Running with renewal: Reflections on ecosystem impacts of the landmark Penobscot River Restoration Project
Dams have impacted ecosystems for centuries, blocking connections between inland waters and the sea; people and the river. Populations of sea-run fish once measured in millions, plummeted to fractions of their historic counts. Among the ecosystems threatened by the impact of dams is the Penobscot River, Maine’s largest watershed; an extensive system of forests and wetlands, largest freshwater input to the Gulf of Maine, and home to the largest remaining population of endangered Atlantic salmon in the US. Importantly, the Penobscot has the greatest potential for diadromous fish restoration and their concomitant ecological processes. In 2004, the Penobscot Indian Nation, a hydropower company, conservation groups, and resource agencies reached an agreement that resolved decades of conflict over fisheries and hydropower development and initiated the Penobscot River Restoration Project, a collaborative action to restore self-sustaining populations of sea-run fish through a whole-system approach. The Project, implemented by the non-profit organization, the Penobscot River Restoration Trust, has reached major milestones endeavoring strategic removal of multiple barriers while rebalancing hydropower. Acquisition and decommissioning of three large mainstem dams is complete; the two lower-most mainstem dams were removed in 2012 and 2013 and construction of a nature-like bypass channel around another upriver is underway.
Internationally recognized as a model for cooperative conservation, the completed project provides 11 species of native fishes with significantly improved access to critical habitat within nearly 1,000 miles (1609 km) of watershed. By re-establishing connectivity, the Project promises renewed ecological function, cultural interactions, and economic activities throughout the watershed and Gulf of Maine. A monitoring program, comprehensive in scale and scope, began in 2009 to provide detailed information on how Penobscot ecosystems respond to large scale river restoration using before-after methodology with focus areas in geomorphology, water quality, fish community, fish passage, fish migration and habitat use, wetlands and nutrient transfer. Presently, we have a snapshot of pre-dam removal conditions and thus an objective basis for evaluating restoration outcomes post Project implementation. Although the project has yet to cross the finish line, early results depict whole-ecosystem impacts, further emphasizing the value of multi-species restoration and comprehensive monitoring. Post-project alewife and American shad counts have increased by nearly 100 fold and endangered sturgeon species have been observed upriver habitat they have been unable to access for generations. This presentation will inform watershed managers, resource specialists, and restoration interests by sharing lessons learned from large scale restoration with ecological and community values.