In recent weeks, the flow of the Tagus River in its middle section has visibly decreased. In Toledo, the flow of the river has dropped so much that it cannot overcome the Safont weir. Throughout the city there is only a succession of stagnant water that makes it difficult to maintain the ecological conditions of the river.

La situación es más grave aguas abajo, pasado el embalse de Castrejón, según se va acercando el río Tajo a Talavera de la Reina. En la estación del Sistema Automático de Información Hidrológica (SAIH) que la Confederación Hidrográfica del Tajo tiene en el municipio de Cebolla se están recogiendo unas caídas en el caudal alarmantes por debajo de los 3 m³/s. Esto equivale, en un río con una anchura de cauce como el Tajo, a que apenas circule el agua. A su paso por Talavera de la Reina, desde el 12 de junio, hay momentos en los que el caudal del río Tajo se sitúa por debajo de los 10 m³/s establecidos como caudal mínimo legal.

There is no justification to go below the legal minimum

El artículo 59 de la Ley de Aguas confiere a los caudales ecológicos prioridad por encima de      todos los demás usos. Es decir, se deben respetar en cualquier circunstancia, salvo por cuestiones excepcionales de escasez de agua para abastecimiento humano.

Pese a que los caudales mínimos en Aranjuez, Toledo y Talavera están derogados por las sentencias del Tribunal Supremo (TS) de 2019, no deben circular caudales por debajo de ese mínimo, ya que el TS consideró esos caudales insuficientes para garantizar los objetivos ambientales del río Tajo. Es lógico, por tanto, que, hasta el establecimiento definitivo de nuevos caudales ecológicos más ambiciosos, estos no puedan ser menores de 10 m³/s en Talavera de la Reina.

Why has this anomalous situation occurred?

The alarming decrease in the water level that we observed these weeks is due to an insufficient release of water from the Entrepeñas and Buendía reservoirs, upstream. The discharges from the headwaters must be used to satisfy all the needs of the Tagus, including irrigation, which is more abundant at this time of year. Although there is a monthly limit on the amount of water that can be released from the headwaters to the Tagus itself, set in the Memorandum, in the Rules for Exploitation of the Tagus-Segura Transfer, managers can exceed it due to environmental requirements with due justification.

During the summer months there is an increase in agricultural demands in the middle zone of the basin which, due to the priority of the transferring basin, must be satisfied. These agricultural demands are included in the hydrological planning and, therefore, are adapted to the amount of existing resource, always taking into account compliance with the minimum flows. Regardless of whether an evaluation is pending on the efficiency of these irrigations or whether the extension of the irrigated surface is the most sustainable for the good condition of the Tagus River, at this time the minimum flows are not being guaranteed. The decreases in flow to which the river is being subjected in its middle section are incompatible with the maintenance of river fauna and vegetation. The Tagus River is slowly being exhausted and it is not because its basin lacks natural contributions.

Paradoxically, the Exploitation Rules of the Tagus-Segura transfer define the waters that are derived from its headwaters to the Segura as surplus from the Tagus. This makes no sense, given that the discharges that are being produced from Entrepeñas and Buendía to the Tagus are not sufficient to meet the basic environmental demands of the Tagus River itself in the Talavera de la Reina area, which are a priority over those of the rest of the region. applications. It is necessary, at a minimum, to modify the Operating Rules of the Tagus-Segura transfer with regard to the maximum discharges to the Tagus. It is the only river in Spain that has a limit by law on the amount of water that can circulate through it.

In short, there is no justified reason for the flows in the Tagus River to fall below the established legal minimum.

(Foto de la entrada: Río Tajo a  su paso por Talavera de la Reina, junio de 2022. La vegetación invade el cauce al discurrir sin apenas caudal)