BASINS is a comprehensive watershed assessment tool designed to integrate analysis of point and nonpoint sources. It brings together environmental data, state-of-the-art assessment and modeling tools, and ArcView to tackle complex watershed/water quality management issues. Recent enhancements to BASINS include integration of the Soil and Water Assessment Tool (SWAT), integration of ArcView Spatial Analyst, and modeling on EPA's Reach File 3. To extend the capabilities of BASINS, a next generation modeling toolkit is under development to support advanced modeling applications. This toolkit is designed around a client-server architecture that emphasizes the seamless integration, sharing and reuse of data to support modeling activities. This paper demonstrates (1) innovative techniques to examine environmental information, (2) an integrated watershed modeling framework, (3) analysis of point and nonpoint source management alternatives, and (4) the application of a more robust software architecture to support all aspects of modeling analyses.