September storages by river basin were, however, higher than average, with the exception of the Sado, Mira, Guadiana, Arade and Barlavento basins. The Barlavento basin continues to be the one with the smallest amount of water, just 7.7%, when the average is 54%.

Of the 60 monitored reservoirs, 10 had water availability greater than 80% of the total volume and 19 less than 40%.

According to the SNIRH data available today, the basins with the lowest water levels at the end of September were Barlavento (7.7%), Arade (26.7%), Mira (31.2%), Sado (36.2%), Ave ( 51.8%) and Oste (53.5%).

The Douro basin had the largest volume of water, with 77.2% of its capacity, followed by the Cávado (77.1%), Lima (75.1%), Tagus (68.2%), Guadiana (66.2%) and Mondego (63.6%).

September 2023 storages by river basin were generally higher than the September storage averages (1990/91 to 2021/22), except for the Sado, Guadiana, Mira, Ribeiras do Algarve and Arade basins.

Each river basin may correspond to more than one reservoir.