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Experts differ over role of ice jams in Stockade flooding

Experts differ over role of ice jams in Stockade flooding

Viewpoints aired at Mohawk Watershed Symposium
Experts differ over role of ice jams in Stockade flooding
An ice-jammed Mohawk River as seen from Rexford looking toward the Rexford Bridge, Feb. 7, 2018.
Photographer: PETER R. BARBER

Experts agree that ice jams along the Mohawk River have led to the flooding that has long plagued the watershed. 

But several key stakeholders studying the issue have broken over the extent to which flooding in the Stockade neighborhood can be specifically attributed to the obstructions.

“Our long-term research has suggested about 80 percent of flooding in the Stockade is driven by ice jams," Union College geology professor John Garver said at Friday. “It’s the really the main thing we need to worry about and remediate."

Tropical Storm Irene caused massive flooding in 2011, and ice jams have led to more limited amounts in the years since, including a historic 17-mile jam last year that flooded several streets in the historic neighborhood, forcing some residents from their homes.

MULTIPLE FACTORS

Garver has been studying ice jams in the Mohawk River for the last two decades.

Since 2009, he's been bringing together experts to share the latest findings on watershed-related issues as part of the Mohawk Watershed Symposium, where participants at this year's installment sped through their presentations at a blistering clip on Friday.

“A Stockade solution must deal with ice jam flooding," Garver said.

But a consulting firm tasked with researching options for long-term mitigation solutions in the flood-prone Stockade isn’t sold on his 80 percent figure. 

“That is something we need to talk about and confirm,” said Margaret Irwin, project manager with River Street Planning & Development. 

Irwin said flooding can be attributed to multiple factors, including heavy weather events. 

Pinning down the precise causes is critical before coalescing on potential solutions, whether elevating homes or building berms. 

“One of those [causes] needs to be seen as a dominant force, and that needs to happen sooner rather than later,” Irwin said.

About 60 homes are located in the 100-year floodplain bounded by Front Street, the railroad and Cucumber Alley.

DAMS IN FOCUS

Regardless of how much of the Stockade's issues can be attributed to ice jams, data continues to emerge on how precisely the massive formations are created.

Garver pointed at bottlenecks that tend to form near Rexford Knolls behind the Vischer Ferry Dam as a result of sediment build-up that constricts the flow of the river during heavy weather events.

“I think that’s one of those things causing jams,” he said.

The conference brought together numerous academics, researchers, consultants, engineers and other stakeholders to discuss their latest findings on the subject.

He joined his colleagues by stressing his job was simply to gather and interpret data — not advocate or lobby for any specific solution.

But when pressed by an audience member when asked if it would be possible to widen the choke points — and which entity would be responsible for doing so — he said the state Canal Corporation, the agency that controls the series of locks along the Mohawk, could be a key player in remediation efforts.

“If the Vischer Ferry Dam was completely removed, it would certainly reduce the amount of sheer ice, for sure,” Garvey said, referring to the dam at Lock 7, which is unique among structures because it does not contain movable parts to allow for controlled release of water ahead of flooding events.

ZOOMING OUT

Milone & MacBroom is also studying flood-mitigation efforts and collecting data as part of a broader state-funded project to study 48 flood-prone streams and rivers in 29 counties.

Project manager Mark Carabetta said the reason for flooding varies in different places.

But dam removal has proven to reduce downstream flooding, he said, citing the removal of a dam along the Boquet River in the Adirondack town of Willsboro in 2015.

His firm will ultimately issue a report containing recommendations. 

“What kinds of recommendations will we be making at this point? I can’t say. It’s just getting underway,” Carabetta said. 

Options could hypothetically range from anything from “operational changes” at dams to channel alterations.

There is no magic bullet for everyone, he said. And ultimately, many businesses and homes may have little choice but to “relocate, reallocate, flood-proof.”

An attendee who identified himself as a Stockade resident asked Carabetta how much data was reasonably needed before stakeholders ultimately decided on a plan. 

“We’re going to be collecting data over the next several months,” Carabetta said. 

Models require a “predictable and finite amount of data," he said. 

As for changes: “There needs to be funding and the political will to make those things happen,” he said. “I can’t say if those things will be implemented or not."

The State Department of Environmental Conservation (DEC) announced last year it would spend $500,000 to conduct a flooding and ice jam study for the 147-mile main channel of the Mohawk River to pinpoint high-risk areas and identify solutions.

The Mohawk River Basin Action Agenda for 2019-2022, which will also address invasive species and water quality, will be released this year.

“We hope to have it out really soon," said Eric Weigert, DEC Mohawk River Basin Program director and research scientist, at the conference on Friday.

WORKSHOP UPCOMING

Back in the Stockade, Irwin estimated her firm's analysis will be completed by June. 

All options are on the table when it comes to developing a comprehensive flood-mitigation plan, City of Schenectady officials have said, from constructing flood walls and berms, using deployable gates during flood events or elevating buildings.

Irwin said the process is complex because no blueprint exists to guide mitigation efforts in historic neighborhoods like the Stockade. 

River Street and the City of Schenectady will brief residents on their progress at a multi-day workshop on April 1, 3 and 4 at the First Reformed Church at 8 North Church St. 

Irwin said stakeholders aim to select a strategy by December, identify specific solutions by March 2020 and submit final plans to FEMA for review and approval by June 2020. 

FEMA will consider giving the city approximately $7.5 million for the second phase, she said, which would include the construction of new infrastructure. 

Irwin cautioned that the sum was relatively small.

“We need to figure out the best practical solution for use of those dollars,” she said.

— Steve Williams contributed reporting

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