Chittagong Correspondent High salinity in the down stream water of the River Karnaphuli, its major boughs and canals has reportedly been posing serious threat to usual output of the winter crop (Boro) at vast areas here in southern Chittagong apart from hindering safe drinking water supply in the port city. According to sources, at the Agricultural Information department more than 30 thousand hectors of croplands on both banks mainly in the down stream of the river and its branches have already started suffering from soil degradation because of high salinity. High concentration of salt in the river water is not only dangerous for the crop output, but repeated exposure to the toxicity may turn the croplands totally infertile for decades together even if not for ever. It is learnt that sea water surges the river's lower-mid and down stream with high-tides twice a day in the absence of the river's downward rush because of the draught-like situation at the upper stream. Some of the farmers in southern Chittagong (Anwara, Patiya, Boalkhali, Bakalia and Chandanaish) admitted that they had already suffered unusually low production or total crop-loss after using toxic river water for irrigation defying the salinity factor. On the other hand, Chittagong Water and Sewer Authority (WASA) has been facing enormous trouble in supplying safe drinking water to its consumers in the urban areas as it takes feed from the river Halda, main bough of the Karnaphuli, for the Mohora Water Treatment Plant. The WASA officials said that the salinity neutralisation units of the water treatment plant had become grossly inefficient against the high concentration of sodium chloride in the river water taken for treatment resulting in drastic fall of water supply. The regional office of the Soil Research Development Institute (SRDI) here in the port city, after receiving complaints from the farmers, undertook an initial survey to determine the concentration of sodium chloride in the Karnaphuli's water. It procured water samples from different points of the River Karnaphuli, its boughs and canals in early January this year and carried out laboratory analysis of the samples. The laboratory analysis detected extremely high concentration of Sodium Chloride (common salt) including other form of salts like magnesium chloride, magnesium sulphate, calcium sulphate and potassium chloride in the samples. According to the latest salinity survey the concentration of salt at the samples procured from Anwara, Patiya, Boalkhali and Kalurghat fluctuated between 3.1 and 8.6 ds/m (Deci-Simons in each meter) against the permissible level of .75 ds/m. "The samples are as like as normal sea water and totally unfit for irrigation and substituting the purposes of sweet water," an agro-chemist commented and suggested avoiding repeated exposure of the crop land to the toxic sea water. According to the rainfall records in the region and the upper stream of the River Karnaphuli, there had been insignificant rainfall in the lean season (November to March) in 2007 and 2008. Meteorologists also predict relatively poor rainfall during the current lean season (November to March) further sliming the chance of washing out the sea water from the river. "The croplands having history of flooding by sea water in the recent past will rather turn totally infertile for crop whatsoever until total washing of the soil's top layer by heavy and continuous shower," regional head of the SRDI Mir Shahabuddin feared. He said that, research had been in progress at home and abroad for developing variety of rice and alternative crops especially tolerant to moderate salinity.