On 19th January 2026, the foundation stone for the construction of the Mamallan reservoir was laid by M K Stalin, the then-Chief Minister of Tamil Nadu. This reservoir will supply drinking water to the city of Chennai.
The reservoir will be built on land that is currently labelled 'Great Salt Water lake' in Google Maps, and is also referred to as Kovalam estuary. It is a tidal marshland, where sea water meets fresh water. For most of the year, it is a patchwork of water bodies whose shapes shift with the daily tide. In the monsoon the water bodies merge into a swollen whole, one with the sea. These water bodies are referred to as aaru (river) by the locals. Prawns, crabs and fish thrive here, and it is a rich inland fishing ground.
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| Inland fishing boats in the Kovalam estuary. (June 2026) |
The Mamallan reservoir will cover this tidal marsh with a fresh water reservoir. Bunds will be built to keep the sea water out.
The prawns, crabs and fish species caught in this area require both the estuary and the sea for their survival. The juveniles of prawns and crabs live in the estuary, and the adults live in the sea. Mullet fish live in the estuary, but spawn in the sea. Obstructing the mixing of freshwater and seawater will severely impact the populations of these species in the area, and as a result, wipe out the livelihood of inland fisherfolk.
Sixteen fishing villages will be affected by the reservoir. Narayanan, a fisherman and community leader from Kovalam, was one of the first among the village locals to hear about the reservoir. He was told about it by Saravanan, a long-time fisherman activist in Chennai. The local fishermen had not been informed, let alone consulted, about the project before it was announced.
Narayanan has been leading the campaign against the Mamallan project. “This project will destroy one of the last remaining high yielding fishing grounds in and around Chennai. It will be a huge setback for the fishing community”, he says.
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| Narayanan (left) with a fisherman in the Kovalam fish market |
Suresh
Suresh, from Kovalam, is an inland fisherman whose livelihood will be severely affected if the reservoir is built. He fishes in the aaru all year round, earning about 1000 rupees a day, which is just enough to sustain his family. Suresh catches prawns, crabs and madava meen (mullet fish), using a different net for each of them.
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| Suresh on his inland fishing boat in the Kovalam estuary. (June 2026) |
Suresh has been fishing since he was ten years old. Initially he accompanied others. For a while he worked on a friend’s sea fishing boat, getting a share in the catch. Finally he bought his own inland fishing boat, which costs around 50 thousand rupees, and since then he has been fishing in the aaru.
An inland fishing boat is much cheaper than a sea fishing boat which costs 5 lakh rupees, thus providing a more accessible source of livelihood. Fish caught in the estuary are cheaper than sea fish, and are very popular among the large migrant worker population who live in the area, who often cannot afford sea fish.
“If the reservoir comes up, there will be no more prawns or fish here”, says Suresh. Even the prawns caught in the sea mature in the aaru before they go into the sea”, he says. “It is not just fisherfolk, even the birds will be affected. They come for the fish. I have seen so many different kinds of birds when I fish here in the aaru.”
Suresh has been assisting Narayanan with the campaign against the reservoir. When I went to Kovalam, he showed me where they fished, explained the problems they faced, and the dangers posed by the Mamallan project.
The illegal mud block
Some days after the foundation stone for the project was laid, Suresh on his morning fishing round, found that a channel connecting fresh water and salt water had been blocked off with mud. Only a very small part of the channel had been left open. He said that this has been done to dry off the area so that JCBs can be driven there. The waters near the mud blockage had been the best fishing spot for many local fishermen. After the block came up, fishermen found that there was barely any catch in that spot. Since then Suresh has been fishing at a different spot with lower yields. The mud block came up although the project has not yet received environmental clearance.
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| The pile of mud in the foreground blocks the path of the water, leaving just a small channel open. (July 2026) |
Pollution
The Buckingham canal is the largest source of (non-brackish) water draining into the Kovalam estuary. Built in the early 1800s, this canal running parallel to the coast, was used for navigation till 1954. Since then, the canal has gradually turned into a sewage channel for the city of Chennai.
With increasing urban development in the lands adjoining the canal, pollution in the canal has gone up. Suresh said that several factories, housing complexes and colleges dump untreated waste into the canal, which has contributed to declining fish yields in the aaru over the last 20-30 years. The fishermen have complained to the panchayat leaders and district administration several times, but no action has been taken. “They are not affected by it. They don’t care. Only we fishermen see the effects.”
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| Buckingham canal, just before it joins the Kovalam estuary. |
Unlike the polluters of Buckingham canal, some businesses are polluting the aaru in plain sight of fishing communities. Suresh pointed out to me a restaurant and a hospital, located at the head of a narrow channel of water, called chinna aaru, connecting the sea and the estuary on the northern side. “In the last couple of years, the restaurant and the hospital have been discharging untreated waste into the waters. As a result, there is almost no catch in the chinna aaru”, Suresh says.
The many fishing communities
Communities practicing various traditional fishing techniques have fished in the Kovalam estuary for generations. Everyone I spoke to said that the catch has been declining over the years, but the reservoir would be catastrophic. The area where the reservoir is proposed to be built is still a very good fishing ground for a few months starting with the monsoons.
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Crab fishers of Kundrakadu (June 2026) |
Along the chinna aaru, a couple of kilometres from the restaurant and the hospital, is a village called Kundrakaadu. There, Suresh and I meet a group of Dalit fishermen sitting on an upturned boat, chatting in the afternoon.
These fishermen catch crabs using kaccha, a basket shaped net tied to a cord which has a float at the other end. They put bait in the nets, drop the baskets into the water, and collect them after 20-30 minutes. Each boat drops around 80 nets, which on a good day, can yield about 5 kilos of crab.
None of them have gone fishing in the last few days. The water is dirty, full of algae, and stagnant, they said. They are waiting for some wind or rain, to bring in fresh water, which will bring in the crabs.
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| A kacha net used to catch crabs, held by Suresh. |
The Irulars are another marginalized indigenous community who fish in the aaru. Murugesan and Lakshmi are an Irular couple living in the outskirts of Kovalam in a hut made of asbestos sheets. They don’t have a patta for the land on which the hut stands. On the hot June afternoon when we met, they were sitting outside their hut, because the inside was too hot.
Whenever it rained, both of them would wade into the aaru, and catch prawns with their hands. The catch is small, just enough for them to eat. They can’t afford to eat prawns unless they caught it themselves.
In the dry months, Murugesan does daily wage work whenever he can find it. They did not know about the Mamallan reservoir, and were hoping to catch prawns when the rains came in mid-July.
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| Irulars Murugesan and Lakshmi outside their hut in the outskirts of Kovalam. (June 2026) |
The risk of flooding
In a different Irular settlement in Kannima Nagar near Nemmeli, I meet Selvam and his sister Mohana. This settlement came up after the tsunami, when Irulars displaced from elsewhere bought patta for a piece of land and built houses. At that time, twenty years ago, “we could catch prawns, crabs and madava meen all year round. We caught enough to sell,” said Selvam. But now he fished only for 3 months starting with the October monsoons, and the catch was just enough for consumption. He works as a daily wage construction worker outside of the fishing season.
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| Selvam and Mohana live in an Irula settlement on the boundary of the Kovalam estuary. |
Selvam and Mohana are worried by the Mamallan reservoir for a different reason – flooding. Their hamlet stands on the periphery of the aaru. In the monsoons, the aaru fills up with water and overflows into their hamlet and beyond. Every year their houses get flooded with knee-deep water, and they evacuate to a nearby school for some weeks. They expect the flooding to get much worse if the reservoir is built, since the flood waters will be obstructed from flowing into the sea.
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| The backyard of the Irula settlement. In the monsoons in October-November, this area is under water. |
Not just the Irula hamlet, all areas along the proposed reservoir face a higher risk of flooding. According to local fishermen and environmental activists, there are two threats posed by the construction of the reservoir: Water from the land, unable to reach the sea, will flood neighborhoods and houses. Secondly, in tidal surges during the monsoon, sea water can breach the bunds and flood the reservoir with salt water.
Pushed to the deep sea
Vennila, who is forty years old, belongs to a family of fishermen in Kovalam. She herself has a fishing net business. She sells nets of varying thickness and different weaves. Each fish requires a net of a specific thickness, she says. For example, prawns in the aaru and prawns in the sea are caught using nets of different thickness, because their sizes are different.
In my conversation with her, we took a step back from the immediate threat of the reservoir, and we discussed how fishing has transformed over the years in Kovalam.
Vennila said that the technology used for fishing has transformed. “Thirty years ago, fishermen in Kovalam used kattumarams (a traditional fishing boat made of tree trunks), but now they use engine-powered fiber boats which enable them to go much further out in the sea.”
“But on the other hand, pollution in the waters has forced fishermen to go deeper into the sea. Back then, the fish would come to the coast. Now we have to go into the sea and catch”, she said.
“Near the Kovalam coast, there is a big rock called paankkal, from whose crevices people caught crabs. Now those crevices just have plastic waste.”
“In the month of Thai (the Tamil month from mid-January to mid-February), the entire village would do a peria valai.” The peria valai, literally meaning big net, is a way of catching fish without a boat. About thirty-forty fishermen lay a large net by wading into the sea. There were sufficiently many fish close to the coast to yield a catch large enough to be shared between everybody.
Going deeper into the sea takes more resources and more time, and increases the fishermen’s exposure to risks such as storms. Vennila’s son, Natarajan goes twenty kilometers into the sea to fish. The trips are about 12 hours long, leaving at 1 am and returning at 1 pm. In contrast, Suresh’s fishing trips in the aaru were just 3 hours long.
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| Vennila and her son Natarajan in their house. |
The noose of capitalism
A recurring feature of capitalism is to restrict people’s access to commons and remove their means of independent subsistence, in order to make them reliant on wage labour. The state of Tamil Nadu has realized this capitalist goal through its inaction in regulating pollution of the wetlands, and its action of pushing for the Mamallan reservoir.
Inland fishing provides a source of income and nutrition that is accessible to marginalized fisherfolk, including fisherwomen. The Mamallan reservoir threatens to destroy these fishing commons.
The destruction feels senseless and cynical, because experts have proposed various cheaper and more sustainable alternatives to the Mamallan reservoir. Even the efficacy of the reservoir is in doubt because its barriers may be breached by seawater during tidal surges. But the government persists with this project blindly.
In Chennai, the struggles of fishing communities have always been a source of resistance against the appropriation of coastal land by private interests. If the Mamallan reservoir is constructed, the remainder of the wetland, with its hydrology thrown off balance, will turn into a wasteland with no possibility of fishing. This land may then end up in the control of real estate developers building luxury apartments with ‘expansive seaviews’.
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| A piece of an inland fishing boat. |
Epilogue
In the middle of August 2026, Suresh stopped fishing in the aaru. He started going to the sea for fishing, on a boat owned by a relative. “There is nothing in the aaru any more”, he said. The monsoon rains of July-August dredged up the dirt in the Buckingham canal, and the aaru is now filled with stagnant dirty water. The illegal mud block has prevented the dirt from being washed into the sea.
The Mamallan reservoir has already started wreaking destruction, even before it has received an environmental clearance. It is not too late to stop the project, reverse the destruction, work on regulating pollution and conserve the estuary with the participation of local fisherfolk.
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| The map of the area, in August 2026 |
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