Hydro is at risk of being regarded as an 'unsustainable renewable' resource unless something is done to change significantly the existing, sometimes controversial, process of planning and siting projects. Hydro developers and funding/regulatory agencies should shift their focus from 'the project' to long-term hydro planning at river basin level. Engineers could make better decisions on which sites to investigate within river basins by collaborating with NGOs and other water resources stakeholders before proceeding with projects.
The substantial size of some hydroelectric projects and the extensive total surface area convered by reservoirs globally require that research determining the impacts of these developments be done at ever-increasing spatial and temporal scales. As a consequence of this research, new views are emerging about the spatial extent and longevity of the environmental and social impacts of such developments. New findings challenge the notion of hydroelectric development as a benign alternative to other forms of power generation. This review examines the intertwined environmental and social effects of methylmercury bioaccumulation I th efood web, emission of greenhouse gases from reservoirs, downstream effects of altered flows, and impacts on biodiversity, each of which operates at its own unique spatial and temporal scales. Methylmercury bioaccumulation occurs at the smallest spatial and temporal scales of the four impacts reviewed, whereas downstream effects usally occur at the largest scales. Greenhouse gas emissions, the newest surprise connected with large-scale hydroelectric development, are relatively short term but eventually may have important global-scale consequences. Limitation of biodiversity by hudroelectric development usually occurs at intermediate spatial and temporal scales. Knowledge developed from working at expanded spatial and temporal scales should be an important part of furure decision making for large-scale hydroelectric development.
This article presents and overview of the hydropower industry and summarizes two recent events that have greatly influenced relicensing and environmental issues. First, the US Supreme Court's May 1994 Tacoma decision raised fundamental questions about who has the authority to relicense hydroelectric power plants. Second, under the Endangered Species Act, Federal agencies are required to ensure that their actions do not jeopardize protected species and their habitat. The impact of the Act has been particularly significant recently for the federally owned facilities in the Pacific Northwest that are presently under streamflow restrictions aimed at aiding endangered local fish populations.
There is a highly polarized environment in which decisions balancing protection of fish populations and energy generation are made. Hydroelectric power accounts for 12% of U.S. electric supply and virtually all the nation's renewable enrage capacity. Yet, hydro is under increasing attack on environmental grounds, mostly for inputs on fish populations. The 1992 listing of sockeye salmon as endangered has intensified a long-running battle over restoring fish runs and sent mitigation costs skyrocketing. Further complicating the regulatory picture, a Supreme Court decision this spring appears to allow states to set minimum flows at hydroelectric facilities under the authority of the Clean Water Act. The real challenge for applied ecologists will continue to be: how best to put the right information on the table, in the right form, and at the right time to best incorporate ecological consequences in the decision making process.
American Rivers produced abstract