During 1978-1982 the International Institute for Applied Systems Analysis (IIASA) was responsible for a research project on Environmental Quality Control and Management. The project was begun under the direction of Professor O. F. Vasiliev (from the Institute of Hydrodynamics of the Siberian Branch of the USSR Academy of Sciences) and was subsequently led by myself. This review is very much a re'fiection of that IIASA project. The major themes of the IIASA project were: (i) research into the methodological aspects of modeling river and lake sys­ tems [some of the principal results of this research appear in M. B. Beck and G. van Straten (eds. ) (1983), Uncertainty and Forecasting of Water Quality (Springer, Berlin (West)), and in K. Fedra (1983), Environmental Modeling Under Uncertainty: Monte Carlo Simulation (IIASA Research Report RR-83-28)]; (ii) case studies in the application of mathematical models to lake eutrophi­ cation control [results of which are summarized in L. Somlyody, S. Hero­ dek, and J. Fischer (eds. ) (1983), Eutrophication of Shallow Lakes: Model­ ing and Management (The Lake Balaton Case Study) (IIASA Collaborative Proceedings CP-83-S3), and in K. Fedra (1983), A Modular Approach to Comprehensive System Simulation: A Case Study of Lakes and Watersheds (in W. K. Lauenroth, G. V. Skogerboe, and M. Flug (eds. ), Analysis of Ecological Systems: State-of-the-Art in Ecological Modelling, pp. 195-204. Elsevier, Amsterdam)]; iv (iii) a policy study of operational water qua,lity management [M. B. Beck (1981), Operational Water Quality Management: Beyond Planning and Design (IIASA Executive Report ER-7)].