Why is the dam being removed?

Dams can negatively impact the ecology of rivers and surrounding ecosystems by reducing habitat quality, altering ecological processes, and contributing to species population fragmentation. Removal of the Potter Hill Dam will both restore this section of the Pawcatuck River to its natural free-flowing state and mitigate flood hazard risks and flood damages to both upstream and downstream residents and structures along the river.

The Potter Hill Dam was first evaluated by the state as being structurally compromised in 1993, and its condition has only gotten worse since that time. Removing the dam will eliminate the risk of the dam and/or millrace channel headgates from breaching in the future. If this were to happen, the entire upstream length of the river impoundment (about 6 miles) could be suddenly released in an uncontrolled manner, causing damage to downstream properties and fish and wildlife habitats, and potential loss of water supply to residents in Hopkinton with shallow groundwater wells that are immediately adjacent to the river. Both the dam and debris from the mill are imminent hazards to boaters and downstream properties, including bridges and other public infrastructure. The Town of Westerly seeks to eliminate this hazard and potential liability by removing the dam expeditiously. Increased frequency of high rainfall events attributed to climate change are more and more commonly occurring, and increasing flood hazards and risks will continue until the dam is removed and the river is restored.

The dam is the last barrier on the main stem of the Pawcatuck River to upstream fish migration as the existing fish ladder is outdated and ineffective due to the poor location of the fishway entrance and the limited functioning of the fishway within an excessively small range of river flows (which will only worsen with climate change). Currently, migrating fish are delayed below the dam as they attempt to navigate the downstream river channel in search of the fish ladder entrance. With this delay, the fish become easy prey to cormorants, gulls, osprey and other predators. While this is a natural process, the loss of high numbers of spawning fish limits recovery of the river populations of herring and shad. Diadromous fish from the Pawcatuck River are a food source for important marine recreational and commercial species downstream. Improving fish passage will increase the use of nursery habitat in the Pawcatuck, which will in turn provide Little Narragansett Bay, Rhode Island Sound, and the Western North Atlantic with a greater number and diversity of fish. The local fishing economy will benefit as a result by having greater numbers of species such as striped bass, bluefish, and black sea bass.

In 2019, the Wood-Pawcatuck River watershed was designated as a Wild and Scenic River under the federal Wild and Scenic Rivers Act. Of the country’s 3.6 million miles of streams, less than 1% have received this designation. Removing the dam will improve the river’s ecological integrity, quality, and resilience, and will enhance recreational and aesthetic values of the river, thus improving the health and value of the Wood-Pawcatuck River watershed as a whole.

Removing the dam will provide significant flood risk reduction benefits to upstream properties and roadway infrastructure while reducing downstream flood risks due to dam failure. The project is consistent with the Town’s 2020-2040 Comprehensive Plan, the Town’s Municipal Resiliency Plan and the 2017 Wood Pawcatuck Watershed Association Flood Resiliency Plan.

Show All Answers

1. Why is the dam being removed?
2. Could the dam be repaired or partially removed?
3. Could a design similar to that of the Bradford fish passage project be used for the Potter Hill project?
4. What alternative designs have been considered and why was the proposed design selected?
5. What safety hazards are associated with the mill and dam structures?
6. How will removing the dam affect water levels in the river?
7. Will my household well be affected?
8. Many properties along the Pawcatuck River have private drinking water wells, especially on the Hopkinton side of the river. How many homeowners’ wells could be affected by the predicted drop
9. Will Westerly’s municipal water wells adjacent to the Pawcatuck River be affected?
10. How will removing the dam reduce flood risk to upstream and downstream properties? Will larger flood events (i.e., the 500-year recurrence flood) be worse upstream or downstream following dam removal?
11. Will removal of the dam cause increased flooding to downstream areas, including downtown Westerly?
12. How will removing the defunct dam and mill affect public access to and uses of the river?
13. How will removing the dam affect fish and wildlife?
14. How will removing the dam affect wetland systems upstream of the dam?
15. Is the proposed design accounting for climate change projections and worst-case future hydrologic scenarios?
16. Who is the project team?
17. What are the next steps?
18. Where can I get more information on the project?