Diffuse nutrient impact on surface water bodies and its abatement by restoration measures in a small catchment area in North-East Germany

Water resources management in NE Germany is still confronted with the consequences of eutrophication. Since the majority of nutrient loading is of diffuse origin, an exact understanding of the various sources is a prerequisite to reducing their impact on surface waters. Control of diffuse pollution demands a “strategy of little steps”, i.e. a variety of numerous measures at different locations in the whole catchment area. The paper describes different nutrient sources, especially those of phosphorus, in a small catchment, provides data on the sources and amounts of pollution and demonstrates proposals and strategies for abatement (e.g. reduction of fertilizers, restoration of wetland and brook stretches, development of ponds). Among the different sources, subsurface water enriched with phosphorus, plays an essential role, because arable soils are oversupplied with phosphorus and the sorption capacity of several soils is nearly exhausted.