Control of nonpoint sources of pollution has traditionally been within the domain of local decision makers in recognition of the critical importance of site-specific issues. More recently attention has turned to the issue of what can and should be done at the regional or national level, while recognizing the importance of site-specific attributes. This paper describes and illustrates an approach for analysis of nonpoint pollution problems that focuses jointly at the aggregate and disaggregate levels of the problem. The approach is based on linking two tools of analysis, the microparameter distribution model and the Geographical Information Systems (GIS). Although there are significant challenges to be overcome in implementing such an approach, linkage of these two policy tools has considerable promise in dealing with site-specific issues within an aggregate framework. Furthermore, GIS is potentially an important source of data for economists to exploit, given the momentum of GIS systems throughout the nation and given the relatively disaggregate nature of the data.