This Technical Guidance Note was primarily prepared as a contribution to the World Bank economic and sector work—mainstreaming environmental flow requirements into water resources investments and policy reforms jointly supported by the Environment Department and the Energy, Transport and Water Department. The technical note also forms a contribution to the Bank’s hydropower investments. The main objective of the note is to serve as a guidance document as opposed to a technical manual. It has been developed to assist World Bank staff and their clients to identify ways to better incorporate the benefits associated with environmental flow protection into hydropower dam projects.Most of the material in this note will be equally applicable to hydropower dams with either multiple objectives or a single objective, but the integration of environmental flow protection into projects with multiple objectives presents some special challenges. In addition, many issues covered in this note will be applicable to other types of water infrastructure projects.

We conduct a benefit-cost analysis of a relicensing agreement for two hydroelectric dams in Michigan. The agreement changed daily conditions from peaking to run-of-river flows. We consider three categories of costs and benefits: producer costs of adapting electricity production to the new time profile of hydroelectric output; benefits of reductions in air pollution and greenhouse gas emissions; and benefits of improved recreational fishing. The best estimates suggest that the aggregate benefits are more than twice as large as the producer costs. The conceptual and empirical methods provide a template for investigating the effects of an environmental constraint on hydroelectric dams.

A report submitted to the House Resources Committee, Subcommittee on Fisheries, Wildlife, and Oceans by the Office of Technology Assessment.

The focus of this report is technologies for fish passage around hydropower generation facilities and protection against entrainment and turbine mortality.Emphasis is given to Federal Energy Regulatory Commission (FERC)-licensed hydropower projects where fish protection is a subject of controversy and congressional interest due to the Federal Power Act (FPA) and the Electric Consumers Protection Act (ECPA). Thus institutional issues related to FERC-relicensing are also discussed. (Major points of controversy are highlighted in box 1-1.) Federal hydropower projects,especially in the Columbia River Basin, and irrigation water diversions in the Pacific Northwest and California are included to the extent that they provide information on fish passage technologies(see table 1-1). Many of the technologies discussed are applicable to other types of dams and water diversions. In fact, there are many more obstructions to fish passage that are not covered by FERC-licensing requirements, than are(approximately 76,000 dams versus 1,825 FERC-licensed facilities) (70).

The development of waterways, for hydropower and other industrial uses, has substantially altered many of the freshwater habitats of the planet and this has had considerable impact upon aquatic organisms. Industrial changes in aquatic ecosystems, including hydropower development, can restrict or delay fish migration, increase predation, affect water quantity and quality, and subject fish to direct damage and stress. This review will focus on the consequences for fish welfare and the progress towards developing the means to pass and protect fish at hydropower dams, at water withdrawal facilities, and in other engineered aquatic environments. It primarily concerns the large mainstem hydropower dams in the Columbia-Snake River Basin in the northwestern United States. Some methods for improving fish passage and protection at hydropower damsinvolve modifications and additions to engineered structures and occasionally use sensory stimuli such as light, sound, turbulence, or electric fields to influence fish distributions. Measures to improve fish survival, like spilling water at a dam to provide non-turbine passage, can cause other problems for fish, for example higher dissolved gas concentrations downstream. Reducing losses of fish in industrial environments is desirable in both the industrialized world, where many fish-related problems currently exist, and in the developing world, here lessons already learned may make future development more cost-effective and benign.

The flow regime of the gravel-bedded river North Tyne has been regulated by the Kielder reservoir for the past 12 years; for the past nine years, regulation has been dominated by hydropower generation. Diurnal stage fluctuations of up to 0.6m are experienced during periods of peak hydropower flows. The main morphological and sedimentological impacts of this regulation are identified and physical explanations provided for the observed adjustments. The main morphological adjustments are identified as the degradation of riffle spawning grounds, the development of fine ssediment berms along channel margins, the aggradation of pools, vegetation of former gravel shoals and the growth of tributary confluence bars. Sedimentological adjustments are subtle and are characterized by higher percentages of fines within spawning gravels, coarsening of surface gravels and the development of a stable, strong bed fabric. The physical explanations for these adjustments relate to changes in the sediment transport regime controlled by the hydraulics associated with the pool-riffle swquence during hydropower generation

In this article, I describe the importance of large river-floodplain ecosystems and some of the consequences of altering their natural processes, functions, and connectivity. Then I contrast the species-focused management typically employed by natural rescue agencies with the ecosystem approach. I define ecosystem management as working with the natural driving forces and variability in these ecosystems with the goal of maintaining or recovering biological integrity. I focus on flood pulses both because they drive these systems and because the great floods of 1993-1994 in Asia, Europe, and North America heightened public awareness, thereby creating an opportunity to change river management policies.
I draw my examples largely from the upper Mississippi River and Illinois River because I am most familiar with them. They also exemplify both the conflicts between development and conservation of large floodplain rivers that have occurred world wide and the more recent restoration and rehabilitation efforts that are beginning in Europe and the United States.
The Mississippi River and Illinois River comprise the Upper Mississippi River System, which the US congress designated as both a "nationally significant ecosystem" as well as a "nationally significant waterway" in the Water Resources Development Act of 1986.Plans for even greater expansion of navigation capacity are currently being developed by the US Army Corps of Engineers. But federal and state natural resource agencies and several environmental groups fear that the integrity of the upper Mississippi is being compromised. They have issued their own strategies and plans for conserving and restoring the river.

Scientists at the Mid-Continent Ecological Science Center of the National Biological Service conducted a series of case studies of Federal Energy Regulatory Commission license consultations. The goal of these studies was to test hypotheses abbot factors that contribute to success in interagency negotiations. Based on their analysis of six case studies, the researchers constructed a list of ten "rules for success." Examples include: Analyze the incentives of each party to negotiate, paying special attention to parties who gain by not negotiating; Clarify the technical issues so that all agree and they coincide with resource management objectives; and make sure the final agreement is feasible form both a physical and a policy perspective so that it can actually be implemented. These rules can be used to plan for negotiations and to diagnose ongoing negotiations.

Responses of rivers and river ecosystems to dams are complex and varied, as they depend on local sediment supplies, geomorphic constraints, climate, dam structure and operation, and key attributes of the biota. Therefore, "one-size-fits-all" prescriptions cannot substitute for local knowledge in developing prescriptions for dam structure and operation to protect local biodiversity. One general principle is self-evident: that biodiversity is best protected in rivers where physical regimes are the most natural. A sufficiently natural regime of flow variation is particularly crucial for river biota and food webs. We review our research and that of others to illustrate the ecological importance of alternating periods of low and high flow, of periodic bed scour, and of floodplain inundation and dewatering. These fluctuations regulate both the life cycles of river biota and species interactions in the food webs that sustain them. Even if the focus of biodiversity conservation efforts is on a target species rather tan whole ecosystems, a food web perspective is necessary, because populations of any species depend critically on how their resources, prey, and potential predators also respond to environmental change. In regulated rivers, managers must determine how the frequency, magnitude, and timing of hydrologic events interact to constrain or support species and food webs. Simple ecological modeling, tailored to local systems, may provide a framework and some insight into explaining ecosystem response to dams and should give direction to mitigation efforts.

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.

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.