Mcswain

Merced River· Mariposa, California· Built 1966· Rockfill· 97 ft tall
High Hazard Hydroelectric Irrigation Recreation Public Utility

Key Takeaway

Mcswain is classified as high hazard in California. It was completed in 1966 and is 60 years old. Its primary use is hydroelectric. 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 97 ft (taller than 81.5% in CA)
Dam Length1,620 ft
Dam TypeRockfill
Max Storage9.7K acre-ft
Normal Storage8.3K acre-ft
Surface Area310 acres
Drainage Area1,054 sq mi
Max Discharge250,000 cfs
Year Completed1966 (60 years old)
NID IDCA00242

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: August 8, 2023
State Regulated: Yes
Regulatory Agency: DWR, Safety of Dams

Ownership

Merced Irrigation District

Public Utility

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Mcswain?

Mcswain 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 Mcswain?

Mcswain is owned by Merced Irrigation District (Public Utility). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Mcswain built?

Mcswain was completed in 1966, making it 60 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 Mcswain?

Mcswain serves the following purposes: Hydroelectric, Irrigation, Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Mcswain?

Mcswain has a dam height of 97 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 Mcswain last inspected?

Mcswain was last inspected on August 8, 2023. 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.