Slack Reservoir Reservoir Report

Last Updated: December 6, 2025

Located in Smithfield, Rhode Island, Slack Reservoir is a private water resource that serves as a recreational hub for residents and visitors alike.


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Summary

The reservoir, completed in 1885, boasts a masonry dam standing at 17 feet high and stretching 220 feet in length. With a normal storage capacity of 1300 acre-feet and a maximum storage of 1780 acre-feet, Slack Reservoir covers a surface area of 150 acres and is fed by the Stillwater River-tributary.

Despite its historical significance and recreational value, Slack Reservoir poses a high hazard potential with a poor condition assessment as of October 2017. The reservoir is regulated by the state of Rhode Island, with inspection, permitting, and enforcement protocols in place to ensure public safety. With a maximum discharge of 100 cubic feet per second and a spillway width of 6 feet, Slack Reservoir remains a key water resource in Providence County, Rhode Island.

For water resource and climate enthusiasts, Slack Reservoir offers a fascinating insight into the intersection of historical infrastructure, recreational activities, and environmental risk management. As one of the oldest reservoirs in the state, its maintenance and upkeep are essential to ensure the safety of surrounding communities and the preservation of this valuable water source. Despite its challenges, Slack Reservoir continues to be a popular destination for outdoor enthusiasts and serves as a reminder of the importance of sustainable water resource management in the face of changing climate patterns.

Year Completed

1885

Dam Length

220

Dam Height

15

River Or Stream

STILLWATER RIVER-TRIB

Primary Dam Type

Masonry

Surface Area

150

Hydraulic Height

14

Drainage Area

2

Nid Storage

1780

Structural Height

17

Hazard Potential

High

Nid Height

17
       
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.