After several months of monitoring, the summer is ending on a rather favorable note for the Pli Ouest aquifer. The rains in August and a generally well-watered 2026 are helping to maintain high groundwater levels across much of the area. At the Vise spring, the flow remains exceptional for late summer.
August was wetter than normal in the Thau territory, recording 43.4 mm of rain, 65% above average. A significant rainfall event on August 24 and 25 brought between 18 and 35 mm of rain depending on the sector. This late summer follows a generally well-watered year, with a rainfall surplus of 61 mm (+11%) for the 2026 hydrological year and 97 mm (+34%) since January.
These rains have had a positive effect on the Pli Ouest aquifer. In Villeveyrac, levels are among the highest observed for an August since 2020, with the August 24 event causing a rapid rise of 1.8 m. Levels are also considered high in Plaissan and Balaruc-les-Bains, and moderately high in Montbazin-Issanka.
The underwater source of La Vise, located in the lagoon of Thau, shows a remarkable flow rate for the season. As of August 31, it still reaches 143 liters per second, a value described as very significant, even exceptional. Freshwater pressure also remains significantly higher than the lagoon level, with a safety margin between 124 and 135 cm, a key indicator for assessing the risk of 'inversac' (saltwater intrusion into the aquifer).
At the end of this summer 2026, indicators are therefore favorable for the Pli Ouest aquifer. The Syndicat mixte du bassin de Thau (SMBT) and its partners continue to regularly monitor the evolution of this strategic water resource for the territory.
