure investment.

What is the primary purpose of Lower Derby?

Lower Derby serves the following purposes: Irrigation, Fish And Wildlife Pond, Water Supply. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Lower Derby?

Lower Derby has a dam height of 20 ft. Dam height is measured from the natural streambed at the downstream toe to the top of the dam, and may differ from the visible height.

When was Lower Derby last inspected?

Lower Derby was last inspected on July 1, 2005. Inspection dates indicate when a formal review occurred, not the results of that inspection.

Data from the National Inventory of Dams (NID) maintained by the US Army Corps of Engineers. Dam conditions may have changed since the last update. This site is not affiliated with USACE. Do not use for emergency planning — contact your local dam safety program.