Allen Lake

LEFT HAND CREEK-OS· Boulder, Colorado· Built 1928· Earth· 24 ft tall

Key Takeaway

Allen Lake is classified as significant hazard in Colorado. It was completed in 1928 and is 98 years old. Its primary use is irrigation. Significant hazard means failure could cause economic or environmental damage. Learn more.

Physical Details

Dam Height 24 ft (taller than 49.9% in CO)
Dam Length1,525 ft
Dam TypeEarth
Max Storage865 acre-ft
Normal Storage700 acre-ft
Surface Area36 acres
Drainage Area0 sq mi
Max Discharge8,821 cfs
Year Completed1928 (98 years old)
NID IDCO00169

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: Yes
Last Inspection: June 23, 2022
State Regulated: Yes
Regulatory Agency: DWR

Ownership

LEFT HAND DITCH COMPANY (TERRY PLUMMER)

Private

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Allen Lake?

Allen Lake 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 Allen Lake?

Allen Lake is owned by LEFT HAND DITCH COMPANY (TERRY PLUMMER) (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Allen Lake built?

Allen Lake was completed in 1928, making it 98 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 Allen Lake?

Allen Lake serves the following purposes: Irrigation, Fire Protection, Stock, Or Small Fish Pond, Recreation, Water Supply. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Allen Lake?

Allen Lake has a dam height of 24 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 Allen Lake last inspected?

Allen Lake was last inspected on June 23, 2022. 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.