This paper, using Ireland as a case study, examines the relationship between economic activities and river water quality. The stipulation from the EU water framework directive (WFD) that all surface waters in the EU must be of ‘good ecological status’ by 2015 necessitate a quantitative understanding of the major determinants of water quality. Within this context, this paper combines a number of spatial datasets relating to agricultural, residential and industrial activities as well as the level of forest cover to examine the major economic influences on the ecological quality of water resources. It is hoped that providing a comprehensive understanding of the effect of a variety of economic activities that influence the ecological quality of water will be an important tool in the management of risk and will allow for more appropriate land use planning aimed at restoring and maintaining water quality as required by the WFD. Results indicate that the level of forestry, industrial activity, the intensity and type of agricultural activity and the type of wastewater treatment in an area are all critical factors affecting the quality of our water resources. Moreover, the results highlight the importance of a spatial dimension to any analysis as the principal factors affecting water quality often differ across river catchments.