Pesticides were assessed against effect or quality thresholds between 2013 and 2021. One or more pesticides were detected above their effect threshold at 10% to 25% of all surface water monitoring sites. Exceedances were often caused by the insecticide imidacloprid, and the herbicide metolachlor. Exceedances of one or more pesticides were detected at between 4% and 11% of groundwater monitoring sites, mainly by atrazine and its metabolites and bentazone. Differences in weather, crop type and reporting mean that changes between years may not be significant.

Figure 1. Percentage of reported monitoring sites with pesticides exceeding thresholds in a) surface waters and b) groundwater in Europe, weighted by country area

Percentage of reported monitoring sites with pesticides exceeding thresholds in a) surface  waters and b) groundwater in Europe, weighted by country area

Pesticides can contaminate surface waters and groundwater and if their concentrations are above critical thresholds, they can be harmful to the environment.

The European Green Deal sets targets to reduce the use of and risks from chemical pesticides by 50% by 2030 in the Zero Pollution Action Plan, Farm to Fork and Biodiversity strategies, with a focus on protecting ecosystems and improving biodiversity.

The Water Framework Directive (WFD) sets environmental quality standards for pesticides in surface water. To assess the chemical status of groundwater, a precautionary quality standard of 0.1µg/L is set for pesticides according to the Groundwater Directive, reflecting the desire to keep pesticide concentrations in groundwater at low levels.

Figure 1 shows that in 10% to 25% of all surface water monitoring sites, one or more pesticides were detected above the effect threshold each year between 2013 and 2021. Exceedances of one or more pesticides were detected at between 4% and 11% of groundwater monitoring sites.

Pesticides most often causing exceedance in surface waters are the insecticide imidacloprid and the herbicide metolachlor, some of which were no longer approved for use in plant protection products during the monitoring period. The proportion of monitoring sites with exceedances has decreased by more than half from 2020 to 2021 (Figure 1). Reporting from large countries with few monitoring sites, with fewer exceedances in 2021, may explain part of this decrease owing to weighting by country surface area.

In groundwater, the herbicide atrazine and its metabolites as well as bentazone caused most exceedances. Atrazine was not approved for use in plant protection products during the monitoring period. Despite restrictions on atrazine since 2007, it continues to be found in groundwater because it is very persistent. Bentazone is currently approved until May 2025 and is under review to determine if approval can be renewed.

Losses from the application of pesticides may vary considerably between years, depending upon, for example, crop type and the weather, while the frequency of monitoring of pesticides in surface waters can be limited to one year out of three. In addition, characteristics of the monitoring campaigns (e.g. number of samples taken annually, number of pesticides monitored, number of monitoring sites) may vary from year to year. Changes to the approval status of pesticides influence their use and presence in water, which can also lead to difficulties in interpreting trends over time. For these reasons, changes between years may not be significant.

Figure 2. Percentage of reported monitoring sites with pesticides exceeding thresholds in surface waters, different sized rivers, lakes and groundwater in European countries, 2016-2021

Percentage of reported monitoring sites with pesticides exceeding thresholds in surface waters, different sized rivers, lakes and groundwater in European countries, 2016-2021

Figure 2 focuses on the more recent, shorter period between 2016 and 2021, where pesticides were reported from a total of 9,505 monitoring sites for surface waters and 13,328 sites for groundwater. The number of sites with data reported for surface waters varies by country from less than 10 (Hungary, Iceland, Luxembourg, Romania, Sweden, Switzerland) to more than 1,000 sites (France, Italy, Spain). There is similar variation in groundwater monitoring sites: numbers range from 33 in Lithuania to over 3,000 sites in Italy (with over 1,000 in Austria, France, Germany, Spain).

The number of pesticides reported in surface waters ranges from fewer than ten substances (Austria, Iceland, Romania, Switzerland) to more than 100 substances (Belgium, Czechia, Finland, France, Germany, Italy, Netherlands, Spain). For groundwater, the lowest number of pesticides monitored was reported from Austria (6) and the highest number from France (242).

Exceedance rates of more than 30% were reported in 8 out of 30 countries for surface waters and in none of 21 countries for groundwater.