The upstream and downstream regions of Pathalam bund in Periyar should be de-silted and bio-remediation measures undertaken for saving the river system, suggested experts. They have also called for forming a Periyar River Monitoring Authority for the overall development and sustainability of Periyar river system. The suggestions came from a group of researchers of the Cochin University of Science and Technology who looked into the incidents of the fish kill in the river system. The study was done for Kerala State Pollution Control Board by a team led by S. Bijoy Nandan, Associate Professor of the Department of Marine Biology, Microbiology Biochemistry of the University. The team had P.S. Suson, M.K. Vishnu Sagar and P.V. Vineetha as its members. The temporary earthen bunds constructed in Periyar at Pathalam and Purapallikavu for checking saline water intrusion into the river system have been obstructing the normal flow of the river from the upstream parts to the lower stretches. The stagnant water in the Pathalam region with chemical pollutants from the nearby industries has been affecting the water quality and existence of biological life. More than 200 chemical industrial units are located in the region. The poor water quality in the downstream stretches of the Periyar had led to 10 incidents of fish kill since 1976. A major fish kill was reported on April 5 last year leading to widespread protests. The State government had asked the Board to probe the issue and to make suggestions for saving the river system, the report said. Many areas of the river adjacent to the upstream of Pathalam bund and in the downstream regions have become dead with high organic load. The improper closing and opening of Pathalam and Purapallikavu bunds during tides and lack of proper flushing has led to the accumulation of polluted water in the upstream areas for years. This has led to major fish kill in the river system, the report said. The synchronised opening and closing of the bunds in coordination with the Board, Irrigation Department and local bodies and a direction to industrial units to release the treated effluents through pipes above ground to a common treatment facility have been suggested. The common treatment facility of the treated effluent and other wastes generated from other sources should be managed by local self-governments and other governmental agencies. The toxic chemicals in the treated effluents released by the industries could also be responsible for fish kill, the researchers concluded. An integrated waste treatment system in upstream region of the Periyar for treating the household wastes from Aluva and Kalamassery regions should also be introduced, it was suggested.