Erosion created canyon along Sucker Brook
By Greg Elias
The town of Williston has restored a stream whose banks eroded so dramatically that it was called “ Vermont’s Grand Canyon.”
The long-running effort along Sucker Brook, which meanders through the southern third of Williston, was finished earlier this month. All that remains is to plant vegetation to stabilize the project.
The work will keep Sucker Brook a clean and smooth-flowing stream, preventing pollution and fostering aquatic life, said Carrie Deegan, the town’s environmental planner. The hope is that the restoration project will also keep the stream from becoming clogged in the future.
“This work will prevent major input of sediment and pollutants,” she said.
The project fixed a problem that began 23 years ago. In 1984, a huge rainstorm caused Sucker Brook to jump its banks and flow into an abandoned gravel pit. The pit filled and its walls eventually collapsed.
That set off a cycle of erosion, which over the years scoured out a canyon along a roughly 800-foot-long stretch of the stream that parallels Vermont 2A. The canyon – as much as 70 feet wide and 50 feet deep – came to be referred to as Vermont’s Grand Canyon, Deegan said.
Though visually remarkable, such erosion has an ill affect on the stream’s aquatic life as well as the region’s ecosystem. An estimated 300,000 tons of sediment have moved downstream over the past two decades.
Sediment clouds streams and rivers, covering plants that feed fish and smaller invertebrates, said Colleen Hickey, education and outreach coordinator for the Lake Champlain Basin Program. Clinging to the sediment are pollutants such as phosphorus, which is a major cause of algae growth.
The water from Sucker Brook, like other area streams, ends up in Lake Champlain. So even though it is not a major waterway, keeping the stream and others like it sediment-free benefits everyone in the region, Hickey said.
“The lake is a drinking water source for nearly 200,000 people who live in the Lake Champlain basin,” she said. “We need to reduce pollution wherever we can.”
Sucker Brook originates near the Williston-Hinesburg border, not far from Lake Iroquois. It runs along Route 2A before emptying into Muddy Brook, which in turns flows into the Winooski River and eventually the lake.
YEAR OF WORK
The effort to restore Sucker Brook dates back more than a decade. For years, the town worked to secure grants, negotiate with landowners and plan the project.
The town eventually obtained about a dozen grants totaling nearly a half-million dollars. They came from several sources, including the Chittenden Solid Waste District, the Lake Champlain Basin Program, the state Department of Environmental Conservation and the federal government.
The grants paid for virtually all the restoration work, Deegan said, noting that only $22,000 in Williston tax dollars were spent.
About five years ago, junk cars were removed from the stream area and measures were taken to limit further erosion. The following year, stone weirs – small dams – were placed in the steam.
The town then hired the Williston-based engineering firm Dubois & King to design a project that would permanently stabilize the stream banks and prevent erosion. The work was divided into two phases, with the upstream half completed in 2005, Deegan said.
The effort suffered a setback in February 2006 when a storm damaged part of the previously completed work. The damage was repaired last summer, and this summer the project’s final phase was finished.
The flood- and erosion-control measures include a stone-lined step pool and a channel. Stream banks were graded to create a floodplain. Several weirs slow the downhill flow of water.
Though the stream’s problems started with a natural event, Deegan said development in Williston likely accelerated the subsequent erosion.
Over the past few decades the increasing amount of paved surface in town has led to more stormwater runoff. After it rains or snows, water rapidly rushes into streams and rivers, quickly swelling them and creating a condition where banks can collapse.
Volunteers gathered this spring to plant alders and willows designed to stabilize Sucker Brook’s new floodplain and attract wildlife. Further plantings are planned for next spring, providing one last human intervention for the stream.
Vegetation would have eventually grown by itself, “but it would have taken a really long time,” Deegan said. “We’re going to help it along.”