This report is part of a continuing study of the design and analysis of aquatic environmental monitoring programs for assessing the impacts caused by nuclear power plants. The efforts of this year's study were divided into ecological monitoring, simulation model evaluation and hydrologic modeling. Analysis of ecological monitoring data from three nuclear power plants confirmed the generic applicability of a control-treatment pairing (CTP) design suggested by McKenzie et al. (1977). Simulation models of aquatic ecosystems were reviwed and evaluated. A process notebook was compiled and each model equation was translated into a standarized notation. Individual model testing and evaluation was started. The Aquatic Generalized Environmental Impact Simulator (AGEIS) was also developed at the University of Washington. A compendium of models commonly applied to nuclear power plants was assembled and two well-received hydrodynamic models were applied to data from the Surry Nuclear Power Plant. Conclusions indicated that slight inaccuracies of boundary data have little effect on masss conservation, but for model calculations, accurate bathymetry data are necessary fr conservation of mass. The results of this year's work should provide valuable reference information for model users and monitoring program designers.