For a long time, officials advised people working in rivers after floods to remove logs and boulders that had piled up or to straighten out winding stream channels.
Now, taking lessons learned from Tropical Storm Irene and earlier, authorities with the Vermont Agency of Natural Resources suggest keeping the river “beautifully messy.”
“Going back to historical practice and historical paradigm, rivers were looked at as a problem that needed to be fixed,” said Rob Evans, rivers program manager for the Vermont Department of Environmental Conservation.
People often removed anything that kept rivers from being navigable — that prevented logs or canoes from being able to easily float down a channel.
“But that’s the problem,” Evans said. “We don’t need hydraulically efficient rivers. We need hydraulically inefficient rivers.”
Over time, officials have learned that rivers best recover from flooding when they’re left alone or touched as little as possible by the human hand (read: big, yellow machines). When river corridors are dredged or forced into smaller, straighter channels, they begin to function more like pipes, blasting water from one point to another, Evans said. Over decades, the legacy of “cleaning” rivers in Vermont has made water more fast and powerful during floods.
Instead, when logs are allowed to pile up, they slow the water. When streams are allowed to spread out into wetlands or wide floodplains, the water deposits silt and sediment, saving waters downstream — such as Lake Champlain — from receiving large volumes of silt.
Already, Vermont has been subject to a “legacy of channelization practices” that energize the rivers, Evans said, making them faster, more powerful and more dangerous.
In certain places across Vermont, people dredged streams after Tropical Storm Irene in 2011, causing more problems in the long term.
“It kind of exacerbated the flooding downstream,” said Will Eldridge, aquatic habitat biologist with the Vermont Fish & Wildlife Department. “And then, from a habitat perspective, we’re still recovering. Those fish populations are still recovering from all that work that happened after Irene.”
In one notable episode after Irene, as Vermont Public Radio reported in 2012, then-Secretary of Natural Resources Deb Markowitz chided her boss, then-Gov. Peter Shumlin, for making what she characterized as “‘dig-baby-dig’ type statements” about removing obstructions from rivers. Markowitz said those comments “inspired Vermonters to help out in ways that ultimately are very costly not just to the ecosystem but to the infrastructure.”
Historically, Vermonters and people across the country removed debris in rivers after flooding because they thought it would help fish move again. In reality, they were taking away habitat that can help fish stay protected from fast and high waters, and recover from the flooding.
Even now, Eldridge said, Fish & Wildlife is helping to rebuild some of the habitat that was lost due to dredging after the 2011 flooding.
Pockets of slowed water within log jams “create refuge for fish during floods,” Eldridge said. “That’s where fish are going to hang out and find protection when these high flows, these storms come through. It’s critical for them.”
A program called “Rivers and Roads” has been advising people who work where roads meet rivers — officials with the the Vermont Agency of Transportation and those who work on road crews, for example — to keep river corridors natural as much as possible.
But Eldridge said there hasn’t been a concerted effort to inform landowners about best practices when it comes to work in the river.
Landowners need a permit to conduct most types of debris removal, Evans said. He encouraged anyone contemplating changes to contact the Department of Environmental Conservation.
“If you don’t have to do anything in the river to protect human investments and infrastructure,” Evans said, “then leave it alone. That’s really what we’re advocating for.”
Read the story on VTDigger here: Logs in the river? Keep them there, Vermont officials advise..