A River on the Move

Looking downstream from Lareau Swimhole provides a good example of how the Mad River naturally bends, depositing sediment on the inside of the bend. Photo: Donna Van Halle

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By Ira Shadis, Executive Director

On June 22nd & 23rd, teams of Mad River Watch volunteers visited their field sites to collect important data and make careful environmental observations for the second time this summer. This article is part of an ongoing series that shares highlights from this field work as well as lessons learned from this year and the past 40 years of Friends of the Mad River’s Mad River Watch program.

A history of channel management

“Rivers are dynamic systems,” says Friends of the Mad River Director Ira Shadis. “Over the course of their life, they will change in some pretty extreme ways. When glaciers started retreating from the valley 14,000 years ago, water flowed through the Granville gulch and joined up with the Connecticut River basin. We might not have glaciers today, but the more recent history of human activity has definitely impacted the way water moves through this landscape.” 

Assessments of river dynamics were completed in 2008 for the upper Mad River and in 2018 for the portion of the river that flows through Moretown. The 2008 report noted that, “with the exception of three reaches found in narrow, bedrock-controlled settings, the Mad River has been historically altered, and in many areas, ‘locked in place’ through channel straightening and dredging, application of bank armoring, and removal of stream bank vegetation.” The cumulative effect of these activities has been a simplified channel form (i.e. a river with fewer bends and less vegetation) that provides only limited habitat for aquatic wildlife.

“The historical assessment of the floodplain, through aerial photographs and other maps, suggests that major channel management projects were undertaken following the 1927 and 1938 floods,” says Shadis. “These were substantial undertakings whose effect we are still feeling today. And, while these projects might have provided some short-term protection to a few properties along the river, we know that when a river is hardened in this way it will send flooding and erosion issues to the next property downstream.”

A Catalyst for Change

At a recent flood resiliency event hosted by Friends of the Mad River and the Mad River Planning District, panelists reflected on the lessons learned from the 2023 and 2024 July floods. Dan Fingas, Plainfield Selectboard member explained that “anytime you try to engineer an end result with the river, it’s going to have a downstream or an upstream effect. You might fix [the issue] for your town but you’re not going to fix it for the towns around you.” As major storms roll through the region, they can have a direct impact on the evolution of the river. Increased flows accelerate normal processes and can rework sections of the river overnight. 

Some stretches of the Mad River are more prone to erosion and others are more prone to deposition of material. “The slope of the river, historic disconnection from the floodplain, the presence or absence of woody material in the channel, and health of riparian buffers can all play a role in determining which areas lose, transport, and accumulate material,” says Shadis. “At the end of the day, the river is trying to regain equilibrium within the physical (and biological) boundaries of the surrounding land. The more room we can give the river, the more opportunity there is for an ecologically rich and biodiverse community to take advantage of that equilibrium. For us humans, the challenge of living along the river arises from the fact that we also want a sense of equilibrium when it comes to our roads, houses, and other infrastructure – and that sometimes the river disagrees with us.”

Notes from the Field
Heavy rains on Saturday night and early Sunday morning showed up in volunteer observations. At Warren Covered Bridge, a tree broke and leaned into the river (providing critical shade to protect brook trout during this week’s heatwave). Volunteers noted similar evidence of erosion and deposition at nearly all field sites. Of note from the first set of field days, significant washouts along Brook Road in Waitsfield showed up as increased turbidity in High Bridge Brook. Water Temperatures ranged from a low of 56F at 10am Sunday at Warren Falls to a high of 69F at 1pm Sunday at Hopper Lane in Moretown.