On the last day of October and compared to the previous month, there was an increase in the volume stored in two river basins and a decrease in 10.

The data indicates that the Barlavento basin was the one with the lowest water availability at the end of October (13.9%).

The Lima (23.4%), Ave (35.9%), Sado (40.8%) and Mira (42.7%) basins also had lower water availability at the end of October.

According to SNIRH data, the Guadiana (75.6%), Mondego (67.5%), Douro (67.2%), West (63.8%), Tagus (60.4%), Cávado ( 58.9%) and Arade (56.5%) had the highest levels of storage at the end of October.

The October 2021 storages by watershed are lower than the October storage averages (1990/91 to 2020/21), except for the Douro, Mondego, Ribeiras do Oeste, Guadiana and Arade basins.

Each hydrographic basin can correspond to more than one reservoir.