Policy, regulatory and conservation bodies in the UK have identified an urgent need for a pragmatic decision support system that will allow measures to control agricultural loads of particulates and phosphorus (P) to be implemented in a strategic way within priority river basins suffering the effects of diffuse pollution. Using current scientific understanding and available information, together with a cost-conscious water qual- ity monitoring and sampling programme, research is underway to develop a decision support system to locate specific source areas of particulate and P loss in two study basins, identify practical and cost-effective options to control the loss in these areas, and evaluate the nature and scale of any barriers to uptake. In addition, the project seeks to identify the data requirements and costs needed to operate such a decision support system, the scale at which the data is required together with the ease and cost of accessing the data. A two-stage approach has been adopted which includes an initial identification of high-risk areas in each basin using risk assessment methodology and 1 km2 datasets, followed by a finer scale (field/farm) assessment of specific source areas of particulate and P loss within the high risk areas, and their export rates. Cost- effective control practices will be informed by process-based modelling approaches which are able to quantify the impact of changes in P inputs and land management on P export rates. The experiences, drawbacks and challenges of developing such a decision support system are described in the context of the requirements of the EC Water Framework Directive.