Mullaperiyar dam structurally, seismically safe; no limits specified for life of a dam: Tamil Nadu to Supreme Court

The Mullaperiyar dam situated in Kerala's Periyar river and which supplies water to five districts of Tamil Nadu, is structurally, hydrologically and seismically safe, the State of Tamil Nadu has informed the Supreme Court (Dr. Joe Joseph v. State of Tamil Nadu). .The Kerala government is raising the issue of dam safety in a bid to prevent the water in the dam's reservoir from being raise to 142 feet as mandated by the Supreme Court's 2014 judgment, a reply affidavit filed by Tami Nadu before the top court said. "The repeated assertion of Kerala and Petitioners from Kerala in Writ Petitions filed from time to time inter-alia seek decommissioning of the existing dam and construction of a new dam, which is wholly impermissible in the light of judgment of this Hon’ble Court on the safety of the dam. The dam has been found to be hydrologically, structurally and seismically safe," the affidavit said..Pertinently, in response to the argument by Kerala about the age of the dam which is 126-years-old, the Tamil Nadu government, placing reliance on the 2012 Empowered Committee report, has said that there are no limits, specified for the life of a dam."On the life of the dam, the Empowered Committee has stated that the dam’s life is linked to the inherent health and care through maintenance, repair and rehabilitation. There is no limits, specified for the life of a dam," the affidavit said.The affidavit came in response to Kerala government's argument that the 126-year-old dam is structurally unsafe and should be decommissioned and a new dam constructed.The Kerala government had told the Supreme Court that any failure of the Mullaperiyar Dam could have a cascading effect on the Idukki Dam situated downstream, and that the combined failure of the two dams will have a catastrophic impact on the lives and properties of 50 lakh people.The State of Kerala had also submitted that in the past few years, erratic rainfall patterns caused due to climate change have led to instances of sudden spikes in the water levels of the Dam's reservoir.Kerala government's affidavit setting out these argument was filed in a plea to ensure that the water level in the Dam's reservoir is not allowed to exceed 139 feet, three feet below the permissible limit of 142 feet prescribed by the 2014 judgment of the top court.In its 2014 judgment, the Supreme Court had ruled in favour of Tamil Nadu and held that the dam is safe but the water level in the dam should be kept at 142 feet. Later during the Kerala floods of 2018, a petition came to be filed before the top court in which an interim order to maintain the water level at 139 feet during the Kerala floods was passed as a temporary arrangement.The Kerala government in its present plea (which has been filed as an application in a 2020 writ petition by one Dr. Joe Joseph on dam safety) has asked for a similar direction in view of the incessant rains in the State which has led to a rise in the water level of the reservoir..When the matter was heard on October 25, 2021 the Court had observed that the issue surrounding fixing of maximum water level was a serious one, but was not something which the Court can decide upon, since it lacks the expertise for the same.A Bench of Justices AM Khanwilkar and CT Ravikumar, had therefore, said that it is the task of the expert supervisory committee appointed by the Court to decide the same. It asked the committee to take a call expeditiously after discussing with all parties concerned.Pursuant to that, the expert committee had met and suggested that no change in water level is required.The Kerala government had, however, dissented and filed a note setting out its concerns. Subsequently, it had filed a detailed affidavit seeking decommissioning of the dam. .The Tamil Nadu government, in is reply affidavit has given a para wise rebuttal of Kerala's affidavit. Some other aspects contended by Tamil Nadu are as follows:.On Strengthening of baby dam Tamil Nadu has alleged that State of Kerala had all along been obstructing the implementation of the balance strengthening works in baby dam and earth dam by not permitting to cut the trees in the downstream of baby dam and by not repairing the ghat road which is the only land route to the dam site.The supervisory committee constituted as per Supreme Court's 2014 judgment had recommended further strengthening measures to the Baby dam.Cutting of trees for enabling strengthening of baby dam was not permitted by Kerala inspite of repeated direction of the supervisory committee. At a meeting held on October 26, 2021, State of Kerala (eventually) agreed to expedite all pending forest clearance for maintenance of approach road, and carrying out the balance strengthening works. "The State of Kerala issued a letter dated November 6, 2021 permitting the cutting of trees in furtherance of the decision of the supervisory committee," the affidavit said..On erratic rainfall patternIn response to Kerala government's argument that erratic rainfall levels have caused sudden spike in water levels in the dam, the Tamil Nadu government has submitted that no concrete details have been furnished."The Respondent is wantonly exaggerating the safety issue, by referring to flood issues elsewhere, which are not at all relevant to Mullai Periyar Dam," the affidavit said.Besides, the catchment area of Mullaperiyar dam lies in rain shadow area."The average annual rainfall in the catchment of Idukki dam is 3310 mm. he annual rainfall at Mullai Periyar dam site is only 2080 mm. The rainfall in the catchment of Idukki dam is much higher than that of Mullai Periyar dam catchment. Thus the statement that filling up of Mullai Periyar Dam would be faster is incorrect and denied," it was submitted.Further, the statement on the annual average rainfall of Mullai Periyar catchment referring to the rainfall of the stations, namely Mullai Periyar dam and the Thekkady are not relevant, since these rainfall stations are at the end of the catchment of Mullai Periyar dam. They are not representing the catchment of the dam, the affidavit added..Reference to Uttarakhand flood not relevantThe Tamil Nadu government submitted that reference to disaster that occurred due to the Uttarakhand flood is not relevant to Mullaperiyar dam, since Mullaperiyar dam is falls in seismic Zone III and Uttarakhand falls in Zone IV & V. This issue was also raised by State of Kerala before the Empowered Committee which did not agree to the same. The State of Kerala is misleading the Court and exaggerating this issue, it was alleged..On Rule Curve.Importantly, the Tamil Nadu government submitted that the Supreme Court is only considering the issue of rule curve to be followed and the gate operation schedule. The Central Water Commission (CWC) had asked Tamil Nadu to prepare the rule curve and gate operation schedule based on the historical data which were compiled by the State of Tamil Nadu as per the direction of the CWC."State of Tamil Nadu submitted its rule curve on January 29, 2021 to CWC wherein the Upper Rule 15 Level was from 137.44 on 10th June and thereafter increases to 142 ft. on 20th September. However, this was modified by CWC lowering the initial Upper Rule Level to 136 ft," the affidavit said.Though the Court was considering only the aspect of rule curve State of Kerala in its reply filed on November 9 ,2021, has enlarged the scope and raised various issues which have been settled by the two judgments of the Supreme Court in 2006 and 2014, Tamil Nadu contended."In the light of the above, this Court may be pleased to accept the Status Report filed by the CWC on the three aspects raised in the Writ Petition viz Gate Operation Schedule, Rule Curve and instrumentation and dispose of the Writ Petition," the Tamil Nadu government prayed.