Could a design similar to that of the Bradford fish passage project be used for the Potter Hill project?

Not all dams are the same. The unique hydrologic features of (and infrastructure in or over) each river requires thorough engineering assessments to evaluate options to address defunct and failing dams. In the case of the Potter Hill Dam, several options were evaluated before it was decided that removing the dam and restoring the river to its natural state is the best option in terms of improving the ecology of the river and reducing flood risks due to flooding to Westerly, Hopkinton, and Pawcatuck, CT.

The Potter Hill Dam is characterized by a narrow-length spillway with high spill and leaking gate structure. Immediately downstream of the dam, the river widens, and multiple millrace channels within the crumbling mill structure are present that release flows back into the river. The construction of a NLF would require a set of large stone weirs, for which a design would need to take into account this wide downstream section of the river.

To design and construct a full-height series of NLF weirs that will not only provide effective fish passage but also maintain current headpond levels, such as the system used for the Bradford project, would require a larger impact footprint, greater wetland disturbance, and the need to import a significant amount of fill material into the river to construct the step-pool system. Regulatory permitting agencies including the Rhode Island Department of Environment Management’s Freshwater Wetlands Division and the U.S. Army Corps of Engineers require the “least environmentally damaging project alternative” (LEDPA) that meets the project purpose(s) be implemented. The Town of Westerly and its project partners consider dam removal as the LEDPA for the Potter Hill dam, based on detailed engineering analyses completed to date.

In addition, the cost of this type of fishway would be greater to construct than the other alternatives considered and would require long-term maintenance and repair. The Town of Westerly will not be responsible for the operations and maintenance of such structures at the Potter Hill site.

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?