Controversy
The document gives the level of water on crucial dates to back its claim that the floods in Kerala was not a result of water discharged from Mullaperiyar.

The Tamil Nadu government on Friday categorically denied the allegations of mismanagement raised by the Kerala government in the operation of Mullaperiyar dam and filed a counter affidavit in the Supreme Court to the same effect. This was in response to the affidavit filed by the government of Kerala stating that the sudden release of water from Mullaperiyar caused flooding in the region.

The TN government, represented by M Selvaraju who is a member of the Inter-state Waters Wing, Water Resources Department, Tamil  Nadu, submitted to the apex court that the state is fully committed to the safety of people living downstream of the dam and that all possible steps are being taken to safeguard the interests of both Tamil Nadu and Kerala.

Stating that the Mullaperiyar dam was constructed, operated and maintained by Tamil Nadu, the affidavit said that the water from the dam is used to meet the irrigational and drinking water needs of drought-prone areas in five districts in Tamil Nadu -- Theni, Madurai, Ramanathapuram, Sivagangai and Dindigul. The document further stated that Kerala maintained three reservoirs and one barrage in the Periyar basin apart from Mullaperiyar.

“I state that Idukki Dam located about 40 KM downstream of Mullai Periyar Dam has an independent catchment area of 649 sq. km. which is a hilly terrain. It received heavy rainfall during July and August, 2018 and the inflow into Idukki dam was heavy, in the range of 84.28 Mcm (126.63 MU), and Kerala released water from Idukki Dam from 10.08.2018 onwards. Similarly, other major Dams in the State of Kerala received heavy to very heavy rainfall during the current monsoon season, beginning from June, 2018 resulting in heavy overflows in many Dams of Kerala,” read the affidavit.

Further, Tamil Nadu submitted before the Dam Safety Organisation that the Chief Engineer of Central Water Commission, who is the Chairman of the Supervisory Committee, along with the members of the two states inspected the Mullaperiyar dam on August 4 and found the overall condition of the dam and its appurtenant structures satisfactory. It also stated that the Chairman of the Sub Committee under the Supervisory Committee inspected the dam on August 15 and found everything in order.

“I state that the water level in the Idukki Dam on August 14 was 731.08 m (2399 ft.) against the Full Reservoir Level (FRL) 732.43 m (2403 ft.) and the quantity spilled was 46.26 Mm3 (1.634 TMC). But on August 15 the level was 731.868 m (2401 ft.) and the quantity spilled was 390.51Mm3 (13.791 TMC), which is evident from data available in the website of KSEB. Thus it can be seen that State of Kerala suddenly increased the releases from 46.26 Mm3 on August 14 to 390.51 Mm3 on August 15. Similarly, the release of water from Idamalaiyar dam, which flows into the lower part of Periyar river was 117.72 Mm3 on August 16 while the release from the dam was Nil on August 14 and August 15, and thus, the release was sudden,” read the affidavit.

Further stating that the water released from Mullaperiyar was not the reason for flooding of the region, the document said, “The storage level in the Mullai Periyar Dam as on June 1 was 115.70 ft. and on August 14 at 8.00 A.M was only 136.1 ft. against the permitted storage level of 142 ft. The inflow was only 4419 cusecs with a diversion of 2200 cusecs through the tunnel to Tamil Nadu. On August 15, when the water level reached 140 ft., spilling of water to downstream of the dam commenced and the initial release was 4489 cusecs. This was gradually stepped up in the course of the day to 8905 cusecs and the average spilling was 14429 cusecs. On August 15 morning the level rose to 140.7 ft. and the inflow was 16629 cusecs and the quantity spilled to Idukki Dam was only 14429 cusecs (1.247 TMC),  whereas the outflow from Idukki Dam on the same day was 390.51 Mm3 or 13.79 TMC. On August 16, inflow into Mullai Periyar Dam was 25,730 cusecs and the quantity spilled to Idukki Dam was 23,397 cusecs i.e., 2.022 TMC and the outflow from Idukki Dam was 126.63 Mm3 (4.472 TMC). Similarly on August 17, 18 and 19, Idukki Dam surplused 114.84 Mm3, 70.52 Mm3 & 59.4 Mm3 respectively. Thus, the total quantity spilled from Idukki Dam from August 14 to 19, 2018 is 808.16Mm3 (28.54 TMC), and from Idamalaiyar dam in the corresponding period is 219 Mm3 (7.74 TMC) totaling to 1027.16 Mm3 (36.28 TMC), whereas the quantity released from Mullai Periyar Dam to Idukki Dam during the corresponding period is far less than the quantity surplused from Idukki and Idamalaiyar dams. Thus, it is seen that that flood surplus from the Idukki dam is mainly due to the flows generated from its own independent catchment due to unprecedented heavy rainfall while the contribution from Mullai Periyar Dam was significantly less.”

Claiming that the lower Periyar basin also receives the surplus waters from Idamalaiyar Reservoir, Bhuthathankettu Reservoir, etc., in Kerala, which contributed to the flooding of lower Periyar area, the TN government submitted that the spillage from Mullaperiyar Dam is far less when compared to the total surplus flow from the Idukki, Idamalaiyar and other tributaries of the Periyar basin.

The TN government also mentioned that the water released from Mullaperiyar dam could have been reduced to a large extent if the Kerala government had permitted the completion of strengthening works in the dam to hold water up to 155 ft as certified by an expert committee and accepted by the Supreme Court in 2014.

Kerala had earlier submitted an affidavit in the Supreme Court alleging that the officials from Tamil Nadu did not cooperate with them and the water released from Mullaperiyar was the reason for flooding in the region. They had alleged that despite multiple requests from the Kerala government to TN to reduce the water level in the dam, TN did not heed to their requests.

TN’s affidavit stated that enough warnings were given by the TN officials to the officials of the Kerala government from the moment water crossed the level of 136 ft in the Mullaperiyar dam.