Lake Isabelle

S F ST VRAIN CREEK· Boulder, Colorado· Built 1925· Rockfill· 38 ft tall

Key Takeaway

Lake Isabelle is classified as low hazard in Colorado. It was completed in 1925 and is 101 years old. Its primary use is irrigation.

Physical Details

Dam Height 38 ft (taller than 79.2% in CO)
Dam Length0 ft
Dam TypeRockfill
Max Storage738 acre-ft
Normal Storage594 acre-ft
Surface Area36 acres
Drainage Area2 sq mi
Max Discharge1,262 cfs
Year Completed1925 (101 years old)
NID IDCO01929

Safety Information

Low Hazard

No probable loss of human life and low economic/environmental losses expected.

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

Emergency Action Plan: No
Last Inspection: September 24, 1990
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 Lake Isabelle?

Lake Isabelle is classified as Low Hazard. No probable loss of human life and low economic/environmental losses expected. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Lake Isabelle?

Lake Isabelle 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 Lake Isabelle built?

Lake Isabelle was completed in 1925, making it 101 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 Lake Isabelle?

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

How tall is Lake Isabelle?

Lake Isabelle has a dam height of 38 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 Lake Isabelle last inspected?

Lake Isabelle was last inspected on September 24, 1990. 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.