Excessive nutrient loads in rivers and lakes have adverse effects on ecosystem functioning and human activities. The International Rhine Committee has tried to reverse this trend by formulating emission reduction objectives. One of the human activities that may benefit from this is water production that uses surface water as its main source. This paper explores whether reductions in nutrient loads in the Rhine basin result in changes in (the intensity of) treatment activities by the water treatment plant of the Water-transport-company Rhine-Kennemerland (WRK) at Andijk, the Netherlands. For this purpose, a regression analysis was performed on data from 1990–1995 to find a quantitative relationship between the water quality objective for the end product on the one hand, and water quality parameters in Lake IJssel and various treatment processes on the other hand.
In the years 1985–1995, phosphorus loads to Lake IJssel reduced by 50% as a result of significant abatement efforts in the Rhine river basin. As a result, chlorophyll-a concentrations decreased by less than 10%. Further phosphorus emission reductions in the Rhine river basin, for example 75% by the year 2000 as is the objective in the Rhine Action Programme, are expected to result in a 30% decrease in chlorophyll-a concentrations compared with the levels of 1985. These reductions in chlorophyll-a concentrations can be expected to have some impacts on the water treatment plant of WRK at Andijk. However, as they constitute less than 1% of production costs, the monetary benefits of these reductions are limited.