Water level in the Mullaperiyar dam receded to 141.17 ft on Sunday afternoon.
The inflow of water was 1005 cft per second and the discharge 2,100 cft per second, an official of the Tamil Nadu Public Works Department (PWD) said. The water level in the morning was 141.25 ft.
The water level decreased owing to high level of water discharge and reduced inflow into the reservoir.
The High Power Monitoring Committee appointed by the Supreme Court is scheduled to visit the dam on Monday to analyse the impact of rise in the water level to 142 ft.
The water level reached the maximum level early Friday. An official of the district control room at Painau said the State Disaster Management Force was camping in the district to take all precautionary measures.
A Tamil Nadu PWD official blocked the entry of a team led by Shekhar Kuriakose, Special Officer, State Disaster Management Force, into the dam stating that there was no official permission for the visit.
Meanwhile, Principal Chief Conservator of Forests V. Gopinath has collected details of the submerged areas of the Periyar Tiger Reserve (PTR) and its flora and fauna.
The State government plans to move the National Green Tribunal as the increase in the water level has adversely affected the ecosystem of the protected area.
An official of the PTR Hundreds of hectares of land had submerged, and the worst affected were the resident birds who had made nests on the tree stumps in the lake that were under water now. The rising waters had submerged elephant corridors too, he said.
The rise in the water level would also affect the tourism sector, as the sightings of the animals, including herbivores, had decreased, he said.