Blackwells Mills Dam

Millstone River· Somerset, New Jersey· Earth· 20 ft tall
Significant Hazard Flood Risk Reduction Local Government

Key Takeaway

Blackwells Mills Dam is classified as significant hazard in New Jersey. Its primary use is flood risk reduction. Significant hazard means failure could cause economic or environmental damage. Learn more.

Physical Details

Dam Height 20 ft (taller than 72.4% in NJ)
Dam Length500 ft
Dam TypeEarth
Normal Storage10 acre-ft
Surface Area1 acres
Drainage Area1 sq mi
NID IDNJ00923

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: September 21, 2021
State Regulated: Yes
Regulatory Agency: NJDEP

Ownership

Township of Hillsborough

Local Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Blackwells Mills Dam?

Blackwells Mills Dam 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 Blackwells Mills Dam?

Blackwells Mills Dam is owned by Township of Hillsborough (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

What is the primary purpose of Blackwells Mills Dam?

Blackwells Mills Dam 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 Blackwells Mills Dam?

Blackwells Mills Dam has a dam height of 20 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 Blackwells Mills Dam last inspected?

Blackwells Mills Dam was last inspected on September 21, 2021. 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.