A methodological investigation was successfully conducted with the aim of constructing a combined Water Supply-Demand and Economic Model of a region, Clinton County, Pennsylvania. The structure of the water flow and economic models are first discussed separately. The economic model is an aggregated version of an existing Leontief input-output model of Clinton County. The water flow model consists of water demand sectors corresponding to sectors of the economic model, water supply sectors corresponding to the four major sources of water resource and a water supply-demand (transfer) sector consisting of the water utilities. These separate models are then related by means of water use functions which relate water usage to economic activity and water use constraints which limit economic activity in the region due to water resource scarcity. The study provided not only direct water supply-demand information for the whole region but water use and economic information concerning indirect impacts on all related sectors of the combined models. Further development and use of this methodology should be fruitful. The model provides a succinct and efficient way of presenting and using a complex, interrelated set of information. (Author)