River Tejo minimum flow agreement breached 14 times in past year, environmental groups say
A cross-border accord meant to guarantee water in the Tejo river has failed on 14 days over the last year, according to environmental groups who marked Portugal's National Water Day with a call for urgent government action.
Data from Portugal's National Water Resources Information System show that between 1 October 2025 and 28 September 2026, the minimum daily flow of one cubic hectometre was not met at the Fratel reservoir on nearly two weeks of days. On five of those days, the river ran at zero flow.
What the data shows
The environmental associations proTEJO — based in Vila Nova da Barquinha, in the Santarém district — and ZERO analysed official figures and found the 2024 agreement between Portugal and Spain has not delivered what was promised.
The worst single day came on 21 August 2026, when the average daily flow reaching Fratel was just 0.68 cubic metres per second — roughly 6% of the minimum agreed. A separate sharp drop was recorded between 30 June and 1 July, when flow plummeted from 197.05 cubic metres per second to just 9.69 cubic metres per second.
"They did not meet the cubic hectometre that was foreseen in this new agreement," Paulo Constantino, spokesperson for proTEJO, told news agency Lusa. He described the 2024 commitment between the two countries as "binding".
The 2024 accord
In September 2024, Portugal and Spain reached a principle of agreement on Tejo flows, later formalised at the 35th Luso-Spanish Summit the following month. Spain committed to releasing at least one cubic hectometre of water per day from the Cedillo dam, while Portugal agreed to ensure minimum flows from the Belver dam — 1.05 cubic hectometres per day from May to November and 1.30 from December to April.
At the time, Portugal's Minister of Environment and Energy, Maria da Graça Carvalho, declared that "the days of zero flow in the river Tejo" had ended.
The agreement, reached in Aranjuez, aimed to distribute a weekly minimum of 7 cubic hectometres across all seven days — roughly equivalent to 11.6 cubic metres per second.
Why daily minimums are not enough
Constantino warned that even when the daily minimum is technically met, the current system allows water to be released in concentrated bursts over a few hours, leaving the river starved for the remainder of the day.
"It is not sufficient," he said. He advocates replacing the current minimum-volume regime with continuous ecological flows — regular, scientifically-grounded water releases that mimic the river's natural variations.
The consequences of abrupt flow fluctuations are particularly severe for fish species during migration and spawning periods. Constantino explained that rising water can enable fish to lay eggs in certain areas, but a subsequent drop leaves those eggs exposed and destroyed.
Formal demands
In a joint statement, proTEJO and ZERO demanded that the Portuguese government formally acknowledge the days when flow was null or below minimum, and raise the issue with Spain through the Commission for the Application and Development of the Albufeira Convention.
The associations want Portugal and Spain to establish ecological flow regimes for the Tejo, monitored daily and integrated into the River Basin Management Plans for the fourth cycle covering 2028–2033.
European complaint ongoing
The Tejo movement has been pursuing accountability at European level. In March 2026, it appealed to the European Ombudsman over what it called "maladministration" and "excessive delay" by the European Commission in responding to a complaint filed in March 2024.
That original complaint, signed by 31 Iberian organisations, alleged that Portugal and Spain were failing to meet ecological flow requirements in violation of the Water Framework Directive and the Albufeira Convention.
In March 2026, the Commission issued a definitive response, archiving the complaint and referring Tejo issues to "generic bilateral dialogues" between the two countries. The European Ombudsman, Teresa Anjinho, closed the case without opening an inquiry.
proTEJO challenged that decision in June 2026, accusing the Commission of a "manifest error of assessment" and announcing plans to escalate the matter to the European Parliament and the Court of Justice of the European Union.
For residents and river users
The degradation of Tejo flows affects more than ecosystems. Low water levels create difficulties for farmers in the Médio Tejo region who need water for irrigation. River tourism also suffers, as boats require certain water depths to navigate, and changing sandbanks from previous floods can make navigation hazardous.
The groups also warn that 93% of dams in the Tejo basin lack defined ecological flow regimes, and 98% of large dams have no fish passage devices. Groundwater quality has also deteriorated, with the percentage in good state falling from 90% to 60% between recent planning cycles.
