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Consultants find limited flood-reduction benefits from simple dredging; residents advocate river maintenance
Summary
Stone Environmental's modeling showed channel dredging alone produced little reduction in modeled flood levels and could increase velocities and erosion; residents recounted decades of dredging and urged channel maintenance or restoration as part of a multi-pronged approach.
Consultants told Richmond's special meeting that simple channel dredging produced little modeled reduction in water-surface elevation in the village and cautioned dredging can increase velocities and downstream erosion.
"When we ran removing sediment from the channel itself, we do not see a significant reduction in flood levels with that scenario," Megan Arpino said, and presenters noted dredging can raise river velocities and have potential downsides. The team also tested lowering Volunteer Green by about 8 feet in a scenario that produced up to a 1.3-foot reduction at Bridge Street and Esplanade but yielded a small increase near the wastewater treatment plant, illustrating trade-offs.
Several long-time residents recounted that river maintenance and dredging historically prevented some flooding and urged the town and state to allow more active sediment removal. One resident said dredging used to be performed regularly through the 1960s and argued it improved river health and stability. Consultants responded that while dredging can be part of multi-point solutions, the modeling did not show consistent flood-reduction benefits at the scale and locations tested, and regulatory and sediment‑management constraints apply.
The study will record dredging and process-based restoration as longer-term or complementary recommendations while prioritizing infra projects that produce clearer modeled benefits under the HMGP screening criteria.
