The situation caused by the drought in the Tagus and all the international rivers "should lead the governments of Spain and Portugal to align in a planning and management of river basins that establish real ecological flows", argues Zero, in a statement, taking stock of the flows of the three main Portuguese international rivers: Douro, Tagus and Guadiana.

"At the moment, the Hydrographic Region Management Plans for the period 2022-2027 are under public discussion and this is the right time for a discussion to be had between the two countries", stated the environmental association.

According to Zero's assessment, which used data from the National Water Resources Information System recorded up to the 3 September, there is a third of the volume of water missing in the Douro compared to what is established in the conventions.

"Spain had transferred 2,331 cubic hectometres of water since 1 October, 2021, when the annual flow is 3,500 cubic hectometres, thus lacking 1. 169 cubic hectometres, or about 33 percent of the total due," reads the document, in which the association warns that "as the flows of recent weeks have varied between 1.5 and 4.5 cubic hectometres per day and the weather situation has not changed substantially, it is obviously impossible to make up the missing volume of water.

In the Tagus, it is also "virtually certain" that Spain "will have to claim" the exception regime for failure to comply with the annual flow, according to the organisation, since in drought situations, it is expected that Spain may not deliver the flows to Portugal.

The data collected on 3 September for the flow inflow to the Fratel Dam showed that about 15 percent (393 cubic hectometres) of the fixed annual flow (2,700 cubic hectometres) was missing.

The Guadiana had been 20 days without reaching the minimum daily flow and 17 percent below the annual minimum at the beginning of September, with Spain invoking a situation of exception for not meeting the flow rates.

"Spain has to guarantee a daily average value of two cubic metres per second and from the 1 October 2021 until the 3 September, where there were 20 days when this did not happen. Once again, despite the huge capacity of the Alqueva reservoir, in the long term, an expansion of irrigation may be at risk with these restrictions associated with more frequent and extreme drought situations," Zero warns in the statement.

The assessment was made a few weeks before the end of the hydrological year, which runs from 1 October 2021 to 30 September 2022, based on the hydrometric stations provided for or equivalent in the Convention on Cooperation for the Protection and Sustainable Use of Water in Luso-Spanish Hydrographic Basins.