Bengaluru: Quality of river water in Karnataka has failed to improve despite efforts by authorities to control pollution. The state has not been able to construct essential sewage treatment plants and other infrastructure to arrest the growing contamination.
According to a Karnataka State Pollution Control Board (KSPCB) report, over 708 km of seven major rivers and its tributaries have levels of contamination ranging from Class B, or waters used for organised outdoor bathing, to D, or water to maintain aquatic life.
Arkavathi, Tungabhadra and some sections of the Cauvery are classified as Class D. Only three rivers--Kali, Kumaradhara and Netravati--are classified under Class B, the KSPCB report showed.
The report of poor river water quality add to the troubles of calamity-prone Karnataka that has been hit by droughts and floods in the recent years. Rapid and unplanned urbanisation in Bengaluru has also led to encroachments of lakes and over exploitation of underground water tables that have pushed the city of over 10 million to the brink of crisis. Many of the city's housing complexes are now forced to buy water.
Water quality with Class A can be used for drinking without conventional treatment but after disinfection, while Class C requires conventional treatment followed by disinfection. Class E water is fit for irrigation, industrial cooling and controlled waste disposal.
Of the 98 water quality monitoring stations, at least 42 have reported serious, if not dangerous, levels of pollution, officials said.
"Only when it rains, the quality of river water improves," said a senior official at the pollution control board, requesting not to be named.
This indicates that human intervention that includes proposed construction of sewage treatment infrastructure and regulation of discharge directly into rivers is missing.
In some cases, fecal coliform (FC) bacteria has more than doubled, according to the state government data.
In one stretch of Arkavathi, FC was up from 7,000 in MPN (most probable number) per 100 ml in November to 14,000 MPN/100 ml in December. In aquatic environments, FC indicates the level of human fecal material or other animals that contaminates the water.
According to its action plan, the state pollution control board has set a two-year target from April 2019 to March 2021 to improve the quality of river water in these specified stretches. Of the total ₹1,427.20 crores, ₹827.93 crore has been approved and the work is underway, and ₹599.27 crore is proposed to complete projects under the action plan.
The report also showed that over 700 million litres per day (MLD) of sewage is being generated on these stretches but the capacity to treat this waste is still being built or nonexistent.
It is KSPCB’s primary job to ensure that industries and municipalities comply in discharging effluents and sewage generated along water bodies, said TV Ramachandra from the Centre for Ecological Sciences. Ramachandra specialises in energy, wetlands, soil and water pollution.