The state government has exempted information related to Mullaperiyar dam lease deed from the ambit of the Right to Information (RTI) Act. The General Administration department has invoked relevant sections of the RTI Act to exempt providing information about the original records of Mullaperiyar Dam Lease deed agreements, including sketches, blueprints, photos, etc., accompanying the original contract. 

The notification issued by Secretary K Biju cited that giving information on original records would prejudicially affect the security interest of the state.

As per clause (a) of sub-section (1) of Section 8 of the RTI Act, there shall be no obligation to give any citizen, information, disclosure of which would prejudicially affect the sovereignty and integrity of India, the security, strategic, scientific or economic interests of the state, relation with foreign state or lead to incitement of an offence. 

A lease indenture for 999 years was made in 1886 between Maharaja of Travancore and Secretary of State for India for Periyar irrigation works. By another agreement in 1970, Tamil Nadu was permitted to generate power also. The Mullaperiyar Dam was constructed during 1887-1895. Its full reservoir level is 152 ft and it provides water through a tunnel to Vaigai basin in Tamil Nadu for irrigation benefits in 68558 ha, according to the document published by the Ministry of Jal Shakti.

In 2024,, Union Minister of State for Environment, Forest and Climate change, Kirti Vardhan Singh told the parliament that the Ministry received a proposal on Parivesh portal in May 2024 for grant of Terms of Reference (ToR) for conducting Environmental Impact Assessment (EIA) study for proposed new Mullaperiyar Dam in an area of 39 ha located in Idukki by the Irrigation Design & Research Board (IDRB). In view of inter-state issues raised by the Government of Tamil Nadu, the Ministry sought the opinion of Central Water Commission (CWC), Ministry of Jal Shakti. The CWC, 

has informed that the Supreme Court constituted an Empowered Committee in 2010 to assess the safety aspects of Mullaperiyar dam. 

In the order of the Supreme Court issued in 2019 it was stated that the question as to whether any study could at all be carried out or not can always be considered and the move on the part of the state of Kerala can be questioned in case the respondents make any application to the SC court for any such permission, according to the reply.

The Central Water Commission had responded to an RTI application that the Periyar lake lease agreement is available in a CWC publication titled Legal Instruments on Rivers in India.