Researchers at Virginia Tech have put together the primary structure of a web enabled integrated modeling system that has potential to be a planning tool to help decision makers and stakeholders in making appropriate watershed management decisions. This paper describes the integrated system, including data sources, collection, analysis methods, system software and design, and issues of integrating the various component models. The integrated system has three modeling components, namely hydrology, economics, and fish health, and is accompanied by descriptive 'help files.' Since all three components have a related spatial aspect, GIS technology provides the integration platform. When completed, a user will access the integrated system over the web to choose pre-selected land development patterns to create a 'what if' scenario using an easy-to-follow interface. The hydrologic model simulates effects of the scenario on annual runoff volume, flood peaks of various return periods, and ground water recharge. The economics model evaluates tax revenue and fiscal costs as a result of a new land development scenario. The fish health model evaluates effects of new land uses in zones of influence to the health of fish populations in those areas. Copyright ASCE 2004.