On the last day of December, compared with 30 November, there had been an increase in the volume stored in six monitored watersheds and a decrease in another six, according to data released on Friday by the SNIRH.
Of the 60 monitored reservoirs, 11 had water availability above 80 percent of total volume and 11 had availability of less than 40 percent.
The Ave was the river basin with the highest water availability (83.8 percent), followed by the Guadiana (79.1 percent), Mondego (66 percent), Douro (64.7 percent), Cávado (62.5 percent), Tejo (61 percent), Mira (59 percent), Barlavento (58.5 percent), Oeste (55.9 percent) and Arade (55.4 percent).
The Lima basin had the lowest levels in late December (26.8 percent).
The amount stored per watershed was below the average for December (1990/91 to 2017/18), except for in the basins of the Ave, Guadiana and Arade.
Each hydrographic basin may correspond to more than one reservoir.