Report confirms low bacteria levels in the Bay of Portmany

ABAQUA presents a study conducted alongside IMEDEA and FUEIB that analyzes 15 years of data and confirms that the state of the water ensures the conservation of the ecological value of the bay.

The Balearic Water and Environmental Quality Agency (ABAQUA) has published a technical report on the Bay of Portmany (Ibiza), prepared by the University-Business Foundation of the Balearic Islands (FUEIB) together with the Mediterranean Institute for Advanced Studies (IMEDEA). The study, focused on water turbidity and microbiological quality, compiles recent data and consolidates information from various sources to better understand the current state of this coastal environment. The report confirms that the Bay of Sant Antoni is subject to natural and human influences that temporarily affect water quality. However, the observed values do not indicate a critical or irreversible situation.

The study combined various tools and types of information to assess the condition of the waters, including: sampling campaigns from boats and coastal points; review of hydrochemical and microbiological records spanning more than 15 years (2008–2024); use of satellite imagery from Sentinel-2 between 2018 and 2024; incorporation of physical models with data on ocean currents, wind, and waves; and analysis of groundwater quality at more than ten points near the coast.

In total, dozens of data series were considered, along with several on-site campaigns, more than 50 satellite images, and multiple layers of environmental and urban information. All of this allowed for an accurate picture of the bay’s behavior, both under normal conditions and following episodes of rain or wind.

The analysis confirms that turbidity increases with heavy rainfall and resuspension of the seabed, especially in the northern part of the port, although under normal conditions it remains within the usual levels for an urban bay. As for microbiological quality, bacterial levels are generally low and comply with regulations, with minor fluctuations in specific areas. Nutrient and phytoplankton concentrations fall within typical Mediterranean values, although occasional increases are detected after certain events that can lead to small algae blooms. Meanwhile, seagrass meadows, though fragmented in some areas, still maintain a significant presence, especially in deeper or less disturbed zones.

The report highlights that, despite the pressures on the ecosystem, the current situation allows room to preserve its ecological and social value.

Based on these data, the study proposes simple and achievable measures to prevent further deterioration in the future. Among the recommendations, ABAQUA emphasizes the advanced stage of the approval process for the high-level sanitation system renewal project in Sant Antoni de Portmany—from the urban center to the Ses Païsses wastewater treatment plant (EDAR)—currently in its final authorization phase, as well as the future installation of a Water Reuse Station in Ses Païsses. Both projects have secured funding through the most recent 2024 ITS call.

In addition, the report highlights the operational restoration of the Caló de S’Oli outfall, completed in 2024, and the ongoing tender for its structural repair, which includes anchor replacement and realignment of the section located more than 34 meters deep.