As understanding increases, data requirements will change and an iterative conceptual modelling approach will allow this to be clarified. Although the project is led nationally by policy makers (Department for Environment Food and Rural Affairs - Defra - and the Environment Agency), it will encompass the interests of all other relevant sectors in a collaborative approach, including the farming community, water companies, environmental non-governmental organisations, and the research community. The development of communities of practice, which develop approaches to fit their discrete geographical and local circumstances, but are also able to learn from each other and serve as examples to communities in other catchments, is an overarching goal of the DTC programme.