File:The Lagoon of the Seven Cities.jpg

English: According to an ancient legend, Lagoa Azul (Blue Lake) and Lagoa Verde (Green Lake) in the Portuguese archipelago of Azores, were formed when a blue-eyed princess and green-eyed shepherd were set apart. The tears both shed because of their misfortune formed two lakes with the colours of their eyes. The beautiful pallet displayed by the two lakes tells another story – a story of how the destruction of forested areas, their transformation into grassland and pasture increased the runoff of nutrients (in particular phosphorus and nitrogen). The lack of domestic sewage system (back in the mid-20th century) and the increased pressure on the ecosystem led to the eutrophication of the lakes as a result from nutrient enrichment fuelled by human agriculture and domestic activities. This image, acquired by one of the Copernicus Sentinel-2 satellites on 25 June 2017, shows the “Lagoon of the Seven Cities”, the twin lake located in the crater of a dormant volcano. High-resolution data acquired by the Copernicus Sentinel satellites can be used to support EU Green Deal policies for clean water by monitoring biodiversity and pollution in lakes. Image by Sara Aparício