Abstract: Software models are important for the evaluation and management of environmental resources. This paper presents a framework for developing a software system for water quality analysis of river ecosystems. A major component of the system is a database that permits inclusion of analytical water quality and sediment data, river geometry and sampling site characteristics, hydrologic measurements, and reference information on water quality parameters and criteria. Associated with the database is software for managing, analyzing, and representing the information in the database. An object-oriented strategy is applied to derive a model of the software system. The resulting object-oriented design is then translated into an entity-relationship model, which is in turn translated into a relational model. The formality of this translation process ensures consistency among the successive design stages. The overall development approach to system design and implementation is de-scribed, and an application for evaluating water quality conditions in the upper Godavari River is presented.