Organic pollution and salinity intrusion have led to the decline of water quality in six river basins in the State, underlining the need for strict monitoring of water resources and initiating pollution-control measures to address public health hazards.

The finding has been published in a report on the Environmental Monitoring of Water Quality in the Uppala and Manjeswaram river basins in Kasaragod district, Ithikkara and Pallikkal river basins in Kollam, and the Ayiroor and Mamom river basins in Thiruvananthapuram published by the Centre for Water Resources Development and Management. Chief Minister Pinarayi Vijayan released the report at a function held here on Monday.

Poor quality

The study revealed poor quality in 75 per cent of the surface water samples in the Manjeswaram river basin while the rest were of marginal quality.

The majority of samples were found to be microbially contaminated and unsuitable even for irrigation.

In Uppala

The investigations carried out in the Uppala river basin found that 66 per cent of the surface water samples were of marginal quality and 34 per cent of poor quality.

As many as 66 per cent of the surface water samples in the Pallikal river basin were of marginal water quality while 17 per cent of the samples each were of fair water quality and good quality.

According to the report, 88 per cent of the surface water samples in the Ithikkara river basin had marginal water quality and 12 per cent showed poor quality. Organic pollution was reported to be high at several stations.

All the stations in the Ayiroor river basin showed marginal surface water quality while E-coli contamination was found to be highest during the monsoon.

The seasonal E-coli contamination of groundwater ranged from 30 to 62 per cent.

n the Mamom river basin, 78 per cent of the surface water samples showed marginal and 22 per cent poor water quality.