Muddy Run Main Dam

Susquehanna River· Lancaster, Pennsylvania· Built 1967· Rockfill· 260 ft tall
High Hazard Hydroelectric Public Utility

Key Takeaway

Muddy Run Main Dam is classified as high hazard in Pennsylvania. It was completed in 1967 and is 59 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 260 ft (taller than 99.2% in PA)
Dam Length4,800 ft
Dam TypeRockfill
Max Storage60.5K acre-ft
Normal Storage60.5K acre-ft
Surface Area1,000 acres
Drainage Area9 sq mi
Max Discharge20,000 cfs
Year Completed1967 (59 years old)
NID IDPA00266

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 20, 2022
State Regulated: No

Ownership

Constellation Energy Generation, LLC (NYRO)

Public Utility

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Muddy Run Main Dam?

Muddy Run Main Dam 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 Muddy Run Main Dam?

Muddy Run Main Dam is owned by Constellation Energy Generation, LLC (NYRO) (Public Utility). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Muddy Run Main Dam built?

Muddy Run Main Dam was completed in 1967, making it 59 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 Muddy Run Main Dam?

Muddy Run Main Dam serves the following purposes: Hydroelectric. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Muddy Run Main Dam?

Muddy Run Main Dam has a dam height of 260 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 Muddy Run Main Dam last inspected?

Muddy Run Main Dam was last inspected on August 20, 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.