Bhubaneswar: The Odisha State Pollution Control Board has expressed concern over water quality of 11 major river systems across the state with a recent study revealing water to be found unfit for human use at 90 places.

The board monitors water quality at 129 monitoring stations in 11 rivers - Mahanadi, Baitarani, Brahmani, Rushikulya, Nagavali, Subarnarekha, Kolab, Budhabalanga, Vamsadhara, Indravati and Bahuda.

The water quality at 36 monitoring stations in the Mahanadi river system was found to be polluted in 2017, while 29 monitoring stations in the Brahmani system were also found polluted. Similarly, 11 stations in the Baitarani system were found polluted.

"The water quality has degraded mostly due to discharge of domestic sewage without treatment. Besides direct discharge of waste from industries are also contributing to the river pollution. We have asked the concerned civic bodies to initiate action for treatment of domestic sewage before discharging it to the river system," said environmental scientist of the board B.N. Bhol.

While the Kathajodi (tributary of Mahanadi) and the Mahanadi are badly polluted downstream of Cuttack city, the Brahmani has been found to be carrying a large amount of municipal waste near Panposh and Rourkela. Kuakhai, also a tributary of Mahanadi is polluted along its stretch in Bhubaneswar.

The Daya river has also been found unsuitable for use at four places.

The housing and urban development department has written to the civic bodies for treatment of domestic used water.