Bengaluru: Amidst the dark Covid-19 clouds, there may be a silver lining for the 10.5 million citizens of Chennai. The unprecedented water crisis that crippled Chennai last summer is unlikely to revisit the city in 2020. Thanks to a combination of good fortune and planning, the four lakes that feed the city are nearly 14 times fuller than last year. The average ground water level at 5.3 metres is 1. 5m higher than it was in March 2019.
“We are nowhere near the crisis we faced last year. The inflow into the lakes has been excellent and we’ve managed to significantly reduce the supply of freshwater to the industrial clusters by providing them recycled water,” said T Prabhushankar, executive director, Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB).
The crisis of 2019 was yet another reminder for Chennai that efficient use and prudent management of water resources were as important as big-ticket investments in desalination plants. The city already has two desalination plants with capacity of 210 million litres a day that service the northern suburbs. A third 150 million litre plant costing nearly Rs 1300 crore would be ready next year.
The city also took a raft of administrative measures. Two new tertiary treatment and reverse osmosis (TTRO) plants that recycle sewage into 90 million litres of potable water became operational by October 2019. The CMWSSB has now completely stopped supplying freshwater to the two big industrial clusters on the northern and western fringes of Chennai. Their requirements are met by the two recycling plants built at a cost of Rs 630 crore. The capacity of the plants would soon go up to 120 million litres a day. This has freed up domestic drinking water supplies and reduced the reliance on the already stressed ground water resources.
According to CMWSSB, higher domestic consumption given the emphasis on frequent handwashing and personal hygiene due to the lockdown may have evened out the lack of commercial demand for water. Commercial establishments account for close to 40-50 million litres of water a day. Even during the lockdown, the water utility has maintained the usual daily supply of 650 million litres. However, Prabhushankar said that given the storage levels, a further increase in demand could also be comfortably met.
In 2019, the four reservoirs around Chennai — Poondi, Red Hills, Chembarambakkam and Cholavaram— with a combined capacity of 11.3 billion cubic feet (BCft) had dried up by May leading to one of the worst water crises faced by the city. CMWSSB could barely supply half the city’s daily demand of 1 billion litres. The deep groundwater aquifers too dried up in the face of excessive extraction of water. Hotels, factories and large IT parks had to shut down for several days.
Although Chennai had made rainwater harvesting (RWH) mandatory in 2003 to get construction approvals and water connection, poor upkeep by citizens had rendered these structures non-functional. “Over the last nine months in collaboration with Greater Chennai Corporation we have inspected nearly 15 lakh households. We ordered nearly 500,000 households install new RWH systems. As a result, the ground waters levels we measure through 145 observation wells in the city have risen significantly,” said Prabhushankar. According to CMWSSB nearly 370 large community wells that had become defunct have been recharged as part of the groundwater renewal drive.
But experts said that these efforts may be inadequate. “The audit of RWH systems is not as easy as the government thinks. A lot of factors such as soil quality have to be accounted for. Those who carried out the surveys were simply not trained to do it. It was an exercise to divert public attention in the midst of a crisis. The public too continues to think of RWH as a tamasha ,” says Sekar Raghavan, a scientist known as Chennai’s ‘rain man’ who through his NGO Rain Centre has been a RWH evangelist for nearly three decades. He has been campaigning for an audit of Chennai’s RWH readiness by independent, specialist agencies. By Raghavan’s estimates, only 40 per cent of Chennai’s buildings have RWH systems that actually work.
The efforts of Chennai’s civic agencies notwithstanding, it is nature that has offered the biggest relief. The monsoon was only moderate in 2019. But the inter-river basin transfer of water to Chennai has ensured the city won’t go dry this year. Under the Telugu Ganga project initiated in the 1980s, Chennai’s four lifeline lakes are also fed by the waters of Krishna. The city also gets supplies from Veeranam, a giant lake 235 km to the south in Cuddalore district that depends on discharge from the Mettur dam on Cauvery river. Both Cauvery and Krishna river basins received such massive amounts of rain that storage levels in all dams on their course continue to remain healthy. Chennai’s lakes too, brimmed up with nearly 8 BCFt of Krishna water, the highest inflow in 25 years. Without the supply from the Krishna basin, Chennai’s lakes would have only had 1.4 BCFt of water even with normal rainfall. The combined storage of the reservoirs on April 24 was close to 6 BCFt compared to 415 MCFt at the same time last year.
“Thankfully, we don’t have to tackle two disasters at once this year. We can fully focus on dealing with Covid-19 instead of worrying about water supply,” said Prabhushankar.