One spill gate of the Upper Kotmale Reservoir remains open due to continued rainfall in its catchment areas, reservoir engineers have stated.The spill gate was opened following rainfall in the catchment areas and remains open as rain continues to affect the region.Reservoir engineers have warned that the remaining spill gates could open automatically if heavy rainfall continues in the catchment areas.Residents living on both sides of the Kotmale Oya, downstream of the reservoir dam, have therefore been urged to remain vigilant and exercise caution.