In the Bergambacht polder in The Netherlands, the surface water system is highly eutrophic. Owing to this high nutrient concentration, duckweed grows abundantly. To reduce the nutrient concentrations in the surface water, remedial measures are needed. To predict the effectiveness of three measures, a combination of a nutrient leaching model and a water quality model for nutrients in the surface water system was used. The scenarios formulated on the basis of these measures were simulated over a period of 35 years. Removing duckweed results in a substantial reduction of nitrogen and phosphorus. Improving the water purification plants results in a small reduction in the average nutrient concentrations. Dredging the total sediment layer results in a large reduction of phosphorus concentrations, but leads to an increase in nitrogen concentrations. The three measures combined will not improve the nitrogen concentration 30 years after implementation, but the phosphorus concentration will be reduced by 80% compared with 1990.

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