Rock Island

Black River· Lewis, New York· Built 1984· Concrete· 18 ft tall

Key Takeaway

Rock Island is classified as low hazard in New York. It was completed in 1984 and is 42 years old. Its primary use is hydroelectric.

Physical Details

Dam Height 18 ft (taller than 49.5% in NY)
Dam Length180 ft
Dam TypeConcrete
Max Storage50 acre-ft
Normal Storage50 acre-ft
Surface Area8 acres
Drainage Area429 sq mi
Max Discharge18,500 cfs
Year Completed1984 (42 years old)
NID IDNY12231

Safety Information

Low Hazard

No probable loss of human life and low economic/environmental losses expected.

Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?

Emergency Action Plan: No
Last Inspection: September 19, 2019
State Regulated: Yes
Regulatory Agency: NYS DEC

Ownership

Not Listed

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Rock Island?

Rock Island is classified as Low Hazard. No probable loss of human life and low economic/environmental losses expected. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Rock Island?

Rock Island is owned by information not available (Not Listed). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Rock Island built?

Rock Island was completed in 1984, making it 42 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 Rock Island?

Rock Island serves the following purposes: Hydroelectric, Fire Protection, Stock, Or Small Fish Pond. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Rock Island?

Rock Island has a dam height of 18 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 Rock Island last inspected?

Rock Island was last inspected on September 19, 2019. 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.