All river basins fuller at end of December By TPN/Lusa, in News · 06-01-2021 16:00:00 · 0 Comments seventeen of the 59 reservoirs monitored had water availability above 80% of the total volume, while 14 had values below 40% All hydrographic basins monitored in Portugal registered increases in the amount of water stored on the last day of December, compared to the previous month, according to data from the National Water Resources Information System (SNIRH). At the end of December, seventeen of the 59 reservoirs monitored had water availability above 80% of the total volume, while 14 had values below 40%.