Has TN wasted ₹500 crore in building new water reservoir in Chennai?

The fifth reservoir gets water from excess inflow of the Krishna river into Kandaleru-Poondi (KP) canal

Chembarambakkam
Kannankottai-Thervoy Kandigai reservoir is supposed to address Chennai's drinking water demands. Representative Photo: PTI

When Home Minister Amit Shah visited Chennai, on November 21, he commissioned a new water reservoir, the Kannankottai-Thervoy Kandigai. Built at a cost of nearly ₹ 500 crore, the new reservoir is supposed to address the city’s drinking water demands. However, has the state government wasted money in building the new water reservoir?

As of 2020, the city’s annual water need is 15.66 (thousand million cubic feet (tmcft). It has four reservoirs — Poondi, Cholavaram, Red Hills, and Chembarambakkam. The total water storage capacity of these reservoirs is 11.257 tmcft. In order to meet the deficit, the state government planned to build new reservoirs. So the construction of a new reservoir was taken up in 2013 with a budget of ₹ 330 crore.

The Kannankottai-Thervoy Kandigai reservoir is the first such storage facility since Independence in the city. In 1876, the British had constructed Puzhal reservoir (also known as Red Hills reservoir). The last reservoir constructed in the city was Poondi reservoir in 1944, which was later named as Sathyamurthy Sagar, in memory of Sundara Sastri Sathyamurthy, the Mayor of Chennai who was instrumental in reservoir’s construction. It celebrated its 75th year in 2019.

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The fifth reservoir gets water from excess inflow of the Krishna river into Kandaleru-Poondi (KP) canal. A branch canal intercepting the KP canal has been built for 8.6 km. The water will be carried through this canal to the new reservoir. The new reservoir has a storage capacity of 1 tmcft, and needs to be filled twice a year.

“Though the government says it is the fifth reservoir, it does not add up as one. A new reservoir should be independent of the existing reservoirs. But this reservoir is built by diverting the water,” says A Veerappan, state secretary, Tamil Nadu Public Works Department Senior Engineers Association.

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The reservoir project has two components: the first takes the excess Krishna water through the canal and brings it to the new reservoir. For this purpose, 1,495 acres of land was acquired. The land acquisition process was the main reason why the project took seven years to complete. The government has spent ₹ 160 crore on land acquisition. The delay shot up the budget to ₹ 380 crore. “The branch canal is an open canal, so we will lose a considerable amount of water and there is a possibility that the water could get polluted”, alleges Veerappan.

“Instead of an open canal, if the government planned to channel water through roadside concrete tubes, the need for land acquisition could have been averted and the project could have been completed in over two years with a budget of ₹ 175.87 crores,” says Veerappan.

Why detouring?

Veerappan says it is the second part of the project that appears more problematic. “The water stored in Kannankottai-Thervoy Kandigai reservoir is taken through roadside concrete tubes for 17.5 kms and pumped again at KP canal. From there, the water runs for nearly 22 kms and joins in Poondi reservoir. For this part, the Chennai Metro Water Supply and Sewerage Board (CMWSSB) have spent ₹ 102.50 crore. So the total project cost is around ₹ 482.50 crore. This additional expenditure has not been added to the original cost of the project and the government continues to claim the reservoir was built with ₹ 380 crore,” says Veerappan.

Instead of making this detour, had the government allowed Poondi reservoir to attain its full capacity, we could have got an additional 3 tmcft water. However, the reservoir has mostly only 10-20 per cent water. In the existing 11.257 tmcft capacity, only 9 tmcft is allowed. That is achieved only during heavy rains, otherwise these reservoirs don’t go up beyond 5 tmcft, he said.

“The CMWSSB has predicted the water needs of the city at 15.66 tmcft. We already have 9 tmcft. Besides, we get water from Veeranam lake in Cuddalore district, desalination plants and agricultural wells in and around the city. From this we can get nearly 6 tmcft water. The CMWSSB expects that by 2030, the water demand will shoot up to 20 tmcft. If the four old reservoirs are filled twice a year and they are properly maintained, we can easily have 18 tmcft and for the remaining, we could have other sources. So constructing new reservoirs may not be required in the immediate future,” Veerappan said.

Rampant encroachment

N Meenakshisundaram, an engineer-turned-water activist, says the new reservoir construction should be welcomed. “In 1983, it was suggested that three reservoirs should be built in Ramancheri, Thirukkandalam, and Kannankottai-Thervoy Kandigai, all in Tiruvallur district. But in Ramancheri and Thirukkandalam, most land was allowed to be encroached on. That’s why the project didn’t take off. Considering the population, we need more such reservoirs,” he said.

The water in the reservoirs must be released only after it has attained its full reservoir level. But the government is not allowing the reservoirs to reach their full capacity because of the Chembarambakkam disaster in 2015, said K. Sivasubramaniyan, professor, Madras Institute of Development Studies.

“The areas around the reservoirs are encroached on. The bunds and sluices in the old reservoirs are not in a good condition. The government fears that if the reservoirs attain their full capacity, it could create another disaster similar to the one in 2015,” says Sivasubramaniyan.

The state is paying for the water received from Andhra Pradesh. It must give 12 tmcft per year. So far we have received 8 tmcft. In order to save excess water, we need a reservoir. Andhra is ready to share the full amount of water if it receives heavy rains. But to store that water, we didn’t have a reservoir and the excess water was wasted.

“This year we had a good rainfall, enabling us to store the water. Due to the new reservoir, the groundwater in the surrounding areas will be recharged. We should not worry about whether the water is carried straight or through detours,” says Sivasubramaniyan.

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