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Foss: Role of dam in flooding merits scrutiny

Foss: Role of dam in flooding merits scrutiny

Retired architect might be most vocal advocate
Foss: Role of dam in flooding merits scrutiny
Scotia resident James Duggan has been researching the Lock 7 dam for years.
Photographer: Marc Schultz

The dam at Lock 7 is impressive. It is a massive, even imposing, concrete structure that spans the Mohawk River and hearkens back to the heyday of the Erie Canal. Built in 1913, the structure is more than 30 feet high and almost 2,000 feet in length. 

It's also immovable — the dam cannot be raised or lowered, which means it cannot release water before heavy storms. 

Does this lack of movable parts cause water to back up and make parts of Schenectady County, such as the Stockade and the area around Schenectady County Community College, more likely to flood? 

According to Scotia resident James Duggan, a retired architect, the answer is yes.

Duggan has been researching the Lock 7 dam for years, and he's in the process of finalizing a paper that uses U.S. Geological Survey data on water flow to bolster his argument. 

It's not a new argument — but that doesn't mean we shouldn't revisit it. 

In fact, now might be the ideal time for taking a closer look at Duggan's research. 

In September, the city of Schenectady released its final draft of new flood-mitigation guidelines, which focus on how to protect the Stockade from floodwaters. 

These guidelines discuss moving and raising homes, and other adjustments, such as moving mechanical and electrical systems out of the basement to more elevated parts of the house and infilling basements. 

WEB LOCK7openweekend_0.jpg

Given the considerable investment it would take to implement these guidelines, and the disruption to the Stockade that would result, it's worth asking whether there are other, less disruptive ways to address the problem of flooding in Schenectady's flood-prone areas

Retrofitting the Lock 7 dam wouldn't be cheap or easy — but neither would retrofitting, raising and moving all of the at-risk homes in the Stockade. 

At the very least, Duggan's idea merits further study — something that hasn't really been done. 

Duggan might be the most vocal advocate for taking a closer look at whether the design of the Lock 7 dam contributes to Schenectady's flood problems, but there are others who share his belief, or at least think it's a sensible thesis that should be studied more formally. 

"Yes, the idea that Lock 7 affects flooding in the Schenectady pool (Lock 7 to Lock 8) is reasonable and needs to be investigated," said John Garver, a Union College professor of geology who also coordinates the Mohawk Watershed Symposium, an annual event that highlights river-related issues. 

In an email to me, Garver noted that after the flooding caused by Irene and Lee in 2011, the state Canal Corporation adopted a new flood-preparation readiness plan that "involves opening the movable locks in anticipation of big flood waters. 

This means that in the event of flooding, the movable locks up river (8,9,10,11,12) are opened, and thus hold back less water. This is new, and it means that Lock 7 (properly the Vischer Ferry Dam) gets all that extra water, all at once. The other locks/dams have traditionally served to slow flood waters, especially when they all act in concert together. Now, the VFD is all on its own." 

Duggan believes the Lock 7 dam suffers from a fatal design flaw and that it needs to be retrofitted with gates that can be lifted and dropped to release water and relieve pressure. 

"Other dams can do this," Duggan told me. "They can drain. ... We need to create some sluice, some new channel that can increase velocity and slope."  

After Irene and Lee, eight upstate dams were rebuilt so that they could be opened prior to floods. But the Vischer Ferry Dam wasn't damaged in those storms, and was thus ineligible for the federal funding that supported this work. 

Which is interesting — if there's a case to be made for retrofitting those eight other upstate dams, it seems like there might be a case to made for retrofitting the Vischer Ferry Dam, too. 

The state Canal Corporation owns the Lock 7 dam, but because it powers a hydroelectric plant, it falls under the purview of the New York Power Authority. 

I reached out to the NYPA for comment on Duggan's research, but an agency spokesman declined. 

In the past, NYPA has said that there are no plans to retrofit the dam, and no evidence that doing so would reduce flooding in Schenectady. 

Duggan isn't the first to lobby for structural changes to the Lock 7 dam, and he's unlikely to be the last. 

People have been raising questions about the design of the dam since it was built over a century ago, and flooding in Schenectady appeared to worsen. 

A 1914 editorial in the Schenectady Union-Star proclaimed, "The promise of State engineers that the stationary dams along the Mohawk would not bring flood havoc have proven false. The worst has materialized." In 1925, engineers blamed the dam for exacerbating flood events. 

I am not an engineer or a hydrologist, and I do not know whether the Vischer Ferry Dam exacerbates flooding or not. 

But Duggan and Garver make a strong case for at least investigating the issue. 

They would both like to see the state conduct its own, more comprehensive analysis of the dam's impact on flooding, and I would, too. 

Until a more formal study is done, questions about the dam will linger and almost certainly resurface the next time it floods. 

Reach Gazette columnist Sara Foss at [email protected]. Opinions expressed here are her own and not necessarily the newspaper's. Her blog is at https://dailygazette.com/blogs/thinking-it-through.

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