The presence of salinity in river Periyar has further intensified following the failure of the north-east monsoon and it is posing a serious threat to the distribution of drinking water from Aluva Water Works to major parts of Ernakulam district of Kerala. The functioning of hundreds of industrial units and lift irrigation projects on the banks of the Periyar will be badly affected, if urgent steps are not taken to prevent the entry of salinity in the river.