The EU Water Framework Directive and ist Groundwater Daughter Directive call for a cost-effective protection of all water resources. For groundwater, the assessment of cost-effective protection measures is complicated by the long time lags and the flow dynamics within aquifers. Together with the water supply company OOWV and the Lower Saxony Board of Agriculture, Ecologic has analysed the cost-effectiveness of groundwater protection measures in a drinking water protection area, and thereby developed a practical solution for dealing with the specific problems of cost-effectiveness analyses related to groundwater.

The cost-effectiveness analysis was carried out in the frame of the Interreg project WaterCost. This project aims to develop a practicable methodology for cost-effectiveness analyses of groundwater protection measures, and to test this methodology in five European regions. To this end, the project brings together partners from different European countries, including municipalities, water supply companies and environment agencies. Ecologic supports the German partners in this project, the water supply company for Oldenburg and Easter Frisia (OOWV) and the Chamber of Agriculture for Lower Saxony.

The study region, the Thülsfelde groundwater protection area, covers 8,000 ha which are mostly used for agricultural purposes (maize and cereal production). The cost-effecitveness analysis compares a number of measures for reducing nitrate loads from agriculture, ranging from improved nutrient management to land use changes (afforestation and extensive grassland). To this end, three scenarios are compared in terms of their costs and their overall effectiveness. In the process, the analysis was partly based on a manual developed in the UK on behalf of the Department of the Environment, Food and Rural Affairs (DEFRA).

Benjamin Görlach presented some preliminary results at a Workshop in Oldenburg on 26 April 2007.