Westerly council advances modified ‘E’ plan for Potter Hill Dam after hours of testimony

The Westerly Town Council voted on Oct. 21 to advance a modified version of “Alternative E” for the Potter Hill Dam site, directing consultants and staff to continue refined design, property-owner outreach and regulatory review under a NOAA-funded fish-passage grant.

The decision followed a multi-hour hybrid meeting that opened with procedural items and then moved into extensive public comment and a technical presentation by engineering firm Fuss & O'Neil. The firm recapped three primary approaches it had examined: full dam removal (Alternative A), removal with riffle/weir features (Alternative B) and a lower-impact boulder-weir approach (Alternative E). After modeling that showed even small downstream increases in the 100-year flood elevation could trigger a FEMA conditional letter-of-map-revision (CLOMAR), the firm developed incremental options labeled E1 and E2 that reduce downstream increases while limiting upstream headpond drops.

“Dam removal is the NOAA preferred alternative for improving fish passage,” the presenter said, summarizing the grant parameters and noting that NOAA funding can pay for removal and fish-passage work but not for repairing an existing dam structure. The team said E1 would avoid the need for a CLOMAR during the 100-year event but could leave small increases for lesser storms; E2 further limits increases across a wider set of flood events and reduces the baseflow headpond drop to roughly 2.6 feet in the conceptual design described to the council.

Residents, land trust representatives and technical experts filled the public-comment portion, pressing the council on wells, wetlands, sediment mobilization and PFAS risk from the Bradford Dye area. “Who will pay for ongoing periodic water quality testing and for how long?” asked Marie Ward, one of several residents who said private wells could be affected. Multiple speakers urged exploration of built fishway alternatives and additional studies before the council commits to removal-oriented designs.

Fuss & O'Neil presented recent field work to address those concerns: monitoring wells and dataloggers deployed along River Road and other sites, a limited groundwater investigation to link river and water-table elevations, PFAS surface-water and sediment sampling that did not find EPA-regulated PFAS compounds across the general riverbed (with elevated concentrations localized in the Bradford Dye discharge channel), and geomorphic/sediment assessments. The firm said its hydraulic modeling used an unsteady-state approach to better capture time-varying flood interactions and that it had adapted the FEMA-provided model with project-area topographic data.

Councilors asked detailed questions about when E1/E2 were developed, the expected headpond drops, how many private wells might require replacement and whether other grant programs (for example NRCS) could fund a structural fishway instead of dam removal. Engineers answered that well-replacement needs depend on the selected alternative and on completed well surveys; they said they had made repeated attempts to collect property-owner data and would continue targeted outreach to fill gaps.

After discussion the council voted to move forward with a modified Alternative E — described repeatedly in the meeting as a tuned, permit-focused variant of E/E2 that aims to avoid a CLOMAR-level downstream increase while still improving fish passage and providing some upstream flood reduction. The council directed staff to continue data collection, to work with Lighthouse Consulting on small-group stakeholder meetings, and to proceed with permitting conversations with FEMA and DEM.

The motion does not finalize a design; it advances further engineering and outreach to refine the geometry, finalize construction materials and confirm funding and permitability. The consultants told the council they expect initial Lighthouse-facilitated stakeholder meetings to be scheduled in November or December, with additional refinement and data collection continuing thereafter.

What’s next: the project team will prioritize filling remaining well-survey data gaps, continue sediment and wetland assessments, coordinate with federal and state permitting authorities about CLOMAR and other requirements, and run engineering refinements to reduce downstream flood impacts while preserving fish passage efficiency. The council’s action starts a focused, funded phase of outreach and design rather than a final commitment to a specific constructed alternative.