Los Alcázares Town Council has reassured residents after parts of the Mar Menor turned bright green on Monday, 24 August. Images of the unusual colour spread across social media, prompting concern about whether the lagoon had been polluted.

The council has said the colour was caused by a natural, harmless dye used during filtration tests on the local sewerage system. The tests are being carried out by Pronorte as part of ongoing sewerage works in Los Alcázares, and some of the product reached the Mar Menor.

Checks carried out after the incident was reported found that the dye poses no risk to bathers, marine life or water quality. The council said the colour should gradually disappear and stressed that the incident should not be confused with a pollution event.

The municipality thanked residents who reported the unusual colour and the emergency services that responded to enquiries. It added that formal proceedings would be opened if future checks found contamination or any breach of environmental regulations.