Mullaperiyar dam level at 116.75 ft, well below the 142-ft ceiling

The water level in the Mullaperiyar dam stood at 116.75 feet on Saturday, with an inflow of 718 cusecs and a discharge of 400 cusecs. The maximum permissible level for the reservoir is 142 feet, leaving more than 25 feet of headroom.

The dam lies in Kerala's Idukki district but is operated by Tamil Nadu under an 1886 lease agreement. It is the principal source of water for irrigation and drinking needs in Theni, Dindigul, Madurai, Sivaganga and Ramanathapuram districts. The 142-foot upper limit was settled after years of litigation between Kerala, which has raised safety concerns about the century-old structure, and Tamil Nadu, which depends on the reservoir for its farming economy.

At the Vaigai dam, the level was 43.77 feet against a full level of 71 feet, with an inflow of 696 cusecs and a discharge of 86 cusecs. The combined storage in the Periyar credit was 3,023.34 mcft.

For readers unfamiliar with the terms used in reservoir bulletins: a cusec is one cubic foot of water flowing per second, and mcft stands for million cubic feet. The Periyar credit refers to Tamil Nadu's share of water accounted for in the Periyar system, which feeds the Mullaperiyar and downstream dams.

Rainfall recorded in the 24 hours ending at 6 a.m. on Saturday, in millimetres, was: Maruthanadhi dam 15.4, Uthamapalayam 4.8, Peranai 2.8, Kodaikanal 2.6, Veerapandi 2.2, Thekkadi and Shanmuganadhi 0.8 each, Gudalur 0.6, Periyar 0.6 and Madurai 0.4.

Maruthanadhi dam recorded the highest rainfall in the region during the period, followed by Uthamapalayam. Kodaikanal, which lies in the catchment area of the Periyar system, received 2.6 mm, while Madurai recorded the least at 0.4 mm.

At Mullaperiyar, the inflow of 718 cusecs is higher than the discharge of 400 cusecs, which means water is being retained in the reservoir and the level will rise as long as inflows continue at this rate. Even so, the reservoir remains far below its permitted ceiling, and the present level is not in itself a cause for concern on storage grounds.

Reservoir levels in this part of the Western Ghats are shaped by the south-west monsoon, which brings heavy rain to the catchment between June and September, and by the north-east monsoon, which contributes through October and December. Daily gauge readings are released as part of routine monitoring so that farmers, downstream residents and district administrations can plan releases and drawdowns.

The Vaigai dam, which irrigates a large part of the southern districts, is also at less than two-thirds of its capacity, with inflow of 696 cusecs exceeding discharge of 86 cusecs. The gap between inflow and outflow at both reservoirs indicates that storage across the system is building up gradually rather than being drawn down.

This report is based on the official gauge readings for the day and does not include any forecast of levels for the coming week.