Water reserves (hydraulic stock) are associated with reservoir-type hydropower plants that take a long time to fill and are managed seasonally. Reserves decline in winter, when these plants run often, and are then restored in spring, when the snow is melting.
Rainfall conditions were good in 2018, so water reserves were high at the start of January 2019. Reserves were close to the 2018 level early in February, but subsequently remained higher than a year earlier as reservoir plants are not heavily used until the spring. It took longer to restore reserves than in 2018, but they exceeded the year-earlier level by September and were 30% higher at the end of the year, when precipitation is significant.