Middlebury seeks river security
EAST MIDDLEBURY — The village of East Middlebury was evacuated, basements were swamped, bridge abutments were exposed and the critical floodwall below Grist Mill Bridge was compromised in the flooding from Tropical Storm Irene rains on Aug. 28. Fortunately, East Middlebury didn’t suffer the kind of crippling blow from Irene that Rochester, Hancock, Granville and many other towns got.
But what if it had?
That’s the concern of East Middlebury residents and local officials looking to prevent future catastrophe along the Middlebury River — a complex task that must balance the natural power of a river with interests of local residents.
The Middlebury selectboard will begin developing a committee at their Tuesday meeting. The group will focus on creating a plan for dealing with this river corridor.
River scientist and East Middlebury resident Amy Sheldon — who has conducted extensive watershed studies of the Middlebury River — and Town Planner Fred Dunnington shed light on this issue from a planning, science and history perspective, and they take a look at how the town might proceed.
“If one lives by a river it’s almost not a question of if (your residence will) be damaged by flooding, it’s a question of when,” said Dunnington. “If we had as intensive a rainfall event, with as long a duration as they had in southern Vermont, East Middlebury could expect similar damage. There could be many houses lost … I think we owe it to residents of the area and emergency providers … to study (the river) and put the best available knowledge to this at a higher level of scrutiny.”
The Middlebury River springs up high in the Green Mountains and bottoms out onto the floor of the Champlain Valley in East Middlebury. There, explained Sheldon, its energy and sediment dissipates, creating a particularly dynamic stretch of stream.
For more than a century, the river was mined for resources. Just like all streams, it naturally wanted to fill back in. When it was straightened and narrowed for energy and transportation purposes, the river wanted to return to its natural width, Sheldon explained.
“The river has a natural tendency to establish what we call an equilibrium condition,” said Sheldon. “When we actively manage our rivers, we’re constantly fighting the desires of the river to be in its equilibrium. That’s the crux of where we get conflict.”
For decades, explained Sheldon, the state actively managed Vermont’s rivers on a yearly basis. The costs were high and the state was constantly fighting against each river as it tried to reach equilibrium. More than two decades ago, the state moved in a different direction, banning gravel extraction in rivers — except for permits that allowed some towns and individual property owners to extract 50 cubic yards — and allowing the rivers to reach a more balanced state where they can access their flood plain.
“What the science community came to realize is that over the long-term, continuing to manage the rivers is expensive for the state and also not great for the environment,” said Sheldon. “Over the last 20 years, river management came into being because of this recognition: We’re not managing our rivers well, so what do we need to do to work with the natural tendencies of the river to reduce the conflicts.”
Now, as many streambeds have filled in, Sheldon thinks that the rivers need to be reassessed.
“OK, we’ve had 25 years of aggradation (filling in). The rivers are about to access their flood plain. What does that mean to our infrastructure? Let’s methodically plan for that,” she said. “My hope is that the people of East Middlebury are ready to do that, and we can figure out where we need to intervene and where we can let the river maintain itself. Because wherever it can maintain itself, it’ll be a healthier, more stable river and a less expensive endeavor.”
At a special selectboard meeting on Oct. 27 — sparked by citizen controversy as well as state and federal scrutiny of the town’s river practices — many East Middlebury residents pleaded for continued dredging, concerned they might fall victim to future flooding. Town officials said they weren’t legally permitted to do more river work, and as Sheldon explained, dredging without extensive understanding of a particular stretch of river can create an adverse affect.
“The risk … is that when you dredge and straighten rivers you increase the energy, and yes you threaten the downstream property owners, but potentially you can cause a head cut that can propagate upstream and erode the abutments of the bridge that you were trying to protect.”
What will protect the town, said Sheldon, is the river’s flood plain. It acts as a cushion from flooding. As long as the river has a place to release its energy and sediment — a place other than local properties — the town will be safe. Figuring out how to do that, however, will require a diverse group of experts.
Sheldon thinks a plan could be designed and implemented within 18 months.
To fund a hazard mitigation study, plan and project, Dunnington is looking to apply for a FEMA Hazard Mitigation Grant, which would provide assistance for such an undertaking.
“I think one of the more detailed studies we ought to do is what if we had a rainfall event of more intensity and longer duration. What would happen if there was 10 percent or 20 percent more water,” said Dunnington. “We need to anticipate hazards and take steps to prevent damage beforehand. You might open flood shoots on the south sides of the road that are obstructed … like they did up in Ripton.”
A study of the river, Sheldon said, would need to be multifaceted.
“What is the desired width of that channel? What’s the type of channel? Is it a channel that is mostly a transport channel? How do we manage our bridges long-term so that the town doesn’t need to go in every three years and fix the retaining wall? All of that has to go into how you actively manage a river,” she said.
In assembling a committee to get the study going, Dunnington said many views must be accounted for.
“The prescriptions that are appropriate have really yet to be fully informed by a variety of disciplines. I think the key is to have a group that has (many) interests represented,” he said. “There is a public participation part of this … You can’t do this in isolation from the people and the emotion. That’s part of this process.”
As Sheldon sees it, the best way to prepare for the future is to better understand the present.
“We have to take the information that we have and the experience we had after Irene and learn from it … We need to keep track of how much (certain infrastructure) costs us, and, at some point, we make a choice about the infrastructure we’re maintaining,” she said. “We need to say (the Route 125) curve costs us x number of dollars a year to maintain, does it make sense to keep maintaining it there? Or do we need to do something different with how we manage it? Or different in how we get to Ripton? And that’s a conversation that we can’t have because we don’t have the data. But it’s very clear that we’re spending an awful lot of money to maintain certain places where we have constant contact with our rivers.
“At some point you make a decision with your eyes open, instead of your eyes closed. And right now we’re making decisions with our eyes closed.”
Reporter Andrew Stein is at firstname.lastname@example.org.