A sluice gate of the Upper Kotmale Reservoir has been opened following increased rainfall in catchment areas, the Department of Irrigation noted.
Engineers stated the move was necessary to maintain normal water levels.
Water is also being released from several major reservoirs, including Nachchaduwa, Rajanganaya, Deduru Oya, Lunugamvehera, Weheragala and Senanayake Samudraya, though officials noted this will not affect downstream areas.
The department has activated its 24-hour operations room to monitor conditions, while urging the public to remain alert as monsoon rains intensify.