Spill gates of the Laxapana Reservoir have been opened due to heavy rainfall in catchment areas.
The Nuwara Eliya Disaster Management Centre said three spill gates were opened since yesterday.
The Norton Bridge-Wimalasurendra Reservoir has also begun spilling over.
NewsRadio area correspondent said water levels of the Castlereagh and Maussakelle reservoirs are approaching spill levels due to incessant rain.
Engineers of the Canyon, Laxapana, New Laxapana, Polpitiya and Wimalasurendra power stations said power is being generated at maximum capacity due to rising water levels.