Restoration of Botshol (The Netherlands) by reduction of external nutrient load: Botshol and the Dutch governmental program of nutrient reduction

Abstract

In the nature reserve Botshol, the process of eutrophication is very successfully stopped and reversed by hydrological separation of the agricultural area from the nature reserve and by dephosphorizing the inlet-water. The external phosphate loading of about 0.6 g Pm−2y−1 decreased 80% to about 0.12 g Pm−2y−1. The Dutch governmental program in relation to eutrophication is focussed on the introduction of detergents without phosphates, dephosphorizing the water at sewage purification plants, reduction of fertilization of farming lands and international measures in relation to the discharge of phosphates in the rivers Rhine, Meuse and Scheldt. The effects of the governmental program on the external phosphate loading of Botshol will be a reduction of only 4%.