I. Introduction As many case studies have shown, co-operative agreements (CA) can be more effective than other instruments, such as compulsory rules and taxes. Furthermore, the costs of achieving water-related objectives are relatively low. The presentation aims to illustrate this by cases where voluntary agreements between farmers, water suppliers and authorities have been successfully established in groundwater catchments areas. Case 1: Catchment “Holsterhausen/Üfter Mark”, North Rhine Westphalia, Germany Water Supplier: RWW, Mülheim an der Ruhr Total water delivery: 84 Mio. m³ per year Drinking water supply: about 1 Mio people Groundwater abstraction Holsterh./Üfter Mark: 25 Mio. m³ per year Farmland concerned: 10,000 ha with 320 farmers and 32 gardeners Population concerned: about 350,000 people Agricultural products: Maize, corn, grass, pig fattening, dairy cattle References 1.Heinz I. et al. (2002): Co-operative agreements in agriculture as an instrument to improve the economic and ecological efficiency of the European Union water Policy. Research project funded by the EU Commission: ENV4-CT Brouwer F., I. Heinz and T. Zabel (2003): Governance of Water-related Conflicts in Agriculture. New Directions in Agri-environmental and Water Policies in the EU. Kluwer Academic Publishers. 3. Heinz I. (2004): Sustainable farming as a result of negotiations: an analysis at EU level CIGR International Conference, Beijing, China, October Cost-effective Measures to Protect Groundwater by Co-operative Agreements Ingo Heinz Institute of Environmental Research (INFU), University of Dortmund, Otto-Hahn-Str.6, Dortmund, Germany, Phone: , Fax: , Conclusions and perspective Aim of the agreement (established in 2002): Water company Paying advisory services Compensation payments for changes of farming practice Financial supports for purchase of water-protective equipments Monitoring of soil (e.g. nitrate min ) and water Assessing nutrient balances and plot card-indexes To prevent further increase of nitrate and pesticides concentration (preventative case) without putting farmers at an economic disadvantage Contents of the agreement: Farmers Intercropping (e.g. green rye) and under seeding More efficient application of fertilisers (by using e.g. drag hoses) Retention period for semi-liquid manure (from 15 September to 15 January) Spreading of semi-liquid manure on alternative crops other than maize Extended storage facilities for semi-liquid manure Nutrient balancing and plot card-indexes Mechanical weed control Application of pesticides better adapted to the actual needs (e.g. modern sprayers) Use of beneficial insects instead of pesticides Impacts of the agreement on water quality Average nitrate concentration (mg/l) Economic impacts of the agreement Expenditures of the water company: 420,000 Euro per year Increased cost in water supply: Euro / m³ Proportion to water price: 0.9 % (of around 1.80 Euro) Prevented treatment cost (hypothetical):1.5 – 6.0 Mio Euro per year Case 2: Catchment “Viersen (Süchteln)”, North Rhine Westphalia, Germany Water Supplier: NiederrheinWasser GmbH, Teil: Niederrheinwerke Viersen Total water delivery: 5.5 Mio. m³ per year Drinking water supply: about people Groundwater abstraction “Viersen (Süchteln)” 860 m³ per year Farmland concerned: 570 ha with 35 farmers Population concerned: about people Agricultural products: Maize, cereals, grass, pig fattening, dairy cattle Aim of the agreement (established in 2001 Reduction of nitrate and pesticides concentrations (remedial case) without putting farmers at an economic disadvantage Contents of the agreement : Farmers and water company Similar to Case 1 with some different commitments (e.g. retention period for semi-liquid manure from 1 September to 15 February) Impacts of the agreement on water quality Economic impacts of the agreement Average nitrate concentration (mg/l) Expenditures of the water company for all 4 catchments: Increased cost in water supply: Proportion to water price: Prevented treatment cost: 395,000 Euro per year (2005) 0.07 Euro / m³ (2005) 3.5 % (of around 1.50 Euro) 648,000 – 972,000 Euro per year 1.Voluntary agreements help to prevent pollution (precautionary principle) 2.By such agreements pollution can be reduced cost-effectively 3. Farmers and water companies are exchanging their expertise 4.The changes of farming practice are targeted at the site-specific requirements 5.Agreements help to implement the WFD and CAP reform, especially the Groundwater Directive, due to their cost-effectiveness and site-specific flexibility.