Clark Mills (Pa-490)

CALVIN CLARK RUN· Mercer, Pennsylvania· Built 1971· Earth· 45 ft tall
High Hazard Flood Risk Reduction Local Government

Key Takeaway

Clark Mills (Pa-490) is classified as high hazard in Pennsylvania. It was completed in 1971 and is 55 years old. Its primary use is flood risk reduction. 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 45 ft (taller than 81.2% in PA)
Dam Length430 ft
Dam TypeEarth
Max Storage790 acre-ft
Normal Storage19 acre-ft
Surface Area4 acres
Drainage Area3 sq mi
Year Completed1971 (55 years old)
NID IDPA00246

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: September 10, 2020
State Regulated: Yes
Regulatory Agency: Pennsylvania Department of Environmental Protection

Ownership

MERCER COUNTY COMMISSIONERS

Local Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Clark Mills (Pa-490)?

Clark Mills (Pa-490) 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 Clark Mills (Pa-490)?

Clark Mills (Pa-490) is owned by MERCER COUNTY COMMISSIONERS (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Clark Mills (Pa-490) built?

Clark Mills (Pa-490) was completed in 1971, making it 55 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 Clark Mills (Pa-490)?

Clark Mills (Pa-490) serves the following purposes: Flood Risk Reduction. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Clark Mills (Pa-490)?

Clark Mills (Pa-490) has a dam height of 45 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 Clark Mills (Pa-490) last inspected?

Clark Mills (Pa-490) was last inspected on September 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.