Ish #3 (East Dam)

LITTLE THOMPSON RIVER-OS· Boulder, Colorado· Earth· 12 ft tall
Significant Hazard Irrigation Fish And Wildlife Pond Private

Key Takeaway

Ish #3 (East Dam) is classified as significant hazard in Colorado. Its primary use is irrigation. Significant hazard means failure could cause economic or environmental damage. Learn more.

Physical Details

Dam Height 12 ft (taller than 11% in CO)
Dam Length2,760 ft
Dam TypeEarth
Max Storage9.1K acre-ft
Normal Storage7.1K acre-ft
Surface Area314 acres
Drainage Area1 sq mi
Max Discharge3,066 cfs
NID IDCO02831

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: July 10, 2020
State Regulated: Yes
Regulatory Agency: DWR

Ownership

THE ISH RESERVOIR COMPANY

Private

Nearby Dams

Divide

Boulder, CO

Low Hazard 8 ft

Ish #3 (Main Dam)

Larimer, CO

High Hazard 42 ft

Walker

Boulder, CO

Low Hazard 8 ft

Baxter

Weld, CO

Low Hazard 8 ft

Branith #1

Boulder, CO

Low Hazard 13 ft

Rockwell

Weld, CO

Low Hazard 16 ft

Pleasant Valley

Boulder, CO

High Hazard 19 ft

Crystal

Boulder, CO

Low Hazard 11 ft

Frequently Asked Questions

What is the hazard classification of Ish #3 (East Dam)?

Ish #3 (East Dam) 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 Ish #3 (East Dam)?

Ish #3 (East Dam) is owned by THE ISH RESERVOIR COMPANY (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

What is the primary purpose of Ish #3 (East Dam)?

Ish #3 (East Dam) serves the following purposes: Irrigation, Fish And Wildlife Pond. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Ish #3 (East Dam)?

Ish #3 (East Dam) has a dam height of 12 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 Ish #3 (East Dam) last inspected?

Ish #3 (East Dam) was last inspected on July 10, 2020. 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.