The investigation 'Under the Surface' is based on open data released by member countries to the European Environment Agency, which is freely accessible on the latter's website. This data has been instrumental in producing an interactive map and a series of static maps, providing a comprehensive overview of the third hydrological planning cycle (2021-2027). The data, primarily updated to 2021 , is a significant resource for understanding the current state of European water bodies.

The data used in this investigation are the official submissions from member states to the European Environmental Agency. As such, they are as reliable as the systems used by the member states and the institutions responsible for this 'data cycle '. However, it's important to note that in some cases, experts consulted by the consortium of journalists expressed doubts about both the quality and quantity of the available data.

The map serves as a valuable tool, providing a snapshot of the current situation of most of the EU's water bodies. However, it's important to remember that the methods used by member states to collect the data may vary, making direct comparisons difficult or inappropriate. Therefore, it's essential not to interpret the data literally, but rather use it as a starting point to gather different stories on the ground, as all the involved journalists did.

The map shows the water bodies' health status and the reasons behind their eventual poor condition. Water bodies are classified as being in good status only if both quantitative and chemical dimensions are suitable. The map does not show changes and trends over time. Thus, since the data is related to the third cycle, it does not tell us which water bodies have improved or worsened. It only tells us about their condition at the time when the data was collected, presumably by the end of 2021.

Theoretically, a water body might have improved in quantity and quality compared to the last monitoring cycle, but it still appears red on the map. The red colour is due to the fact that legal limits (50 mg/L for nitrates and 0.1 μg/l for active substances of pesticides and their relevant metabolites or 0.5 μg/l for the total sum of all identified and quantified pesticides/metabolites) have been exceeded.

It's important to remember that the groundwater map does not show the water quality from our taps. In Europe, we generally do not drink raw water. However, since groundwater in the EU represents 65% of urban water supply (and 25% of water for agricultural irrigation), there is a direct correlation between groundwater and drinking water. The poor chemical status of groundwater may mean that this water must be treated before reaching our homes or that a particular water basin is unsafe for public consumption.

The interactive data will be updated as new public data becomes available.

The map shows the most up-to-date information on the problems affecting our groundwater. Based on the same data, European authorities require member states to improve protection measures for water bodies in poor condition. The red zones on the map, which indicate water bodies in poor condition, highlight areas where member states will need to implement corrective measures to reverse the situation to reach "good status." In other words, national authorities must alleviate the pressures that put water bodies at risk, by adopting measures that limit the use of pesticides or fertilizers in a designated area or limiting water extraction for industrial or agricultural irrigation use.

Data collection and methodological aspects

The interactive map (which includes the status of water bodies and the impacts that caused them) shows the situation of groundwater bodies reported by member states to the European Commission after the preliminary work for the Third Water Cycle Management Plans (2022-2027).

The information was obtained from the structured data that member countries must report to the European Environment Agency. This data includes XML files and spatial data in vector format for each groundwater body, with the declared status and impacts (among other variables). An XML parser was used to extract, transform, and load (ETL processes) the essential data from each water body, and this information was unified with the most recent available spatial data (the geometry of each groundwater body).

In some areas, multi-layer aquifers may exist, meaning several groundwater bodies exist at different depths and types (for example, an upper unconfined aquifer and another confined one beneath it). In our visualizations, the order provided by the spatial data attribute table was respected.

Member States have not standardized their monitoring networks and measurement methodologies regarding the density of monitoring points and the data quality provided. Countries also highlighted shortcomings in meeting reporting deadlines.

The European Commission has urged countries to improve monitoring information at monitoring points (piezometers and quality meters) and well flow meters (to know the actual volume of water extracted). The Commission also urged countries to increase the number of water bodies monitored, reducing the size of each body to facilitate studying its evolution. This would make it harder to delay declaring a water body in poor condition when it is only partially deteriorated.

How the status is defined as good or poor

According to the objectives defined in the Framework Directive, to achieve "good status," groundwater must be assessed in two aspects: good quantitative status (that is, the water body's ability to recover its levels during the water cycle) and good qualitative or chemical status (not exceeding certain levels of chemical elements, including saline intrusion, which makes the water undrinkable).

A water body is considered in poor condition only if it has been caused by anthropogenic reasons—human actions—either through a rate of extraction exceeding the water level's recovery capacity or activities that cause pollution. If a water body is in poor quantitative or chemical condition (or both), it is considered to be in poor overall condition.

Impacts

The main impacts associated with the poor status of a groundwater body are excessive extractions that affect the aquifer level, impacting its quantitative status (identified with the letter L on the map). Regarding qualitative or chemical status, the impacts can be nutrient pollution, mainly nitrates from agricultural fertilizers and animal waste reaching levels above or close to 50mg/l (N); pollution from chemicals other than nutrients, mostly pesticides and herbicides but also metals, hydrocarbons, etc. (C); microbiological contamination (M); and organic contamination (O). Only a limited number of substances are monitored at the EU level. The list of contaminants of interest (and their environmental standards) is defined within Annex I of the Groundwater Directive, which complements the Framework Directive and should be reviewed every six years. Member States must establish threshold values for substances of national interest, including, where relevant, those listed in Annex II of the Groundwater Directive. Furthermore, the poor status of a groundwater body that affects the chemical or quantitative quality of a connected surface water body (Q) or a terrestrial ecosystem dependent on that groundwater body (E) is identified as an impact.

"Under the Surface" is a collaborative project initiated by the Spanish investigative team Datadista, which was the first to collect the data and build a database that could be consulted at a European level. Journalists and media from other countries analyzed the data and conducted field investigations, reporting on the impacts and causes of the degradation and decline of European water bodies.

The project was launched by Arena for Journalism in Europe and Datadista. The idea was born in 2023 during the European investigative journalism conference Dataharvest. Inspired by previous investigations on water by the Datadista team in Spain, Arena invited a group of European journalists during its Climate Arena Conference in November 2023 to build a collective project. After sharing methods and objectives, the team of 14 journalists began working last January.

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