Mettur Dam and the Stanley Reservoir: The Kaveri’s Great Wall in Salem

Where the Kaveri leaves the hills of Karnataka and gathers itself before the long run down to the sea, a grey wall of masonry closes the gorge. This is Mettur Dam, in the north-west of Salem district, one of the oldest and largest dams of its kind in India. Behind it lies the Stanley Reservoir, a broad sheet of water ringed by low forested hills. For the farmers of the far-off Kaveri delta, what happens at this wall each June is a matter of the whole year’s harvest.

A masonry wall across the Kaveri

Construction of Mettur Dam began in the mid-1920s and the dam was completed in 1934, after roughly nine years of work by a very large labour force. It is a masonry gravity dam — a wall heavy enough to hold the river back by its own weight — reported to stand about 37 metres (120 feet) high and to run some 1,700 metres (about 5,600 feet) along its crest. When it was finished it was often described as one of the largest dams in the world of its day, and it remains among the biggest masonry dams in India.

The dam was built to a single, ambitious purpose: to capture the monsoon flow of the Kaveri and release it in a controlled way through the dry months. Below the wall the river continues its course, and the view of the Kaveri escaping the dam is one of the things most visitors come to see.

The Stanley Reservoir

The lake that fills behind the wall is the Stanley Reservoir, named after Sir George Frederick Stanley, who was Governor of Madras in the years the dam was completed. Fed by the Kaveri and smaller streams that join above it, the reservoir is usually cited as having a capacity of around 93 thousand million cubic feet (tmc ft), though its effective storage is understood to have fallen over the decades as silt has settled behind the dam. The creation of the reservoir submerged land and at least a couple of villages, whose residents were resettled at Mettur.

When it is full, the reservoir spreads across the valley in a way that is best appreciated from the hill roads that climb above the town. The water, the surrounding hills and the dam together make Mettur a modest but genuine destination in its own right, quite apart from its working role.

Water, power and the delta

Mettur does three jobs at once. It stores irrigation water for the Kaveri delta far downstream; it generates hydro-electricity, through power houses at the dam and further down the river that together add up to a substantial installed capacity; and its stored water supports the coal-fired Mettur Thermal Power Station nearby, one of the larger thermal stations in Tamil Nadu. Together these make Mettur an important node in the state’s power and water map.

The single most watched event here is the annual opening of the dam for the delta’s kuruvai (short-term) paddy crop. By long custom the reservoir is opened around 12 June, a date chosen to coincide with the expected arrival of the monsoon in the Kaveri’s upper catchment. Because the Kaveri is shared between Karnataka and Tamil Nadu, and because the amount reaching Mettur depends on upstream rainfall and releases, the opening does not happen on the customary date in every year — in several recent years low storage delayed or prevented it. The distribution of Kaveri water between the two states is governed by a long-running framework of tribunal awards and subsequent orders; at Mettur that framework is felt very directly, in how much water is in the reservoir and when the gates can be opened.

The town and nearby Salem

Mettur grew up around the dam and its industries, and the town has a laid-out park, viewpoints and a bridge from which the dam can be seen. It makes an easy day trip from Salem city, about 50 kilometres away. Salem itself repays a stop: in the heart of the city, Mookaneri Lake is a restored waterbody with a walking path and boating, a pleasant contrast to Mettur’s working reservoir. Beyond the city rise the Shevaroy Hills, with the hill station of Yercaud and its own lake and viewpoints, so a trip built around Mettur can widen easily into a fuller Salem itinerary.

Visiting

The reservoir is at its most photogenic after the south-west monsoon, roughly August to October, when the water is high and the hills are green; the pre-monsoon months can find the lake drawn well down. Mettur is comfortably reached from Salem by bus or train, and the dam, park and viewpoints can be seen in a half-day. Keep in mind that the dam is a live piece of infrastructure — photography near the wall and the power installations may be restricted, so watch for signs and follow staff instructions. For more places like this, and for the wider region around it, see /india/tamil-nadu/guides/dams-and-reservoirs-of-tamil-nadu and /india/tamil-nadu/guides/salem-city-guide .