The Portuguese Environment Agency (APA) challenged the data from the Movimento pelo Tejo – proTEJO and the ZERO association regarding the minimum flows of the Tagus River, stating that there were no zero-flow days in the hydrological year 2025/2026.
In a statement sent to the Lusa agency, following the alert issued by the two environmental organizations, the APA maintains that the values presented do not correspond to the data used to verify compliance with the flow regime established by the Albufeira Convention.
ProTEJO – Movement for the Tagus and the environmental association ZERO warned, on October 1, that the daily minimum of 1 cubic hectometer (hm3) per day agreed between Portugal and Spain was not met on 14 days of the hydrological year 2025/2026, five of which with zero flow.
The organizations based the analysis on data from the National Water Resources Information System (SNIRH) relating to inflows to the Fratel reservoir between October 1, 2025 and September 28 of this year.
The APA counters that the Albufeira Convention defines the Cedillo dam, in Spain, as the control section for flows from the neighboring country, with the volumes released there serving as the reference for assessing Spain’s compliance obligations.
According to the agency, the SNIRH data used by the environmentalists correspond to estimates of inflow to the Fratel reservoir, provided in real time and “prone to temporary faults”, and subsequently subjected to technical validation.
The daily regime sets a minimum of 1 hm3 per day at Cedillo and, in Belver, already in Portuguese territory, 1.05 hm3/day between May and November and 1.30 hm3/day between December and April.
Although challenging the reading presented by proTEJO and ZERO, the APA acknowledges that real-time data recorded at Cedillo showed five days with values below 1 hm3/day, four of which were above 0.90 hm3.
In Belver as well, five days were recorded below the 1.05 hm3/day threshold, with one of them registering 1.01 hm3.
The agency stresses, however, that there was no day with zero flow recorded at Cedillo, Belver or Almourol, with the lowest daily value at the latter hydrometric station being 2.5 hm3, in September.
The APA concludes that the available data “do not show any zero-flow situation on the Tagus River” in the hydrological year 2025/2026 and argues that the assessment of compliance with the Convention should be based on officially defined control sections and on validated data.
The APA adds that this was the first year of application of the current daily regime, and that the concessionaires responsible for the hydraulic infrastructures of the two countries have been alerted to cases of non-compliance or approaching the established limits.
According to the agency, these situations are monitored by the Portuguese and Spanish delegations within the scope of the monthly meetings for implementing the flow regime of the Albufeira Convention.
In the position released last week, proTEJO and ZERO demanded the Portuguese Government to recognize the days of zero flow or below the minimum and to urge Spain, within the framework of the Commission for the Application and Development of the Albufeira Convention (CADC), to ensure effective compliance with the daily minimum flow.
The two organizations also advocate replacing the current system with a regime of ecological, continuous, and regular flows, considering that the minimum volumes can be released in a concentrated manner without guaranteeing the regularity needed by the Tagus ecosystems.
