Groundwater atlas for pesticides

The atlas on the presence of active substances and degradations products of pesticides in groundwater in the Netherlands is to be used in assessing authorising crop-protection products and drinking-water abstraction in the country. With this TKI Delta technology project, Wageningen University & Research is contributing toward sustainable water management.

Reason for the project

The Netherlands currently lacks a tool that can provide an overview of all the monitoring results of pesticides in groundwater. As a result, the CTBG has insufficient access to data concerning the occurrence of pesticides in groundwater in their authorisation evaluation of crop protection agents. Commissioned by the Ministry of Economic Affairs, Alterra is developing the atlas for pesticides in groundwater in collaboration with RIVM. The first version of the atlas is primarily intended for use in authorisation assessment by the CTBG. Vewin is involved with this BO project through the Soundboard Group and would like to present drinking-water companies’ monitoring results to the CTGB. In 2016 it gave Alterra a separate assignment to get the transferral of data from water companies using ground water for drinking-water production on the right track. Eight water companies are participating in this Vewin project. The transfer of data is accompanied with intensive collaboration between water companies and the atlas developers. The systems for storing and managing data differ for each water company and have never before been combined with each other in this way. The atlas developers are responsible for monitoring the quality and consistency of all of the data in the atlas. As soon as the first version is put into use, the question will then be how to keep this tool up to date. Achieving this will require a supplement to the Vewin project. This project proposal delivers a number of additional products for the water companies wishing to deliver data for the atlas in the future as source holders.

Aim of the project

Vewin and the water companies have expressed the desire that periodic updates of the atlas entail considerably fewer costs than the first transfer of monitoring-network data and results. They primarily see the Vewin project as a one-off investment. The aim of the collaboration is to guarantee the transfer of water-companies’ data to the atlas and to make it possible for this process to run efficiently. The second aim is to increase familiarity with the tool outside the drinking-water sector.

This research directly contributes to the policy objectives of protecting ground-water quality and retaining a broad package of resources for agriculture and horticulture. In the long term, using a high-quality tool such as this ground-water atlas in the authorisation evaluation directly results in fewer vulnerable extractions being closed and indirectly results in less use of surface water for drinking water production. This research ultimately contributes to a better quality of both ground and surface water.

Planned activities

The project results in a protocol and a tool for the source holders to use. This procedure is described in the protocol followed in 2016 for processing the data originating from the water companies’ systems – and from the laboratories these companies work with – so that these comply with the specification of the atlas. It is established for each source holder which choices have been made when selecting measurement locations, measurement rounds and parameters/substances. The source holders are provided with an Input Validator serving as a tool with the technical validation and temporary storage of data to be transferred.

Future updates lead to new database versions being released. In this respect, Alterra bears responsibility for monitoring the quality and consistency of all of the data as a whole in the atlas, with the Input Validator also falling under the version management of the atlas. Vewin and Alterra are discussing how the collaboration in the period from 2017 concerning future updates can be organised and how the required commitment from Alterra and RIVM can be financed.

Exptected results

The TKI project is a supplement to the current Vewin project and leads to the following results:

  1. A protocol for the regular transfer of the date of water-companies to the atlas for pesticides in groundwater (Alterra report)
  2. A tool for the source holder for validating new and/or supplementary data in the event of updates. With this Input Validator, the source holder itself is able to gauge the validity of the data based on the protocol (identifying substances and relationships between substances, range, format, domain and other specifications).
  3. Dissemination Round, the date of the release is publicised through trade journals and other channels. An article in H2O on the first version of the atlas for pesticides in groundwater. The tool could also be used for other policy objectives. The article also examines prospects in a broad sense, such as the possibilities for using the atlas for other groups of users or supporting other policy objectives.
  4. In collaboration with Vewin request feedback from the water companies concerning the process, using the atlas and corresponding tools. Processing this information into future updates with new data from water companies and into proposals for new functionality (period from 2017).


The Netherlands is lacking a tool that provides an up-to-date picture of the presence of active substances and degradation products of pesticides in groundwater. The atlas takes care of this gap and makes it possible to develop guidance for evaluation by the CTGB. This tool could also be used for other policy objectives such as sustainable crop-protection policy, water framework directive (KRW) reports and decision-making on monitoring programmes. For instance, the instrument is able to efficiently facilitate analyses focused on sampling. In the future there are possibilities for connecting with the subsurface key register (BRO) and to meet the demand for variants for the measurement results of other substance groups in groundwater originating from the same measurement networks – partially or otherwise – such as nitrate and new substances.

Knowledge transfer

This research and the collaboration between Vewin and Alterra are specifically focused on guaranteeing a routine update of the atlas for pesticides in groundwater. In addition to the proposal for the BO project and the Vewin project, this research results in the enduring involvement of Alterra in helping protect the use of groundwater as drinking water. In the long term, this could directly result in fewer vulnerable extractions being closed while indirectly leading to less surface water being used for producing drinking water. The atlas makes it possible to further refine the authorisation evaluation or substantiate it scientifically and thus contributes to retaining a broad package of resources for agriculture and horticulture.