Krishna water flow props up Chennai reservoirs as monsoon deficit persists

Despite a weak southwest monsoon that has left Chennai's catchment areas dry, the city's reservoirs are receiving a steady inflow of Krishna water from Andhra Pradesh, helping to stabilise storage and maintain drinking water supply.

On Saturday, the Kandaleru Poondi canal, the entry point of Krishna water into Tamil Nadu, recorded an inflow of 464 cubic feet per second (cusecs). This inflow has prevented a rapid decline in reservoir levels at a time when no significant rainfall has been recorded in the region.

Chennai has historically depended on water from the Krishna river under an inter-state agreement to supplement its needs during dry periods. This year, Krishna water is the only source currently augmenting the storage in the city's reservoirs. The neighbouring districts of Tiruvallur and Kancheepuram have recorded a rainfall deficit of more than 25 per cent this season.

Officials from the Water Resources Department (WRD) said that the Andhra Pradesh government has increased the discharge of Krishna water to Chennai, despite low storage levels in its own reservoirs, including Kandaleru. During a visit by WRD and Chennai Metrowater officials last month, Andhra Pradesh had agreed to release about 400 cusecs of Krishna water.

“We had asked for an inflow of about 500 cusecs to shore up the dipping storage in our reservoirs. We usually receive such volumes only during the rainy season. But this time, water was released during a critical period even though Kandaleru reservoir has only 30 per cent of its total capacity,” an official said.

Since July 1, Chennai has received nearly 1,000 million cubic feet (mcft) of Krishna water, which has added to the overall storage. If about 500 cusecs of water is received daily, storage in Chennai's reservoirs could increase by nearly 1,300 mcft in about a month. This would be equivalent to one month's drinking water supply for the city.

Water received at Poondi reservoir is transferred to the Red Hills reservoir for the city's drinking water supply. Currently, the five major reservoirs have storage at about 44 per cent of their capacity. Water managers expect to avoid a water crisis this year with the available storage.

The WRD expects the release of Krishna water to be increased further in the coming days, which would provide additional relief as the monsoon season remains weak.