Seph Mack

TR YELLOW CREEK· Indiana, Pennsylvania· Built 1987· Earth· 21 ft tall
Significant Hazard Recreation State Government

Key Takeaway

Seph Mack is classified as significant hazard in Pennsylvania. It was completed in 1987 and is 39 years old. Its primary use is recreation. Significant hazard means failure could cause economic or environmental damage. Learn more.

Physical Details

Dam Height 21 ft (taller than 46.9% in PA)
Dam Length305 ft
Dam TypeEarth
Max Storage15 acre-ft
Normal Storage9 acre-ft
Surface Area2 acres
Drainage Area0 sq mi
Year Completed1987 (39 years old)
NID IDPA01397

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: February 20, 2018
State Regulated: Yes
Regulatory Agency: Pennsylvania Department of Environmental Protection

Ownership

DCNR

State Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Seph Mack?

Seph Mack 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 Seph Mack?

Seph Mack is owned by DCNR (State Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Seph Mack built?

Seph Mack was completed in 1987, making it 39 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 Seph Mack?

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

How tall is Seph Mack?

Seph Mack has a dam height of 21 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 Seph Mack last inspected?

Seph Mack was last inspected on February 20, 2018. 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.