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Secrets of the
polluted aquifer

Secrets of the polluted aquifer

The Campo de Cartagena aquifer has since decades been polluted by nitrates. Its waters are also brackish, not suitable for irrigation. Desalting them generates a discharge with nitrate concentrations that are a risk for water bodies such as the Mar Menor.

The Campo de Cartagena aquifer has since decades been polluted by nitrates, a high risk for the Mar Menor.

By Antonio Delgado and Ana Tudela


Remains of rubber drip irrigation tubing that reached the Mar Menor through the Albujón creek / DATADISTA

The area known as Campo de Cartagena is associated to three groundwater bodies: the Carrascoy Triassic aquifer, the Victorias Triassic aquifer and the aquifer also called Campo de Cartagena. The first two have for decades been overexploited, and this has only worsened over time.

Acuíferos de la Comarca del Campo de Cartagena
Location map of the Carrascoy Triassic aquifer, the Victorias Triassic aquifer and the Campo de Cartagena aquifer/ CHS, IGN and own elaboration

The Campo de Cartagena aquifer, the largest of the three, is a multi-layered aquifer, that is, its different levels, one above the other, were formed in successive geological periods. While the lower layers do have a problem of overexploitation because irrigators have looked for water at increasing depths; the upper aquifer, formed in the Quaternary period, is connected to the Mar Menor, and does not have a problem of water quantity, rather the opposite. Seawater intrusion, the filtration of irrigation water, which has increased since the construction of the transfer, as well as periodic intense rains, have made the water table so high that water surfaces on to the ground at some points.

Turn it for a better view

The problem with this aquifer layer is that it is polluted by fertilizer nitrates, one of the great enemies of water masses because it literally fertilizes phytoplankton until it reproduces in such a quantity that it does not allow light to shine through. Waters turn green, as in fact happened during several months of 2016 in the Mar Menor, and the seagrass beds, unable to photosynthesize, die.

300.000 Ton.

Nitrates would actually be helpful for irrigation, as they are fertilizer that would save irrigators money. But it happens that these Quaternary waters are also brackish (they come from filtrations of the Mar Menor, to which the aquifer is connected). They need to be mixed with others of lower salinity or processed in desalination plants to be suitable for irrigation.

Both facts together, salinity and nitrate pollution, are a time bomb. The desalination process generates 70% irrigation-suited water and 30% wastewater, a concentrate of salts and nitrates.

Public Administrations knew this. And they were also aware of the way wells had been drilled for years. Currently, the upper Quaternary period aquifer is not the only one polluted by nitrates. In a document delivered to the CHS by the Campo de Cartagena Association of Irrigators, where they request the reopening of drought wells closed in 2015, it is acknowledged that not only is the Quaternary aquifer polluted by nitrates because it is "under agricultural soil" but that the Pliocene aquifer is also already affected by nitrate pollution in some areas, "especially south of Torre Pacheco, in part due to the artificial connection of the two aquifers that is established through pumping wells. Wells were not properly drilled, going through the Quaternary without cementing the walls of the well in that section, which causes contaminated water to descend from the upper aquifer into the lower.

Turn it for a better view

According to 2018 estimates by the then Ministry of the Environment, 80% of the boreholes in the area were drilled in the wrong way, crossing several aquifers without cementing the passage through the contaminated aquifer, thus causing nitrate-charged water to end up in the lower aquifers as well.

The European Union obliges Member States to protect water bodies from nitrate pollution. Since 1996, Spain has Royal Decree 261/1996 for the protection of waters against pollution caused by nitrates used in agriculture. This legislation is based on European Directive 91/676/EEC.

22 years later, in November 2018, the European Commission opened an infringement procedure against Spain for considering that it insufficiently protects its waters against pollution by nitrates from agricultural sources.

It was not until 2009 that Spain carried out the first census of nitrate-affected waters. In the summer of 2019, months after receiving the letter of formal notice from the European Commission, the Ministry of Ecological Transition has published a public consultation to update the catalogue of nitrate-affected waters. 46% of groundwater bodies in Spain present nitrate pollution. According to the analysis carried out by DATADISTA of this preliminary list, 38% of groundwater in the Segura basin is affected by nitrates or is at risk of being so. Among those affected is the Campo de Cartagena aquifer, where 18 measuring stations show nitrate levels above the legally allowed. The added problem in this case is the interrelation of this aquifer with a protected lagoon, the Mar Menor.

Captaciones vigentes en el Campo de Cartagena
Measuring points installed in aquifers affected by or at risk of pollution by nitrates of agricultural origin on the Campo de Cartagena aquifer / MINISTRY OF ECOLOGICAL TRANSITION

Although the European Union has set a limit of 50mg of nitrates per litre of water, to be reached by 2027, the CHS has been working on the possibility of setting less rigorous targets building on the argument that a drastic reduction of water use would have important socio-economic impacts in the area. Instead of being more ambitious, nitrate concentration objectives have only worsened from one basin plan to another. Thus, if the 2009- 2015 Plan set the 2027 target at 90mg/l, the 2015-2021 Plan, approved a year later, softened the limit to 200mg/l.

Nitrate legislation also establishes that Autonomous Communities must draw up and apply Codes of Good Agricultural Practices that must be compulsory in areas designated as vulnerable to nitrate pollution. In the Murcia Region, these codes were approved for the first time in 1998 and modified in 2003, when Antonio Cerdá served as Councillor for Agriculture, Water and the Environment.

Cerdá, who comes from a family of farmers and is a specialist in soil fertility and plant nutrition, has been the Regional Government's longest-serving adviser to government bodies. He served from 1999 to 2015, being involved in environmental affairs in 1999-2004, 2008-2011 and 2014-2015. He is currently being investigated in the Topillo case, for the alleged commission of crimes of prevarication by omission and crimes against the environment. Reasons are, among others, failure to control and supervise the compliance with the various Codes of Good Agricultural Practices and with their Action Programmes, which were approved by the Department that he himself directed in 2003, 2009 and 2011.

One of the consequences of this lack of control is that Common Agricultural Policy (CAP) subsidies were allegedly granted to farmers who had failed to comply with good practices. This fact, pointed out in the case made by the Public Prosecutor's Office, has involved, in addition to Cerdá, former officers of the Directorate General for the Modernization of Agrarian Operations and Training and of the Regional Coordinating Commission for the Control of Conditionality of Subsidies.

Captaciones vigentes en el Campo de Cartagena
Zones vulnerable to nitrates according to the Law of Urgent Measures for the Mar Menor, approved in 2018.

The lack of control and the 2016 eutrophication episode in the Mar Menor led to the approval, two years later, of a new law to regulate the agricultural and livestock sector in the proximity of the lagoon. In 2018, the Regional Government of Murcia approved the Law of Urgent Measures for the Mar Menor in which three zones vulnerable to nitrate pollution are established, with different restriction levels, zone 1 being the most sensitive and restrictive. This law also prohibits the use of highly soluble and potentially polluting fertilizers such as ammonium nitrate, calcium nitrate and urea. Among other measures, the law foresees that, in the event that a desalination plant is approved, it must implement a system to reduce the nitrate concentration of the brackish waters.

Environmentalist associations such as Ecologistas en Acción, ANSE or the platform Pacto por el Mar Menor have reported that this legislation is not being complied with, and have documented unlawful agricultural activity in the Campo de Cartagena, such as manure accumulations, downslope ploughing or the lack of vegetative structures to control runoff and nitrate absorption.

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