The Challenge
Freshwater ecosystem degradation; loss of native biodiversity
Project Alignment with ResilientMass Plan Priority Actions
Aquatic biodiversity conservation; ecological restoration partnerships and projects to evaluate and improve water quality.
Climate Resilience Project Scope
The purpose of this project is to provide preliminary information on the current environmental conditions at the D.F. Riley Grist Mill Dam on the Mill River in Hatfield, MA, and collect data. The dam is in unsafe condition and the owners are under a safety order from the Office of Dam Safety. The removal of the dam would reconnect miles of accessible habitat for many fish species, including several state-listed species of greatest conservation need (SGCN) and diadromous fish with extensive freshwater and ocean migrations. Preliminary data collected using this funding includes bathymetry and sediment samples, cultural resource and Natural Heritage inquiry, topography survey, and wetland delineation.
Metrics and Results
The success of this project in terms of climate resilience would likely be measured best by the number of stream miles opened (connected) for aquatic species (newly connected habitat), and the number of species that benefit from the project (number of species that migrate upstream or downstream after removal). Although the use of these funds was limited to preliminary data collection, they may contribute to the process of dam removal in the future.
Best Practices and Lessons Learned
We have acquired detailed information about the sediment profile and wetland boundaries, as well as the project geography using bathymetry and terrestrial mapping surveys. We have initiated the cultural resources and natural heritage inquiry process. These efforts are important initial steps to inform the engineering, design, and environmental and social impacts of this project. The total estimated cost of the dam removal is around $2 million; thus, more funding and work are needed to achieve this important project that would reconnect an important tributary to the Connecticut River. Paradoxically, dam removal may pose a threat to the only self-sustaining population of Dwarf Wedgemussel, a species listed as Endangered under the federal Endangered Species Act and the Massachusetts Endangered Species Act. Future actions must therefore include protection, mitigation, and restoration measures for mussels before dam removal can be completed.
Further Action
We hope to continue data collection with hydrology & hydraulics studies and project engineering and design. We also hope to conduct more in-depth pre-removal monitoring of fish and mussel species to better understand ecosystem impacts of dam removal.