Stanley Reservoir, lifeline of Cauvery Delta in Tamil Nadu, steps into 90th year

As Tamil Nadu and Karnataka are on the verge of fighting yet another legal battle over sharing of Cauvery water, the Stanley Reservoir, a giant structure built during the British regime which still serves as the lifeline of lakhs of farmers in the Cauvery Delta region, quietly stepped into its 90th year on Monday.

It was on this day – August 21 – 89 years ago in 1934, the sluices of the reservoir in Mettur, 50 km from Salem in Tamil Nadu, built over a period of 10 years were opened for the first time. Named after Lt. Col. Sir George Frederick Stanley, who was the Governor of the then Madras State from 1929 to 1934, the reservoir is one of the largest dams in India having been constructed in a gorge, where the Cauvery River enters the plains.

From the day its gates were opened for the first time in 1934 to this date, the 89-year-old reservoir is the lifeline of farmers in the Cauvery Delta region who depend on water released from the dam for the cultivation of kuruvai (short-term) crops and preparations for samba crops.

Over the years, the designated date for opening the sluices of the reservoir was shifted to June 12, keeping in mind the arrival of the southwest monsoon that hits Kerala on May 31 and Karnataka a little later. However, the gates of the reservoir were not opened on the designated date of June 12 for over 60 times since the 1930s due to the non-availability of adequate water.

The dam’s storage depends on water released from reservoirs in Karnataka – while the Full Reservoir Level (FRL) is 120 feet, the total water storage is about 94 tmcft. The catchment area of the Cauvery River up to the dam site is 42,924 sq km, while the project consists of a masonry gravity dam of length 1614.4 m and height 65.23 m.

Kuruvai (short-term) crops entirely depend on water released from Mettur dam, while samba gets benefitted from the northwest monsoon that hits Tamil Nadu in October.

In the past few years, the dam has been attaining FRL quite a few times due to incessant rains in the catchment areas of River Cauvery in Karnataka. However, lack of adequate rains this year has brought the focus yet again on sharing of the Cauvery river water – while Karnataka says it doesn’t have enough water to release, Tamil Nadu contests the claim and points to imminent withering of kuruvai crops which has been cultivated in an area of about 5 lakh acres in the Delta.

Both states have now knocked at the doors of the Supreme Court with their known stands – TN wants water to be released according to the monthly schedule, and Karnataka says it cannot release it. The water dispute was settled amicably by the Supreme Court in 2018 when it modified the award of the Cauvery Water Disputes Tribunal (CWDT) and released a monthly water release schedule to Karnataka.