From executive summary: Many guidance documents are available for conducting impact assessments at power plants, but none adequately address the problems of study design, implementation, and evaluation, particularly as they relate to assessing impacts on fish and shellfish populations. This lack of guidance frequently results in the acquisition of irrelevant or extraneous information. Since the regulatory and coordinating agencies (such as the U.S. Fish and Wildlife Service) must review and evaluate power plant impact assessments, a strategy has been developed which, if implemented, will enhance the collection of relevant data and the reliability of conclusions related to predicted or measured impacts. The strategy was designed for use by biologists responsible for conducting or reviewing assessments of impacts on fish and shellfish. Rather than a 'cookbook' recipe for performing an 'ideal' impact assessment, this is a generic strategy that promotes consistency and uniformity in the design and performance of aquatic ecological impact assessments. The result of following this strategy should be the collection of information amenable to utility company and regulatory decision-making procedures.