In a statement, the APA said that on the last day of August, compared to the previous month, there was a decrease in 12 of the monitored river basins and an increase in one (Vouga).

The Mira and Ribeiras do Barlavento basins continue with total storage values ​​lower than the historical average values.

The APA indicates that the number of reservoirs with water availability above 80%, compared to the previous month, decreased from 16 to 11 and the number of reservoirs with water availability below 40 percent rose to eight (one in the Mondego basin, five in the basin do Sado and two in the Algarve).

The reservoirs assessed on August 31, which present total volumes below 40%, corresponding to about 8% of the universe of reservoirs assessed, are: one in Mondego, in Fronhas, (39%), five in the Sado basin, in Monte da Rocha (20%), Campilhas (8%), Fonte Cerne (26%), Roxo (19%) and Odivelas (39%), one in the Barlavento basin, in Bravura (20%) and one in the Arade basin (33%).

The Santa Clara reservoir, in the Mira basin, is at 45%, below the minimum level for exploration without using pumping.

The August 2021 storages by watershed are higher than the August storage averages (1990/91 to 2019/20), except for the Lima basins.

Each hydrographic basin can correspond to more than one reservoir.