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News Learning from the Eel River Headwaters Project

DER is taking steps to encourage learning and improve our practice of freshwater wetland restoration.
  • Division of Ecological Restoration
Six images showing the changes in Eel River before and after restoration

DER strives to incorporate learning into all of our work. The practice of ecological restoration is still relatively new, as is the science of restoration ecology. Both practitioners and scientists have much to learn from each other and from project outcomes. What works, what could be improved, and what should be avoided? In the rush to complete the next project, we can sometimes overlook the importance of slowing down to learn. DER is taking steps to encourage learning and improve our practice of freshwater wetland restoration.

The Eel River Headwaters Restoration Project is well-known to Ebb&Flow readers. Completed in 2010, it was the first of its kind - a comprehensive ecological restoration of retired cranberry farmland. The project was led by the Town of Plymouth, and supported by DER, the U.S. Fish and Wildlife Service, USDA’s Natural Resources Conservation Service (NRCS), The Nature Conservancy (TNC), and others. The project was engineered by Inter-Fluve, Inc. and constructed by SumCo Eco-Contracting. The work involved channel reconstruction, dam removals, culvert replacements, grading, and extensive plantings across a 60-acre site. The techniques pioneered at Eel River have since been used at Tidmarsh Farms (Plymouth), and will soon be used elsewhere, including the Coonamessett River (Falmouth) and Cold Brook Preserve (Harwich).   

To help generate insights that can be applied on other projects, and to complement more formal monitoring activities, DER organized a site walk with project partners at Eel River this past summer. Area by area, the group reviewed restoration treatments, examined before and after maps, and then set out across the site to collect observations. What we found was surprising and inspiring. We knew that the site was on a healing trajectory; monitoring activities over the past several years were already telling us that. But by getting in the muck together, we uncovered new wonders, and clear changes from just a few years back. For example:

  • A new layer of sphagnum moss is now present on top of the former sand layer of the old farm. We measured 4 inches of sphagnum in many locations! This is an impressive recovery of a cornerstone bog species in just a few years.
  • The spread of moss seems to be driving other changes. For example, we observed hundreds if not thousands of new Atlantic white cedar (AWC) seedlings. Perhaps the moss is just the right landing surface for AWC seeds? Perhaps it is now at the right density for AWC germination?
  • Many of the AWC planted in 2010 are now over 12 feet tall. Much of the site has the appearance of a young AWC swamp.
  • In some places, the reconstructed channel is full of plants. This may lead to elevated water temperatures and reduced dissolved oxygen levels. We will use this observation to re-consider the geometry of restored channels, especially where coldwater fish are present.

All of these findings confirm that ecological restoration takes time. If done properly, restoration interventions like dam removals and ditch plugging simply re-establish and jumpstart the appropriate natural conditions and processes that are needed for healing to take place. The real restoration “work” is done by nature over time. At Eel River, nature’s healing work appears to be well underway.

DER is developing a structured learning agenda around key issues associated with wetland restoration at retired cranberry farmland. Stay tuned in the years ahead as we collectively learn much more about the effects of wetland restoration on water quality (e.g., nitrogen removal), soil moisture and plant response, fish and wildlife, and greenhouse gas dynamics.

Division of Ecological Restoration 

DER restores and protects rivers, wetlands, and watersheds in Massachusetts for the benefit of people and the environment.