The aim of the project was to help to provide Water Framework Directive "competent authorities" with cost-effective and sustainable measures for the management of groundwater quality, in the context of river basin management plans. The WaterCost project aimed to provide guidance on how to obtain an integrated and environmentally sustainable approach to groundwater protection and management. In overall, the project aimed to help to deliver cleaner groundwater in regions around the North Sea and protection of the groundwater from future pollution - preventing the groundwater from becoming polluted in the first place. Achievements: The main achievement of the WaterCost project was the delivered framework for cost-effectiveness analysis (CEA) and the framework to assess the cost effectiveness and include wider impacts for various measures for groundwater protection. Furthermore, the WaterCost handbook presents four case studies showing in particular how CEA have been applied in partner regions, identified strength and weaknesses with the methods. The specific aim has been to assess the cost effectiveness of measures to reduce the nitrate concentration in groundwater. This has been achieved through the pilot activities and the learning has been passed on through the booklet.The results of the project, represented by the booklet WaterCost: Elements of Cost-Effectiveness Analysis method and case studies have been presented to DG Environment and provided valuable input for the drafting guidelines for Member States on Land Use and Groundwater developed during spring 2008 by the Commission.