Abstract
Although hydropower is a source of low-carbon energy, without careful consideration and management, dams have the potential to degrade river ecosystems and the goods and services they provide to society. Today, a broad range of hydropower interests and stakeholders are seeking approaches to hydropower development and operation that are more environmentally and socially sustainable. The Penobscot River Restoration Project ('the Project') illustrates that basin-scale approaches can provide a broader set of solutions for balancing energy and riverine environmental resources than can be achieved at the scale of individual projects. The Penobscot basin is the largest in Maine and historically supported culturally and economically significant populations of migratory fish. These migratory fish populations declined dramatically following the construction of a series of hydropower dams on the main stem river and major tributaries in the early 20th century. The Project, negotiated between a power company (PPL Corporation) and a coalition including the Penobscot Indian Nation, resource agencies, and nongovernmental conservation organizations, features the removal of two main stem dams on the lower Penobscot and improved fish passage at the dams that remain. Because of various capacity and/or operational changes, power production will be increased at the remaining dams and total hydropower energy production from the basin will be maintained or increase slightly. The Project is expected to expand considerably the proportion of the basin accessible to migratory fish and contribute to significant increases in fish populations. The Project illustrates that a basin-scale approach can potentially yield more comprehensive solutions for sustainable hydropower than can be achieved at the project scale, and we recommend that such large-scale planning processes can improve the sustainability of both regulatory licensing of existing dams as well as the planning of future dams in regions undergoing the expansion of water-management infrastructure.
Highlights
Hydropower poses one of today’s more complex environmental challenges: hydropower dams generally produce low-carbon energy they can disrupt river ecosystems and diminish or eliminate the numerous important societal and ecological benefits provided by free-flowing, healthy rivers (Postel and Richter 2003)
Hydropower is a source of low-carbon energy, without careful consideration and management, dams have the potential to degrade river ecosystems and the goods and services they provide to society
The Penobscot basin is the largest in Maine and historically supported culturally and economically significant populations of migratory fish. These migratory fish populations declined dramatically following the construction of a series of hydropower dams on the main stem river and major tributaries in the early 20th century
Summary
Hydropower poses one of today’s more complex environmental challenges: hydropower dams generally produce low-carbon energy they can disrupt river ecosystems and diminish or eliminate the numerous important societal and ecological benefits provided by free-flowing, healthy rivers (Postel and Richter 2003). Starting in the 1820s, dams were constructed on the Penobscot main stem just above head of tide and in the current locations of the Veazie, Great Works, and Milford dams (Fig. 1, Table 2), blocking passage to migratory fish spawning and rearing grounds These impacts were apparent the first year after the closure of Veazie dam as “a great many shad and alewives lingered about the dam and died there, until the air was loaded with the stench” (Atkins and Foster 1869). Most toxic inputs to the river ecosystem, e.g., dioxin, mercury, DDT, and chlorine compounds, have declined over the past 40 years since the adoption of the federal Clean Water Act. Despite water quality improvements, current stocks of most migratory fish on the Penobscot are at or near historic lows and commercial fisheries have long since shut down (Saunders et al 2006, Maine Department of Marine Resources 2009).
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