b'Science tools to help get the right measure in the right placeMockler E1 and Deakin J11Catchment Science and Management Unit, Environmental Protection Agency, Dublin, IrelandCatchments characterisation involves understanding how catchments work from the mountains to the sea. This includes assessing the impacts and risks of human activities on the water environment to help prioritise and target key pressures and highest-risk geographical areas for further investigation and inclusion in a programme of measures. A key change in catchmentscience and management in recent years has been the move from national, one size fits allmeasures to more localised action and the right measure in the right place. The EPA carried out a national characterisation assessment of water bodies for the second cycle of the Water Framework Directive (WFD) which included evaluation of physical, hydrochemical and ecological characteristics, and a risk assessment of pressures, pathways and impacts.Diffuse sources of pollution are a major challenge and understanding the source- pathway-receptor linkages and the critical source areas (CSAs) is important for targetingmeasures. The assessments used results from water quality models including the national PIP-P (Pollutant Impact Potential for Phosphorus) map, the SANICOSE model for septic tanks systems and the SLAM (Source Load Apportionment Model), and an assessment of risk of water bodies not achieving their WFD objectives, to identify areas where local catchment assessments could be targeted for maximum positive impact. This is being further developed through theDiffuseTools Project to greatly improve the mapping of CSAs and the ability to pick out the areas of farms where buffers will be most effective.The characterisation assessments support a collaborative nine step prioritisation process used to identify Priority Areas for Action. The Local Authority Waters Programme (LAWPRO) areworking in these Priority Areas for Action to refine the understanding of the pressures andimpacts at the local scale, and to work with others to get the right measure in the right place implemented. Where agriculture is a significant pressure, the Agricultural Sustainability Support and Advice Programme (ASSAP) provide farmers with a free and confidential advisory service to help improve water quality.30'