Greystone Reservoir Report

Last Updated: December 6, 2025

Greystone, a historic Rockfill dam located in North Providence/Johnston, Rhode Island, was completed in 1865 and stands at a height of 10 feet with a length of 355 feet.


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Summary

It sits on the Woonasquatucket River and has a storage capacity of 116 acre-feet, with a drainage area of 39 square miles. Despite its age, the dam is still in use and has a low hazard potential, but its condition has been assessed as poor as of October 2017.

The primary purpose of Greystone is not specified, but it serves as a vital structure for water resource management in the area. With a normal storage capacity of 81 acre-feet and a maximum discharge of 1039 cubic feet per second, the dam plays a crucial role in regulating water levels and preventing flooding in the surrounding region. Although it is privately owned and not state-regulated, the dam undergoes regular inspections to ensure its structural integrity and safety.

Greystone's presence on the Woonasquatucket River contributes to the overall resilience of the local water infrastructure. Despite its age and poor condition assessment, the dam continues to fulfill its functions effectively, highlighting the importance of ongoing maintenance and monitoring efforts for aging water resource structures. Enthusiasts of water resources and climate resilience will appreciate Greystone's historical significance and its role in protecting the community from potential risks associated with water management.

Year Completed

1865

Dam Length

355

Dam Height

7

River Or Stream

WOONASQUATUCKET RIVER

Primary Dam Type

Rockfill

Surface Area

13

Hydraulic Height

6

Drainage Area

39

Nid Storage

116

Structural Height

10

Hazard Potential

Low

Nid Height

10
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.