On Wednesday, August 30th, 35 dam removal and stream restoration practitioners, as well as members of the public, visited a project site in Bakersfield, VT to learn lessons from the removal of the Johnsons Mill Dam.
The Johnsons Mill Dam was built on the Bogue Branch in the Tyler Branch subwatershed of the Missisquoi Bay Basin. Thought to have been built in 1922 at the same location as a previous dam built originally between 1819-1827, the Johnsons Mill Dam served a sawmill on the property on Witchcat Road that was in use until 1971. Effectively 150 years of sediment, logs, and debris had accumulated upstream of the dam along the Bogue Branch, influencing the water and soil dynamics along the stream, both upstream of the dam where sediment had accumulated, and downstream, where the stream was sediment-starved.
In August 2021, the dam was removed by engineers, project managers, archaeologists, historians, ecologists, and contractors. The dam had previously partially breached in the 2019 Halloween storm which sent an uncontrolled amount of sediment and concrete downstream. In 2021, following design plans and permits, the dam was removed along with hundreds of cubic yards of sediment that had accumulated upstream.
In August 2023, the project team and interested community members visited the dam removal site to observe changes in the stream and floodplains and to share ideas about how things could be done differently in the future at other dam removal sites in the Lake Champlain Basin and across Vermont.
The Franklin County Natural Resources Conservation District, in partnership with Stone Environmental, Avacal Biological Consulting, and Whiteout Solutions, have been working on a monitoring project at the site capturing changes in physical and biological features since the dam was removed and will continue this intensive monitoring through 2025. We will share out final findings following completion of the project.
Some of the things we are monitoring for 4 years post-removal include:
streambed material characterization
pebble counts
bed material under surficial armor layer characterization
topographic and bathymetric surveying
wood recruitment
plant survival and coverage
imagery analysis
field work and visual observation
seasonal aerial imagery
algal analysis
macroinvertebrate analysis
e-fishing surveys
time lapse photos at different angles of the site
Some things we didn't include but might recommend in the future:
Temperature logging over time
pH
Invasive plant establishment
Some of the lessons learned so far that were discussed at the event include:
ensuring projects like this have pre-implementation baseline data and post-implementation data collected for metrics to show the impacts of the projects from before to after the implementation so that we can measure the impacts; monitoring plans should consider how dramatically a site may change physically and plan to be adaptable
using game cameras to capture time lapse photos of the site over time is a great way to definitively know what is happening at the site and when
staff at on-the-ground organizations can lead big projects like this, but funds to improve staff retention and allow for community outreach and engagement are critical to the long term success of these projects
dam removals are large, disruptive events to ecosystems that require patience and trust in nature's processes to seek dynamic equilibrium and create healthy streams
construction/implementation often cannot follow engineering plans exactly so flexibility is important during the implementation phase and after
it is important to take your time during removal to allow sediment to move through the system to determine the extent of dam removal needed in the channel bed
funding for projects like these is often piecemeal and difficult to find, funding sources should be more flexible to different arrangements of design and implementation, as well as willing to fund changes to the budget as they occur and things are discovered
dam removals take a large team across organizations and businesses to accomplish well
and many more!
We are excited to keep learning from this landscape over time to see changes in the physical and biological characteristics of the removal site, as well as upstream and downstream. We are all connected through our waterways and it's an exciting opportunity to watch a system heal itself. Thanks to all who attended and have expressed interest in the project.
To learn more, please explore these sites:
This project has been funded wholly or in part by the United States Environmental Protection Agency under assistance agreement (LC00A00707-0) to NEIWPCC in partnership with the Lake Champlain Basin Program (LCBP). NEIWPCC manages LCBP's personnel, contract, grant, and budget tasks and provides input on the program's activities through a partnership with the LCBP. The contents of this document do not necessarily reflect the views and policies of NEIWPCC, the LCBP, or the EPA, nor does NEIWPCC, the LCBP, or the EPA endorse trades names or recommend the use of commercial products mentioned in this document.