97 tanks to get Vrishabhavathi Valley's treated water

Buoyed by the improvement in the groundwater levels in Anekal, Chikkaballapur and surrounding places, authorities have decided to fill 97 tanks in Bengaluru North, Bengaluru South, Nelamangala and Tumakuru with secondary treated water from the Vrishabhavathi Valley.

The project, which is set to cost Rs 865 crore, will be executed by the Minor Irrigation Department and the Bangalore Water Supply and Sewerage Board (BWSSB). Under it, nearly 110 MLD of treated water will be pumped from the Nayandahalli sewage treatment plant (STP) to the lakes.

While water flows through natural canals into a few lakes, to reach the other lakes, the water will be pumped at two points — Veerananjipura Tank near Nelamangala and Honnudike near Tumakuru. A pipeline network of 84 km will be laid as a part of the project. The project also envisages supplying at least 15 MLD to Dobbspet Industrial Area.

Of the 97 tanks, 50 of them are located in Nelamangala taluk, 34 in Tumakuru, 10 tanks in Bengaluru North and three in Bengaluru South taluk.

According to Minor Irrigation Department officials, there is a “drastic” improvement in groundwater levels in Kolar and Chikkaballapur which are getting treated water from the Hebbal-Nagawara Valley (HN Valley).

“The groundwater levels had gone down up to 1,000 feet in Chikkaballapur, Kolar and the surrounding areas owing to overexploitation. However, it has now risen to at least 450 feet in many of these areas. We intend to bring about similar changes in the Bengaluru Rural and Tumakuru districts now,” said R Srinivasa Reddy, Executive Engineer, Minor Irrigation Department.

However, farmers around Kolar alleged that the quality concerns continue to haunt them. “For instance, at Lakshmi Sagara Lake, where the treated water first enters Kolar, frothing was observed, indicating the poor quality of water being supplied,” a farmer pointed out.

Professor T V Ramachandra from IISc said that contamination of groundwater could have serious implications. “While supplying water to these areas is a noble idea, pumping out contaminated water could have serious implications on health. If heavy metals enter the food chain, health issues are inevitable,” he said. He suggested that the authorities plan for the natural treatment of water.

“Tertiary treatment at this large scale could be a burden financially. However, they can construct a wetland and pump the water through. This could act as a natural cost-effective treatment,” he said.

Officials from the Minor Irrigation Department, however, asserted that the water flowing out into Chikkaballapur, Kolar and other areas is tested regularly and is found to be up to the standards.

In Phases II and III of the project, the authorities plan to fill up another 162 tanks across Nelamangala, Devanahalli and Doddaballapur from the
Mylasandra STP.