Why Dredging Won’t Solve Flooding

Since the floods of 2023, I have heard a very common question from folks: why aren’t we dredging the rivers? The thinking goes that river dredging would prevent future floods from happening. Unfortunately, dredging is not a long-term, sustainable solution to flooding.

Dredging a river refers to the practice of digging gravel and sediment out of a river channel, deepening it to theoretically provide a place for flood water to go. Vermont has a long history of river dredging–often, this practice was combined with gravel mining. People historically removed gravel and sediment from rivers to use on roads or to build riverbanks higher, theoretically making it more difficult for water to overtop them.

Advocates for dredging a river will sometimes use the metaphor of a bucket. If you have a bucket full of stones, you should empty out those stones so the bucket can hold more water. This metaphor is flawed because, unlike a bucket, a river is a system that is constantly changing and rebalancing its equilibrium. If you change one thing (dredge the river), it will create other problems.

Vermont DEC Rivers & Roads Tier 1 training

The graphic attached to this article illustrates what happens to a dredged river. In stage 2, the riverbed is cut down into the channel–imagine that this is from dredging. As the river is dug deeper, you trap the erosive force of the water in its channel. The force of the water begins to undercut the banks, which collapse. In stage 3, you can see the riverbanks collapsing. The river channel widens, and land and property are lost. By stage 5, the river has stabilized itself in response to dredging but has done so by eroding the land around it.

There are other practical considerations when it comes to dredging. In Irene, the Ottauquechee River rose to a peak of 14.95 ft. as measured by the stream gauge near West Bridgewater, VT. Consider how deep you would theoretically need to dig the riverbed to stop a flood that high. As an example, state officials said that, in Barre City, you would need to dig down 100 feet in the Stevens Branch to reduce flood risk. The deeper you dug, the more property and homes would fall into the river as the banks continued to erode. There is also the additional consideration that, when you dig a hole in a river, it naturally wants to fill in again. So, dredging once would mean that we would be committing to regular dredging in perpetuity.

Flooding on River Street in Windsor from the 1927 flood. Citation: Digital Vermont: A Project of the Vermont Historical Society, accessed August 21, 2026, https://digitalvermont.org/Flood1927/F-FLO-1927-Windsor_RiverStreet.jpeg.

For hundreds of years, Vermont dredged and straightened its rivers. This simply concentrated the force of the water and made it more erosive and downright explosive when it did flood. And let’s not forget–it did still flood even when we dredged rivers regularly. The flood of 1927 was one of the most devastating in Vermont’s history, rivaling Irene. Predating the 1927 flood, there are other documented cases of local flood damage. The first Taftsville Bridge was washed out by a flood in 1807, and Woodstock’s Elm Street bridge was damaged by floods in 1857 and 1869.

If dredging doesn’t prevent flooding, what will? Rivers need space to move and spill out over their floodplains. Floodplains dissipate energy across the land and give rivers space to meander, which allows them to maintain their own equilibrium. Indeed, many Vermont towns have embarked on projects to reconnect rivers to their floodplains to reduce flooding. For example, the Vermont River Conservancy and Town of Brattleboro restored a floodplain at a former industrial sawmill and lumber storage site on Whestone Brook, creating a 12-acre park in downtown Brattleboro. The project keeps nearly 4 feet of water out of adjacent homes by giving floodwater a place to go.

In short, widespread dredging of rivers did not stop flooding in the past and will not stop flooding now. River systems have complicated dynamics, and there is no one-size-fits-all solution to every problem. Want to learn more? The VT Agency of Natural Resources Rivers and Roads Training Program is a great place to start. You can find “Tier One: An Introduction to River Process and Management” available for free online.