Nutrients are important feeding elements for the fauna and flora. They exist in all fertilizers and are applied in agriculture. If too high concentrations of nitrogen and phosphorous compounds are discharged into surface water bodies, they impact on water quality by massively developing algae, e.g. in the Ijsselsea.
During the past years, improved wastewater treatment and the introduction of phosphate-free detergents have considerably contributed to reduce the influence of the nutrient input of wastewater origin into the watershed of the Rhine. In 2016, 272,156 tons of total nitrogen were discharged into the estuary of the Rhine, the coastal waters and the Wadden Sea. One third through wastewater conducts and two thirds were of diffuse origin. In 1985, the amount was more than 443,000 tons.
In future, measures aimed at reducing the eutrophication of waters must above all include the reduction of diffuse nutrient inputs of agricultural origin.