Beach closures can occur after heavy rain. | Miquel À. Cañellas

A report from the Prosecutor's Office for the Environment has confirmed that wastewater discharges without treatment or with poor treatment have been been polluting the bay of Palma at levels above the legal limit.

Since 2018, a Palma court of instruction has been investigating alleged illegal contamination by water discharges managed by the Emaya municipal services agency. The court requested a report from the Prosecutor's Office with information provided by Emaya, the regional environment ministry and the Guardia Civil's Seprona division. Another report was commissioned on the degradation of the marine ecosystem, with special attention to the deterioration of posidonia sea grass, the accumulation of pollutants on the seabed and the presence of heavy metals.

The Prosecutor's Office has concluded that the wastewater network in Palma and neighbouring municipalities is obsolete. In the specific case of Palma, it was designed for 250,000 inhabitants, whereas the population is now around 450,000. This rises to 800,000 in the summer.

Due to the fact that the rainwater and wastewater networks have been linked, the capacity is insufficient. As a consequence, the system "overflows" more or less every time there is significant rainfall. The two treatment plants do not have the capacity to cope with the mixture of rainwater and wastewater. There are, therefore, uncontrollable discharges into the bay. Between 2003 to 2018, an average of 78 such episodes occurred each year.

The report refers to discharge into the sea from the treated water outfall. This has been done for half a century. However, it lacks the mandatory authorisation from the Balearic government, as it does not comply with state regulations on wastewater treatment. Despite this, the regional environment ministry has never sanctioned these breaches.

Meanwhile, researchers from the Spanish Institute of Oceanography and the Spanish Geological and Mining Institute, who have undertaken the separate report, conclude, among other things, that: "There is more than enough evidence to confirm that wastewater discharges from the outfalls that discharge into the bay of Palma are implicated in a profound deterioration of the habitat in the study area."

Work has since been started on improvements, and Palma town hall, the Balearic government and the national ministry for ecological transition have agreed on the construction of a new treatment plant with twice the capacity. This is due to be completed in 2026.