Marginal reduction in polluted river stretches across India, most in Maharashtra: CPCB report

A polluted river stretch refers to two or more polluted locations on a river in a continuous sequence. Stretches where the biochemical oxygen demand (BOD) exceeds 3 milligrams/litre (mg/L) are identified as polluted stretches by CPCB. BOD in excess of prescribed levels indicates a higher pollution load, especially for the health of aquatic life.

There are five such priority categories, with Priority Class V, with BOD level of 3.1-6 mg/L, indicating the least pollution and in need of low intervention. BOD levels less than 3 mg/L are considered fit for bathing.

Stretches with BOD concentrations exceeding 30 mg/L are categorised as Priority I or the most polluted stretches. Out of 296 stretches identified as polluted, 37 were classified as the most polluted, or Priority I. This number has also seen a slight drop from 46 in the previous report.

These 37 stretches were identified across 14 states, with the highest number, five, in Tamil Nadu, Uttar Pradesh, and Uttarakhand; four in Gujarat, and three in Karnataka.

Among the most notable polluted river stretches included Yamuna’s stretch from Palla to Asgarpur in Delhi, Sabarmati in Ahmedabad, Chambal’s stretch from Nagda to Gandhisagar dam in Madhya Pradesh, and stretches of Tungabadhra and Sarabanga in Karnataka and Tamil Nadu, respectively.

River stretches with deterioration in water quality

Among the more prominent rivers where stretches were identified to have deteriorated in quality were Jhelum in Jammu and Kashmir; Ganga, Ramrekha and Sikrahna in Bihar; Hasdeo, Mahanadi in Chhattisgarh; Sal and Mapusa in Goa; Cauvery, Tungabhadra in Karnataka; Periyar in Kerala, and Amba and Savitri in Maharashtra. It also included stretches on Krishna in Telangana and Kosi in Uttarakhand.

In 2018, the National Green Tribunal (NGT) took suo motu cognisance of the CPCB’s river pollution assessment based on news reports and ordered states and the Centre to prepare action plans for rejuvenation.

According to the CPCB’s latest report, river rejuvenation committees were formed to develop action plans and reduce pollution. The CPCB has directed states to focus on river catchment and basin management, floodplain protection, and the treatment of sewage water.

Currently, water quality monitoring is carried out at 2,155 locations on 645 rivers under the National Water Quality Monitoring Programme, a nationwide initiative by the CPCB in collaboration with state pollution control boards.