Too often advocates for river restoration through dam removal find themselves in the middle of a project and at odds with potential partners over matters of historic preservation. The goal of Dam Removal and Historic Preservation: Reconciling Dual Objectives is to help dam removal proponents and advocates for historic preservation work together more effectively to achieve their mutual goals, while building constructive relationships and successfully reconciling potentially competing objectives. This report combines a primer on Section 106 of the National Historic Preservation Act with methods for avoiding, minimizing, or mitigating the adverse effects of a dam removal project and concludes with real life case studies.

Available online at http://www.americanrivers.org/site/DocServer/Dam_Removal_and_Historic_Preservation.pdf?docID=8161 

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 number of salmon migrating up US rivers has declined significantly in recent years, bringing hydro plants under increased scrutiny. Indeed, fish protection has become the biggest issue in hydro plant relicensing, and utilities across the country are under pressure to step up their fish protection efforts. Currently, much of the regulatory emphasis is focused on downstream passage technologies. EPRI's laboratory and field tests have identified the most promising of these technologies. However, the effectiveness of each approach varies according to the site and the fish species and life stage.

Utility companies release water to mitigate the effects of hydroelectric projects on fish habitats. Utility companies, government agencies, and research communities in Canada, the United States, Europe, New Zealand, and Australia were surveyed as part of a Canadian Electrical Association study to evaluate the effectiveness of water release as a mitigation. Respondents identified only 28 projects in which water was released specifically to protect fish habitats. Fewer than half of these projects (12) were judged as being effective. Six case histories with preimpact assessment and postimpact monitoring were reviewed. In four cases fish habitat or fish populations or both were maintained; in two cases they were not. The effectiveness of water release differed among rivers and fish species, and was greatest when designed to meet the habitat requirements of each life-history stage. A review of the literature did not support the theory that a particular fraction of the mean annual flow provides the best fish habitat. Although smaller changes in the flow regime had smaller effects, increasing minimum flows above those historically observed did not necessarily increase fish production.