Mullaperiyar water release: Tamil Nadu shares details with Supreme Court

Counters Kerala’s charge that sudden discharge led to floods.

Updated - November 28, 2021 08:25 am IST

Published - August 25, 2018 09:46 pm IST - NEW DELHI

The Mullaperiyar Dam in Idukki district of Kerala.

The Mullaperiyar Dam in Idukki district of Kerala.

Countering Kerala’s version in the Supreme Court that sudden water releases from the Mullaperiyar dam into the Idukki and Idamalayar dams downstream led to the deluge, Tamil Nadu presented statistics of its controlled and gradual water release on the crucial days of August 15 and 16, when the Mullaperiyar dam’s water level overshot the 140 feet mark.

Water spilled from the Mullaperiyar reservoir to the Idukki dam was only 1.247 tmc on August 15 morning, when the water level rose to 140.7 feet against the permissible limit of 142 feet.

The next day, on August 16, Tamil Nadu again released 2.022 tmc of water from the Mullperiyar dam to the Idukki dam. The total spillage from the Mullaperiyar dam between August 15 and 16 was 3.269 tmc.


On the other hand, the total spillage of surplus water from the Idukki and Idamalyar dams from August 14 to 19 added up to 36.28 tmc, Tamil Nadu informed the Supreme Court.

Tamil Nadu took the court through the series of events that transpired from August 14.

It said inflow into the Idukki dam, located about 40 km downstream of the Mullaperiyar dam with an independent catchment area of 649 sq km, was heavy, with rains lashing Kerala since July. Kerala had been releasing water from the Idukki dam since August 10. The Idukki reservoir alone had spilled 39.10 tmc in 12 days from August 10 to August 21.


On August 14, the water level in the Idukki dam was already 731.08 m against the dam’s full reservoir level of 732.43 m. The spillage from the Idukki dam that day was 1.634 tmc. The very next day saw a sudden increase in spillage from the Idukki dam — from 1.634 tmc to 13.791 tmc.

Kerala also released 117.72 Mm3 of water into the lower Periyar basin all of a sudden from the Idamalyar dam on August 16. This was after no spillage for preceding two days — August 14 and 15.

Compared to the sudden releases of water from the Idukki and Idamalayar dams, Tamil Nadu said it began spillage to downstream from the Mullaperiyar dam only after water level rose to 140 feet on August 15. It initially released 4,489 cusecs and gradually stepped it up to 8,905 cusecs. When water rose to 140.7 feet, controlled spillage to the Idukki dam was still 1.247 tmc. On the other hand, Idukki dam had spilled 13.79 tmc the same day.

On August 16, Tamil Nadu said the inflow to the Mullaperiyar dam was as high as 25,730 cusecs, yet it spilled only 2.022 tmc to the Idukki dam. However, the spillage from the Idukki dam that day was 4.472 tmc.

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