In the past, the city of Bengaluru in Karnataka relied on the Arkavati river as a key source of water supply. Water from the river was stored at the Hessarghatta and Thippagondanahalli reservoirs and was further carried to the city. However, owing to the constant expansion of the city limits as well as the increased water requirements over time, other sources of water supply such as the Cauvery river were identified. The city’s water utility, the Bangalore Water Supply and Sewerage Board (BWSSB) therefore implemented the Cauvery Water Supply Scheme (CWSS), in various stages, to meet the growing requirements. Over the years, the Cauvery river has emerged as the main source of water supply for the city.
Cauvery Water Supply Scheme
BWSSB initiated Stage I of the CWSS way back in 1974. Subsequently, Stages II and III of the scheme were launched in 1982 and 1993 respectively. Under these three stages, BWSSB installed a total water supply capacity of 540 million litres per day (mld) for Bengaluru.
However, sourcing water from the Cauvery river has always been a cause for dispute among states situated within the river basin. In a bid to mitigate such issues, the central government set up the Cauvery Water Disputes Tribunal in June 1990. After over 16 years of dispute hearings, the tribunal released its final order for water sharing between the states in February 2007.
The tribunal determined that in total 740 thousand million cubic feet (tmcft) of water from the Cauvery river could be sourced by the states for potable use. According to the official order, this quantum of water was distributed among Karnataka (270 tmcft), Tamil Nadu (419 tmcft), Kerala (30 tmcft) and Puducherry (7 tmcft). In addition, the tribunal reserved 14 tmcft water for environmental purposes.
Of Karnataka’s total water allocation, about 19 tmcft was allocated for meeting Bengaluru’s water requirements. Subsequently, BWSSB commissioned Stage IV of the CWSS in two phases. While Phase I of the project was commissioned in 2002, Phase II was commissioned in 2012. About 770 mld of combined capacity was developed under Stage IV. Together, under the four stages of the CWSS, about 1,310 mld of capacity has been installed to cater to a population of about 8.5 million. BWSSB provides this water to a 570 square km area within Bruhat Bengaluru Mahanagara Palike (BBMP) limits.
However, with the commissioning of the CWSS, Stage IV, Phase II, Bengaluru exhausted the 19 tmcft water allocated to the city by the Karnataka government. At the same time, 110 villages were added to BBMP limits, leading to a further increase in the city’s water requirements. To meet the water demand of the newly added areas, an additional allocation of 10 tmcft (775 mld) of Cauvery water was made by the state government. To tap this allocation, BWSSB announced CWSS, Stage V, in 2010.
CWSS, Stage V
Under Stage V of the scheme, the board has proposed the development of 775 mld capacity in two phases. While Phase I will draw 500 mld (6.45 tmcft) from the river, Phase II is expected to draw 275 mld (3.55 tmcft).
The project aims at supplying water to the 110 villages located in five zones under BBMP – Byatarayanapura, Mahadevapura, Bommanahalli, Raja Rajeshwari Nagar and Dasarahalli. The scope of work involves laying a water pipeline network spanning a length of 2,817 km and the construction of a new 300 mld water treatment plant (WTP) at Thorekadanahalli (T.K. Halli).
The project (Stage V) will be implemented at an investment of Rs 32 billion. Financing will be through a combination of government allocation and a long-term loan from the Japan International Cooperation Agency (JICA). In this regard, BWSSB has sent a loan proposal to JICA for the project.
Progress under Stage V
While the state government had approved Stage V of the CWSS in 2015, the proposal for funding the project had been rejected by JICA owing to the lack of clarity about the source of water supply in the detailed project report. Subsequently, BWSSB assigned Bengaluru-based NMT Consultant to study the availability of water and assess the condition of the infrastructure required under the project. The company is expected to submit a final report to BWSSB by February 2017. Once the board works out these issues, JICA is expected to consider the project for funding once again.
Meanwhile, in 2015, BWSSB commenced construction work on the WTP, which is expected to be completed by November 2017. However, other components of the project are still in the preliminary stages of implementation. Currently, the land acquisition for laying pipelines is under way. BWSSB expects the entire project to be completed by end-2019.
The way forward
In spite of BWSSB’s relentless efforts to enhance water supply to Bengaluru, there has been a consistent shortfall in the water supplied to the region. The shortfall arises from the limited quantum of water that can be sourced from the Cauvery river for the city. Such inadequate supplies have led to rising disputes between the beneficiary states regarding river water sharing. The most recent dispute was witnessed in the form of water riots in Bengaluru and Chennai in September-October 2016.
What is even more worrying is the fact that as Bengaluru’s population grows further, this water supply deficit is only set to worsen in the years to come. According to BWSSB estimates, while Bengaluru’s water demand will rise to 27.1 tmcft by 2021, BWSSB will be able to supply about 26.7 tmcft. Therefore, about 0.4 tmcft of the requirements will be unmet. By 2031, the demand-supply gap will increase further to 10.69 tmcft.
Certainly, Bengaluru cannot rely only on the Cauvery river or its erstwhile water resources such as the Arkavati river. Presently, the Cauvery river supplies water to four states in the country and there is a limit to the water that can be drawn from the river. Further, with the increasing dependence on borewells, groundwater levels in the outer limits of BBMP’s area have also witnessed a significant drop.
Thus, an urgent need has been felt to develop other reliable water sources and in this regard several initiatives are already under way. For instance, the state government is planning to undertake rejuvenation works of the Hessarghatta lake near the city. The government plans to divert water from the Yettinahole river diversion project to the lake. Once revived, it is expected to hold about 1.1 tmcft of water. Moreover, BWSSB is also considering the Barapole river as another potential surface water source for the city.
That said, at present Bengaluru is reeling under a severe water crisis, which is only expected to worsen in the months to come. Considering the increasing demand for water, there is an urgent need to develop alternative sources of water supply. At the same time, BWSSB will have to take appropriate steps such as rainwater harvesting, reusing wastewater and reducing non-revenue water and leakages to ensure judicious use of the present freshwater resources.