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?

Flood risks will decrease upstream of the dam, especially for properties bordering the river near and downstream from the Route 3 bridge. As noted in the March 18 public information meeting, 100-year flood elevations in this portion of the river will be lowered between 1.3 and 2.5 feet, depending on the location of the property. This will reduce the potential for flood damage during 100-year floods for residences on Lima Drive, Forest Drive, Saratoga Avenue, Hiscox Road, Boy Scout Drive and Fieldstone Way in Westerly, and along Laurel Street, Maxson Street, and River Road in Hopkinton.

Elevations for all river flow events (normal, 100-year flood and larger floods) downstream of the dam will not increase following removal of the dam. The magnitude of pre- and post- dam removal water surface elevations decreases as the magnitude of flows associated with any particular seasonal or storm flow event increases. As shown by modeling analysis results presented during the March 18 public information meeting, there are more significant changes (reductions) in water surface elevations at respective locations upstream of Potter Hill Dam following its removal during lower flow conditions (e.g., seasonal low flow) in comparison to higher flow conditions (normal spring flows, 100-year flood flows, and higher flow events).

As a result, there will still be reductions in upstream flood elevations during a 500-year flood, but they will be less significant than 100-year event reductions. In terms of changes to downstream flood elevations, there will be no changes to downstream flood risks for the 500-year flood event or any other flood event following removal of the dam.

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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?