Nitrate in surface water

  • Average nitrate concentration increasing again in recent years

    In the winter year of 2019-2020, the average nitrate concentration in surface water in agricultural areas in the Flemish Region was 21,6 milligram (mg) nitrate per litre. The average nitrate concentration decreased from 2005-2006 until 2013-2014. It remained stable until 2016-2017, but has since risen again.

  • Share of monitoring sites exceeding threshold value increased since 2016-2017

    In the winter year 2019-2020, 32% of monitoring sites exceeded the threshold of 50 mg nitrate per litre. The share of monitoring sites exceeding the threshold value decreased between 2005-2006 and 2013-2014. After one year of stabilisation the share of sites with an exceedance increased again.

    The dry summers of 2017, 2018 and 2019 were followed by more exceedances of the threshold in the subsequent winter periods. Dry summers result in less uptake of nitrogen by agricultural crops and consequently to higher soil nitrate stocks. If the low uptake in the summer period is not taken into account in the crop selection and fertilisation, the nitrate stock is washed out in the winter period.


Environmental report (MIRA), Flanders Environment Agency (VMM): Nitrate in surface water 


Winter year: a winter year runs from 1 July of a calendar year to 30 June of the following calendar year. 

Publication date

20 January 2021

Next update

December 2021

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