An environmental decision support system (EDSS) was designed for the Occoquan system in Northern Virginia, USA. This EDSS is available through the internet using web-browsers, and enables stakeholders to interact with complexly-linked water resources models for the Occoquan system based on seven implementations of HSPF and two implementations of CE-QUAL-W2 software. Using the web-interface of the EDSS, users may delineate land use changes and simulate the water quality impact of such changes by remotely executing the water resources models. The EDSS utilizes a server cluster to share the computational load of simultaneously executing multiple instances of the linked Occoquan system models along with methods to limit ‘similar’ model executions. The server cluster was assembled from disparate machines with spare computing resource available on the local network, thereby eliminating the need for any additional hardware to execute an increased number of model simulations. It is expected that the enhanced accessibility to the water resources models through the EDSS may allow stakeholders to use the models as a planning and educational resource, without direct expert modeler's involvement. Further, this EDSS is comprised of modules that may be extended to other watersheds with similar legacy, calibrated modeling systems.