The Public Works Department (PWD) officials said that the water level in the dam reached its FRL of 120 feet at 6.15 am on Wednesday.
The dam last crossed its FRL on September 7, when up to 70,000 cusecs was released from the dam, resulting in flooding in several downstream areas of the Cauvery. The inflow into the dam then began to come down gradually, only to rise up again to reach its full reservoir level on September 24 due to heavy inflow following good rains in the Cauvery catchments.
Thereafter, the rains receded causing a significant drop in the inflow into the dam. On October 17, the dam storage level dipped to 113.03 feet as the quantum released from the dam surpassed water flowing into it.
However, with the onset of the northeast monsoon, rains resumed in the catchment areas in Karnataka, thereby increasing the inflow into the dam over the past one week.
While the inflow surged, the discharge from the dam was maintained at a low 500 cusecs on Tuesday as water requirements for delta irrigation were met out by the heavy rains pounding Tamil Nadu.
On Tuesday, around 8 am, the dam level rose to 118.600 feet and touched the FRL on Wednesday morning. As the inflow into the dam stood at 25,000 cusecs, the discharge from the dam was increased to 27,000 cusecs.
In view of heavy inflow into Mettur, a flood alert has been issued to as many as 12 districts in downstream Cauvery basin.
Due to flooding in the Cauvery, people were advised against entering the water to bathe or for other purposes.
Police and rescue personnel have also stepped up vigil along the course of the river as a precautionary measure.