There are thousands of small dams in Massachusetts that fragment and impair nearly every stream and river throughout the state, altering fish passage, flow, sediment, and nutrient movement, and making these ecosystems less resilient to natural and anthropogenic disturbances. To date, nearly 60 dams have been removed in the state, yet only a fraction of these streams have been monitored to assess water quality, habitat, and biotic responses to dam removal. Information on the benefits of dam removal, including the watershed and long-term impacts of these changes, are critical for the public to understand expectations following dam removal and to gain support for future dam removals. We also need a better understanding of ecological changes following dam removal in order to better answer questions from local, regional, and national regulatory community that impact our ability to advance projects. Over the last three years, extensive pre-removal data has been collected on temperature, dissolved oxygen, and macroinvertebrates at 12 dam removal sites across Massachusetts through a partnership with researchers at the University of Massachusetts (UMass) and the Massachusetts Division of Ecological Restoration (MDER). These data showed that most sites had significant warming downstream of dams, highlighting the potential for extensive consequences of dams on biota, particularly coldwater fishes. However, the magnitude and extent of effects of dams are highly variable across sites and raise additional questions. Here, we propose to continue sampling these 12 sites plus 3 additional coldwater streams to quantify water quality, macroinvertebrate, and fish responses to dam removal. We will use the extensive fish database for Massachusetts and collaborate with UMass, MDER, and the Massachusetts Division of Fisheries and Wildlife (MassWildlife) to add additional sites for a broader assessment of fish responses. The results will be used to model the collective ecological benefits of dam removal statewide and will be synthesized into outreach materials highlighting these benefits to promote future dam removal toward increasing the quality and resilience of stream ecosystems.
