During the hottest stretch since records began in 1965, Spanish irrigation experts monitor water use as they rely on every drop to feed fields. Data from the Ministry for Ecological Transition and Demographic Challenge shows that 34.2 percent of the remaining reserves in the marshes are about to be drawn down in the basins as a new cycle begins. The border with Portugal marks a priority for the Duero, Guadiana, Tajo and Miño-Sil basins to complete their annual tribute under the Albufeira Treaty. In cases where specific quantity data are not formally published, figures follow the treaty provisions.
The 1998 Albufeira Treaty remains the framework that governs how much Spanish reservoirs contribute to Portuguese reserves based on rainfall. If the year is dry, the transfers are reduced to reflect that reality. Yet problems arise when the share barely meets expectations, as happened in 2022. This year the rate stood at 67.88 percent, according to irrigation associations quoted by El Periódico de España. The public stance is clear: there is no reluctance to contribute, and the practice has always been seen as reasonable. Still, a fixed contribution of 67 percent to 85 percent is not sensible in a changing climate. The treaty is well over two decades old and needs updating, notes Manuel Mantecón, general secretary of the Duero Basin Irrigation Communities Association. He spoke to the newspaper about the evolving environmental and agricultural context.
The basins covered by the treaty show varying levels of capacity use: Miño-Sil at 46.7 percent, Tajo at 36.7 percent, Duero at 35.8 percent, and Guadiana at 23.9 percent. This last basin is facing one of the driest stretches in memory, with sharp uncertainty about future water availability. Forecasts from Aemet suggest that high temperatures will persist into autumn, and rainfall in central and western regions may fall 40 to 60 percent short of typical levels.
Farmers express frustration about the campaign results. They have measured water use to build reserves for next year’s harvest and feel disappointed when savings are drawn down at the end of summer. The irrigation cycle in both countries has effectively ended, reducing flexibility for future seasons. The concerns are shared by Mantecón, who reiterates the need to safeguard future irrigation against shortfalls.
According to the latest report from the Ministry dated September 13, Spain’s water reserve stands at 34.2 percent of capacity, having fallen by 0.8 percent in a single week. In Zamora, the program for reporting discharge by the Duero Hydrographic Confederation to MITECO would leave the Ricobayo reservoir at only 16 percent of its reserves.
Performances in Leon
In León, the Almendra reservoir, which serves roughly 12,000 residents, will be asked to release 400 cubic hectometers in September, nearly half of the current reservoir volume. The Tormes River, feeding this reservoir, flows into the Duero basin. Nearby irrigation farmers gathered for a demonstration to challenge the terms of the Albufeira Agreement. They argue that the conditions when the treaty was signed in 1998 do not reflect today’s realities, and there is concern that water might be used for power generation rather than for human consumption or irrigation.
For the Irrigation Communities Association this is a crucial point. They maintain that 80 percent of water should be reserved for human use and 20 percent for energy production. The worry is what will happen next year if insufficient water remains for crops. Herminio Medina, head of the Páramo Irrigators community, raised the question during a meeting with local government representatives and the head of the León Provincial Council. He underscored the disparity between savings and ongoing releases, stressing that water saved for irrigation should not be diverted to electricity.
Residents also note that some water is already routed through multiple stages before it reaches the sea, a process that incurs costs. Ángel González of the National Federation of Irrigation Communities expresses concern that water is redirected away from consumer needs and toward power generation. The conversation about water distribution has grown tense, with protest plans considering action at the Riaño reservoir in León. Yet the challenge remains that Spain cannot unilaterally alter an international treaty. Any modernization would require negotiations with Portugal.
Criticism for release
The two countries maintain cooperative relations and kicked off the year with an agreement to strengthen coordination. Still, many affected farmers want their grievances heard as climate change narrows water resources and the policy of prioritizing extractive needs endures. In a statement to La Opinion de Zamora, the Asaja agricultural organization criticized the current evacuation policy. It noted a sequence of releases from major reservoirs and warned that rivers in the Esla, including the Riaño and Porma, as well as the Ricobayo reservoir, are affected by the plan.