Upper Twin Lake

Robinson Creek· Mono, California· Built 1905· Earth· 14 ft tall
High Hazard Water Supply Irrigation Private

Key Takeaway

Upper Twin Lake is classified as high hazard in California. It was completed in 1905 and is 121 years old. Its primary use is water supply. High hazard means loss of life is likely if the dam fails — it does not indicate the dam's current condition. Learn more.

Physical Details

Dam Height 14 ft (taller than 6.7% in CA)
Dam Length160 ft
Dam TypeEarth
Max Storage2.1K acre-ft
Surface Area286 acres
Drainage Area30 sq mi
Year Completed1905 (121 years old)
NID IDCA00643

Safety Information

High Hazard

Loss of human life is likely if the dam fails.

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

Emergency Action Plan: Yes
Last Inspection: November 14, 2022
State Regulated: Yes
Regulatory Agency: DWR, Division of Safety of Dams

Ownership

Centennial Livestock

Private

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Upper Twin Lake?

Upper Twin Lake is classified as High Hazard. Loss of human life is likely if the dam fails. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Upper Twin Lake?

Upper Twin Lake is owned by Centennial Livestock (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Upper Twin Lake built?

Upper Twin Lake was completed in 1905, making it 121 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 Upper Twin Lake?

Upper Twin Lake serves the following purposes: Water Supply, Irrigation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Upper Twin Lake?

Upper Twin Lake has a dam height of 14 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 Upper Twin Lake last inspected?

Upper Twin Lake was last inspected on November 14, 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.