Officials warn against excess dredging during flood recovery

State officials are urging locals not to dredge rivers during flood recovery efforts without guidance and permits from the Vermont Agency of Natural Resources.

Dredging has long been used as a strategy to clear debris from streams and rivers after heavy rains, but it “comes with significant risk and so (it) needs to be used thoughtfully,” said Julie Moore, the agency’s secretary, at a Tuesday press conference.

“Our predecessors used big yellow machines and dynamite to relocate our rivers,” Moore said. “But with our changing climate, this is no longer a sustainable approach, if it ever was.”

Moore added that because Vermont has seen “more frequent and more intense storms” in recent years, it’s necessary to keep rivers as intact as possible so they don’t become more dangerous in future flooding events.

“The most common issue after a flood is over-dredging of rivers or excessive streambank filling,” according to a Sunday press release from the state Agency of Natural Resources. “Over-dredging or over-filling creates a much more unstable river which threatens adjacent property and infrastructure during the next flood.”

Rivers best recover from flooding when they’re left alone or manipulated as little as possible, according to previous reporting from VTDigger . When river corridors are dredged or forced into new channels, they begin to function more like pipes, making water more fast and powerful as it moves downstream.

But when logs and other debris pile up in waterways, they slow floodwaters, allowing them to spread out into wetlands and floodplains — and dump their silt and sediment there, rather than in other waterways. Leaving rivers untouched is better for wildlife, too, especially for fish that rely on fallen trees for protection against fast, high waters.

But Moore said the agency’s dredging precautions are “not about fish habitat or water quality” but rather “about public safety.”

“How we treat our waterways that flow through our communities has real implications for, and can present real risk to, each of us as well as those who live downstream,” Moore said.

The safety risk of fast-moving rivers, she said, is why the Agency of Natural Resources needs to regulate the “numerous calls and inquiries” it receives about dredging rocks, logs and sediment out of local rivers and streams.

Municipalities can only dredge rivers without authorization if the project qualifies as an emergency protective measure — defined by the Department of Environmental Conservation as work done to “preserve life or protect property from severe damage.” For example, if debris is redirecting the flow of a river toward homes or businesses, work undertaken to clear the river would be considered an emergency protective measure, according to the DEC’s guide to post-flood river recovery .

Emergency measures taken must be “minimized to (those) necessary to protect life and property” and must be reported to DEC officials within 72 hours, according to the department.

If rivers require non-emergency dredging, municipalities must obtain a permit and coordinate projects with regional river managers , according to the Agency of Natural Resource’s press release.

Moore said the agency has approved more than 400 such projects since last July’s floods because dredging is an important river management strategy to maintain rivers’ channel capacity — it’s just not the only one.

“Dredging will not solve flooding, but it is a tool to help alleviate flooding in certain circumstances,” she said.

The larger solution to addressing future flooding, Moore said, is to improve rivers’ access to floodplains across the state, especially in areas hit hardest by river flooding.

Some Vermont communities have already started this work, she said. Northfield’s Water Street Park, for example, serves as an “intentional” space that water can expand into during floods. Tens of thousands of cubic yards of material were removed from the area after more than a dozen FEMA buyouts, she said, reestablishing a floodplain that can protect the rest of Northfield from floodwater.

“The most effective way to have room for our floodwaters is by setting aside and restoring places for waters to spread out, as opposed to digging deeper,” she said.

Read the story on VTDigger here: Officials warn against excess dredging during flood recovery .