Thermal electric generating stations have a potential to alter the biotic and abiotic conditions in adjacent water bodies. A multidisciplinary team of scientists and engineers from the University of Washington has developed such a conceptual framework to guide the design of power plant aquatic monitoring programs. This framework is organized into four hierarchical levels to accommodate the quality of information in a user's possession. Algorithms within the hierarchy help the monitoring program designer identify and prioritize mechanisms likely to cause ecological change, ecosystem components that might demonstrate a response, hypotheses of impact, and an appropriate sampling design for hypothesis testing. The entire framework has been programmed for interactive computer application.