Tagus River flow falls below minimum agreement with Spain

Environmental organizations proTEJO and ZERO have reported that the Tagus River has failed to maintain the minimum daily water flow agreed upon between Portugal and Spain. According to data from the National Water Resources Information System (SNIRH) regarding inflows to the Fratel reservoir, there were 14 days between October 1, 2025, and September 28, 2026, where the flow fell below the agreed minimum of 1 cubic hectometer (hm³) per day, which is approximately 11.6 m³/s.

The report highlights that five of these days recorded zero flow. On August 21, the average daily flow at Fratel was measured at only 0.68 m³/s, representing roughly 6% of the required minimum. These findings contradict a 2024 commitment made by the Minister of Environment and Energy, Maria da Graça Carvalho, who stated that the days of zero flow in the Tagus had ended following a bilateral agreement to ensure daily flows from the Cedilho dam.

While the Albufeira Convention allows for compliance based on annual, quarterly, or weekly volumes—permitting concentrated discharges followed by periods of very low flow—the organizations argue that the 2024 commitment was intended to ensure daily regularity. They maintain that the current situation does not fulfill the binding agreement to distribute the 7 hm³ weekly minimum across all seven days of the week.